models: Extract zerver.models.streams.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

tools/semgrep-py.yml

@@ -49,7 +49,7 @@ rules:
       - pattern-not: from zerver.lib.utils import generate_api_key
       - pattern-not: from zerver.models.linkifiers import filter_pattern_validator
       - pattern-not: from zerver.models.linkifiers import url_template_validator
-      - pattern-not: from zerver.models import generate_email_token_for_stream
+      - pattern-not: from zerver.models.streams import generate_email_token_for_stream
       - pattern-not: from zerver.models.realms import generate_realm_uuid_owner_secret
       - pattern-either:
           - pattern: from zerver import $X

web/src/settings_config.ts

@@ -1006,7 +1006,7 @@ export const stream_privacy_policy_values = {
 
 export const stream_post_policy_values = {
     // These strings should match the strings in the
-    // Stream.POST_POLICIES object in zerver/models/__init__.py.
+    // Stream.POST_POLICIES object in zerver/models/streams.py.
     everyone: {
         code: StreamPostPolicy.EVERYONE,
         description: $t({defaultMessage: "Everyone"}),

zerver/actions/default_streams.py

@@ -8,13 +8,8 @@ from zerver.lib.default_streams import (
     get_default_streams_for_realm_as_dicts,
 )
 from zerver.lib.exceptions import JsonableError
-from zerver.models import (
+from zerver.models import DefaultStream, DefaultStreamGroup, Realm, Stream
-    DefaultStream,
+from zerver.models.streams import get_default_stream_groups
-    DefaultStreamGroup,
-    Realm,
-    Stream,
-    get_default_stream_groups,
-)
 from zerver.models.users import active_non_guest_user_ids
 from zerver.tornado.django_api import send_event_on_commit
 

zerver/actions/message_edit.py

@@ -76,8 +76,8 @@ from zerver.models import (
     UserMessage,
     UserProfile,
     UserTopic,
-    get_stream_by_id_in_realm,
 )
+from zerver.models.streams import get_stream_by_id_in_realm
 from zerver.models.users import get_system_bot
 from zerver.tornado.django_api import send_event
 

zerver/actions/message_send.py

@@ -103,12 +103,11 @@ from zerver.models import (
     UserProfile,
     UserTopic,
     get_client,
-    get_stream,
-    get_stream_by_id_in_realm,
     query_for_ids,
 )
 from zerver.models.groups import SystemGroups
 from zerver.models.recipients import get_huddle_user_ids
+from zerver.models.streams import get_stream, get_stream_by_id_in_realm
 from zerver.models.users import get_system_bot, get_user_by_delivery_email, is_cross_realm_bot_email
 from zerver.tornado.django_api import send_event
 

zerver/data_import/rocketchat.py

@@ -182,7 +182,7 @@ def convert_channel_data(
         # should be allowed to post in the converted Zulip stream.
         # For more details: https://zulip.com/help/stream-sending-policy
         #
-        # See `Stream` model in `zerver/models/__init__.py` to know about what each
+        # See `Stream` model in `zerver/models/streams.py` to know about what each
         # number represent.
         stream_post_policy = 4 if channel_dict.get("ro", False) else 1
 

zerver/lib/cache.py

@@ -639,7 +639,7 @@ def realm_text_description_cache_key(realm: "Realm") -> str:
     return f"realm_text_description:{realm.string_id}"
 
 
-# Called by models/__init__.py to flush the stream cache whenever we save a stream
+# Called by models/streams.py to flush the stream cache whenever we save a stream
 # object.
 def flush_stream(
     *,

zerver/lib/digest.py

@@ -29,8 +29,8 @@ from zerver.models import (
     Subscription,
     UserActivityInterval,
     UserProfile,
-    get_active_streams,
 )
+from zerver.models.streams import get_active_streams
 
 logger = logging.getLogger(__name__)
 log_to_file(logger, settings.DIGEST_LOG_PATH)

zerver/lib/email_mirror.py

@@ -37,8 +37,8 @@ from zerver.models import (
     Stream,
     UserProfile,
     get_client,
-    get_stream_by_id_in_realm,
 )
+from zerver.models.streams import get_stream_by_id_in_realm
 from zerver.models.users import get_system_bot, get_user_profile_by_id
 from zproject.backends import is_user_active
 

zerver/lib/events.py

@@ -80,13 +80,13 @@ from zerver.models import (
     UserStatus,
     UserTopic,
     custom_profile_fields_for_realm,
-    get_default_stream_groups,
 )
 from zerver.models.constants import MAX_TOPIC_NAME_LENGTH
 from zerver.models.linkifiers import linkifiers_for_realm
 from zerver.models.realm_emoji import get_all_custom_emoji_for_realm
 from zerver.models.realm_playgrounds import get_realm_playgrounds
 from zerver.models.realms import get_realm_domains
+from zerver.models.streams import get_default_stream_groups
 from zerver.tornado.django_api import get_user_events, request_event_queue
 from zproject.backends import email_auth_enabled, password_auth_enabled
 

zerver/lib/mention.py

@@ -7,7 +7,8 @@ from django.conf import settings
 from django.db.models import Q
 
 from zerver.lib.users import get_inaccessible_user_ids
-from zerver.models import UserGroup, UserProfile, get_linkable_streams
+from zerver.models import UserGroup, UserProfile
+from zerver.models.streams import get_linkable_streams
 
 BEFORE_MENTION_ALLOWED_REGEX = r"(?<![^\s\'\"\(\{\[\/<])"
 

zerver/lib/narrow.py

@@ -75,15 +75,8 @@ from zerver.lib.validator import (
     check_string_or_int,
     check_string_or_int_list,
 )
-from zerver.models import (
+from zerver.models import Realm, Recipient, Stream, Subscription, UserMessage, UserProfile
-    Realm,
+from zerver.models.streams import get_active_streams
-    Recipient,
-    Stream,
-    Subscription,
-    UserMessage,
-    UserProfile,
-    get_active_streams,
-)
 from zerver.models.users import (
     get_user_by_id_in_realm_including_cross_realm,
     get_user_including_cross_realm,

zerver/lib/streams.py

@@ -30,12 +30,14 @@ from zerver.models import (
     Subscription,
     UserGroup,
     UserProfile,
+)
+from zerver.models.groups import SystemGroups
+from zerver.models.streams import (
     bulk_get_streams,
     get_realm_stream,
     get_stream,
     get_stream_by_id_in_realm,
 )
-from zerver.models.groups import SystemGroups
 from zerver.models.users import active_non_guest_user_ids, active_user_ids, is_cross_realm_bot_email
 from zerver.tornado.django_api import send_event
 

zerver/lib/subscription_info.py

@@ -25,7 +25,8 @@ from zerver.lib.types import (
     SubscriptionInfo,
     SubscriptionStreamDict,
 )
-from zerver.models import Realm, Stream, Subscription, UserProfile, get_active_streams
+from zerver.models import Realm, Stream, Subscription, UserProfile
+from zerver.models.streams import get_active_streams
 
 
 def get_web_public_subs(realm: Realm) -> SubscriptionInfo:

zerver/lib/test_classes.py

@@ -107,11 +107,10 @@ from zerver.models import (
     UserMessage,
     UserProfile,
     UserStatus,
-    get_realm_stream,
-    get_stream,
 )
 from zerver.models.groups import SystemGroups
 from zerver.models.realms import clear_supported_auth_backends_cache, get_realm
+from zerver.models.streams import get_realm_stream, get_stream
 from zerver.models.users import get_system_bot, get_user, get_user_by_delivery_email
 from zerver.openapi.openapi import validate_against_openapi_schema, validate_request
 from zerver.tornado.event_queue import clear_client_event_queues_for_testing

zerver/lib/test_helpers.py

@@ -60,9 +60,9 @@ from zerver.models import (
     UserMessage,
     UserProfile,
     get_client,
-    get_stream,
 )
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 from zerver.tornado.handlers import AsyncDjangoHandler, allocate_handler_id
 from zilencer.models import RemoteZulipServer
 from zproject.backends import ExternalAuthDataDict, ExternalAuthResult

zerver/lib/user_topics.py

@@ -12,7 +12,8 @@ from sqlalchemy.types import Integer
 from zerver.lib.timestamp import datetime_to_timestamp
 from zerver.lib.topic import topic_match_sa
 from zerver.lib.types import UserTopicDict
-from zerver.models import UserProfile, UserTopic, get_stream
+from zerver.models import UserProfile, UserTopic
+from zerver.models.streams import get_stream
 
 
 def get_user_topics(

zerver/management/commands/merge_streams.py

@@ -5,7 +5,7 @@ from typing_extensions import override
 
 from zerver.actions.streams import merge_streams
 from zerver.lib.management import ZulipBaseCommand
-from zerver.models import get_stream
+from zerver.models.streams import get_stream
 
 
 class Command(ZulipBaseCommand):

zerver/management/commands/remove_users_from_stream.py

@@ -5,7 +5,7 @@ from typing_extensions import override
 
 from zerver.actions.streams import bulk_remove_subscriptions
 from zerver.lib.management import ZulipBaseCommand
-from zerver.models import get_stream
+from zerver.models.streams import get_stream
 
 
 class Command(ZulipBaseCommand):

zerver/management/commands/send_to_email_mirror.py

@@ -13,8 +13,9 @@ from typing_extensions import override
 from zerver.lib.email_mirror import mirror_email_message
 from zerver.lib.email_mirror_helpers import encode_email_address
 from zerver.lib.management import ZulipBaseCommand
-from zerver.models import Realm, get_stream
+from zerver.models import Realm
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 
 # This command loads an email from a specified file and sends it
 # to the email mirror. Simple emails can be passed in a JSON file,

zerver/migrations/0001_initial.py

@@ -12,7 +12,7 @@ from django.db.backends.base.schema import BaseDatabaseSchemaEditor
 from django.db.migrations.state import StateApps
 from django.db.models.functions import Upper
 
-from zerver.models import generate_email_token_for_stream
+from zerver.models.streams import generate_email_token_for_stream
 
 
 def migrate_existing_attachment_data(

zerver/migrations/0212_make_stream_email_token_unique.py

@@ -2,7 +2,7 @@
 
 from django.db import migrations, models
 
-from zerver.models import generate_email_token_for_stream
+from zerver.models.streams import generate_email_token_for_stream
 
 
 class Migration(migrations.Migration):

zerver/models/__init__.py

@@ -2,10 +2,9 @@
 # mypy: disable-error-code="explicit-override"
 
 import hashlib
-import secrets
 import time
 from datetime import datetime, timedelta, timezone
-from typing import Any, Callable, Dict, List, Optional, Set, Tuple, TypedDict, TypeVar, Union
+from typing import Any, Callable, Dict, List, Optional, Tuple, TypedDict, TypeVar, Union
 
 import orjson
 from bitfield import BitField
@@ -34,7 +33,6 @@ from zerver.lib.cache import (
     cache_with_key,
     flush_message,
     flush_muting_users_cache,
-    flush_stream,
     flush_submessage,
     flush_used_upload_space_cache,
     realm_alert_words_automaton_cache_key,
@@ -44,11 +42,9 @@ from zerver.lib.display_recipient import get_recipient_ids
 from zerver.lib.exceptions import RateLimitedError
 from zerver.lib.timestamp import datetime_to_timestamp
 from zerver.lib.types import (
-    DefaultStreamDict,
     ExtendedFieldElement,
     ExtendedValidator,
     FieldElement,
-    GroupPermissionSetting,
     ProfileDataElementBase,
     ProfileDataElementValue,
     RealmUserValidator,
@@ -66,7 +62,6 @@ from zerver.lib.validator import (
 )
 from zerver.models.constants import MAX_TOPIC_NAME_LENGTH
 from zerver.models.groups import GroupGroupMembership as GroupGroupMembership
-from zerver.models.groups import SystemGroups
 from zerver.models.groups import UserGroup as UserGroup
 from zerver.models.groups import UserGroupMembership as UserGroupMembership
 from zerver.models.linkifiers import RealmFilter as RealmFilter
@@ -84,6 +79,10 @@ from zerver.models.realms import RealmAuthenticationMethod as RealmAuthenticatio
 from zerver.models.realms import RealmDomain as RealmDomain
 from zerver.models.recipients import Huddle as Huddle
 from zerver.models.recipients import Recipient as Recipient
+from zerver.models.streams import DefaultStream as DefaultStream
+from zerver.models.streams import DefaultStreamGroup as DefaultStreamGroup
+from zerver.models.streams import Stream as Stream
+from zerver.models.streams import Subscription as Subscription
 from zerver.models.users import RealmUserDefault as RealmUserDefault
 from zerver.models.users import UserBaseSettings as UserBaseSettings
 from zerver.models.users import UserProfile as UserProfile
@@ -143,202 +142,6 @@ def query_for_ids(
     return query
 
 
-def generate_email_token_for_stream() -> str:
-    return secrets.token_hex(16)
-
-
-class Stream(models.Model):
-    MAX_NAME_LENGTH = 60
-    MAX_DESCRIPTION_LENGTH = 1024
-
-    name = models.CharField(max_length=MAX_NAME_LENGTH, db_index=True)
-    realm = models.ForeignKey(Realm, db_index=True, on_delete=CASCADE)
-    date_created = models.DateTimeField(default=timezone_now)
-    deactivated = models.BooleanField(default=False)
-    description = models.CharField(max_length=MAX_DESCRIPTION_LENGTH, default="")
-    rendered_description = models.TextField(default="")
-
-    # Foreign key to the Recipient object for STREAM type messages to this stream.
-    recipient = models.ForeignKey(Recipient, null=True, on_delete=models.SET_NULL)
-
-    # Various permission policy configurations
-    PERMISSION_POLICIES: Dict[str, Dict[str, Any]] = {
-        "web_public": {
-            "invite_only": False,
-            "history_public_to_subscribers": True,
-            "is_web_public": True,
-            "policy_name": gettext_lazy("Web-public"),
-        },
-        "public": {
-            "invite_only": False,
-            "history_public_to_subscribers": True,
-            "is_web_public": False,
-            "policy_name": gettext_lazy("Public"),
-        },
-        "private_shared_history": {
-            "invite_only": True,
-            "history_public_to_subscribers": True,
-            "is_web_public": False,
-            "policy_name": gettext_lazy("Private, shared history"),
-        },
-        "private_protected_history": {
-            "invite_only": True,
-            "history_public_to_subscribers": False,
-            "is_web_public": False,
-            "policy_name": gettext_lazy("Private, protected history"),
-        },
-        # Public streams with protected history are currently only
-        # available in Zephyr realms
-        "public_protected_history": {
-            "invite_only": False,
-            "history_public_to_subscribers": False,
-            "is_web_public": False,
-            "policy_name": gettext_lazy("Public, protected history"),
-        },
-    }
-    invite_only = models.BooleanField(default=False)
-    history_public_to_subscribers = models.BooleanField(default=True)
-
-    # Whether this stream's content should be published by the web-public archive features
-    is_web_public = models.BooleanField(default=False)
-
-    STREAM_POST_POLICY_EVERYONE = 1
-    STREAM_POST_POLICY_ADMINS = 2
-    STREAM_POST_POLICY_RESTRICT_NEW_MEMBERS = 3
-    STREAM_POST_POLICY_MODERATORS = 4
-    # TODO: Implement policy to restrict posting to a user group or admins.
-
-    # Who in the organization has permission to send messages to this stream.
-    stream_post_policy = models.PositiveSmallIntegerField(default=STREAM_POST_POLICY_EVERYONE)
-    POST_POLICIES: Dict[int, StrPromise] = {
-        # These strings should match the strings in the
-        # stream_post_policy_values object in stream_data.js.
-        STREAM_POST_POLICY_EVERYONE: gettext_lazy("All stream members can post"),
-        STREAM_POST_POLICY_ADMINS: gettext_lazy("Only organization administrators can post"),
-        STREAM_POST_POLICY_MODERATORS: gettext_lazy(
-            "Only organization administrators and moderators can post"
-        ),
-        STREAM_POST_POLICY_RESTRICT_NEW_MEMBERS: gettext_lazy(
-            "Only organization full members can post"
-        ),
-    }
-    STREAM_POST_POLICY_TYPES = list(POST_POLICIES.keys())
-
-    # The unique thing about Zephyr public streams is that we never list their
-    # users.  We may try to generalize this concept later, but for now
-    # we just use a concrete field.  (Zephyr public streams aren't exactly like
-    # invite-only streams--while both are private in terms of listing users,
-    # for Zephyr we don't even list users to stream members, yet membership
-    # is more public in the sense that you don't need a Zulip invite to join.
-    # This field is populated directly from UserProfile.is_zephyr_mirror_realm,
-    # and the reason for denormalizing field is performance.
-    is_in_zephyr_realm = models.BooleanField(default=False)
-
-    # Used by the e-mail forwarder. The e-mail RFC specifies a maximum
-    # e-mail length of 254, and our max stream length is 30, so we
-    # have plenty of room for the token.
-    email_token = models.CharField(
-        max_length=32,
-        default=generate_email_token_for_stream,
-        unique=True,
-    )
-
-    # For old messages being automatically deleted.
-    # Value NULL means "use retention policy of the realm".
-    # Value -1 means "disable retention policy for this stream unconditionally".
-    # Non-negative values have the natural meaning of "archive messages older than <value> days".
-    MESSAGE_RETENTION_SPECIAL_VALUES_MAP = {
-        "unlimited": -1,
-        "realm_default": None,
-    }
-    message_retention_days = models.IntegerField(null=True, default=None)
-
-    # on_delete field here is set to RESTRICT because we don't want to allow
-    # deleting a user group in case it is referenced by this setting.
-    # We are not using PROTECT since we want to allow deletion of user groups
-    # when realm itself is deleted.
-    can_remove_subscribers_group = models.ForeignKey(UserGroup, on_delete=models.RESTRICT)
-
-    # The very first message ID in the stream.  Used to help clients
-    # determine whether they might need to display "more topics" for a
-    # stream based on what messages they have cached.
-    first_message_id = models.IntegerField(null=True, db_index=True)
-
-    stream_permission_group_settings = {
-        "can_remove_subscribers_group": GroupPermissionSetting(
-            require_system_group=True,
-            allow_internet_group=False,
-            allow_owners_group=False,
-            allow_nobody_group=False,
-            allow_everyone_group=True,
-            default_group_name=SystemGroups.ADMINISTRATORS,
-            id_field_name="can_remove_subscribers_group_id",
-        ),
-    }
-
-    class Meta:
-        indexes = [
-            models.Index(Upper("name"), name="upper_stream_name_idx"),
-        ]
-
-    @override
-    def __str__(self) -> str:
-        return self.name
-
-    def is_public(self) -> bool:
-        # All streams are private in Zephyr mirroring realms.
-        return not self.invite_only and not self.is_in_zephyr_realm
-
-    def is_history_realm_public(self) -> bool:
-        return self.is_public()
-
-    def is_history_public_to_subscribers(self) -> bool:
-        return self.history_public_to_subscribers
-
-    # Stream fields included whenever a Stream object is provided to
-    # Zulip clients via the API.  A few details worth noting:
-    # * "id" is represented as "stream_id" in most API interfaces.
-    # * "email_token" is not realm-public and thus is not included here.
-    # * is_in_zephyr_realm is a backend-only optimization.
-    # * "deactivated" streams are filtered from the API entirely.
-    # * "realm" and "recipient" are not exposed to clients via the API.
-    API_FIELDS = [
-        "date_created",
-        "description",
-        "first_message_id",
-        "history_public_to_subscribers",
-        "id",
-        "invite_only",
-        "is_web_public",
-        "message_retention_days",
-        "name",
-        "rendered_description",
-        "stream_post_policy",
-        "can_remove_subscribers_group_id",
-    ]
-
-    def to_dict(self) -> DefaultStreamDict:
-        return DefaultStreamDict(
-            can_remove_subscribers_group=self.can_remove_subscribers_group_id,
-            date_created=datetime_to_timestamp(self.date_created),
-            description=self.description,
-            first_message_id=self.first_message_id,
-            history_public_to_subscribers=self.history_public_to_subscribers,
-            invite_only=self.invite_only,
-            is_web_public=self.is_web_public,
-            message_retention_days=self.message_retention_days,
-            name=self.name,
-            rendered_description=self.rendered_description,
-            stream_id=self.id,
-            stream_post_policy=self.stream_post_policy,
-            is_announcement_only=self.stream_post_policy == Stream.STREAM_POST_POLICY_ADMINS,
-        )
-
-
-post_save.connect(flush_stream, sender=Stream)
-post_delete.connect(flush_stream, sender=Stream)
-
-
 class UserTopic(models.Model):
     user_profile = models.ForeignKey(UserProfile, on_delete=CASCADE)
     stream = models.ForeignKey(Stream, on_delete=CASCADE)
@@ -489,61 +292,6 @@ def get_client_remote_cache(name: str) -> Client:
     return client
 
 
-def get_realm_stream(stream_name: str, realm_id: int) -> Stream:
-    return Stream.objects.get(name__iexact=stream_name.strip(), realm_id=realm_id)
-
-
-def get_active_streams(realm: Realm) -> QuerySet[Stream]:
-    """
-    Return all streams (including invite-only streams) that have not been deactivated.
-    """
-    return Stream.objects.filter(realm=realm, deactivated=False)
-
-
-def get_linkable_streams(realm_id: int) -> QuerySet[Stream]:
-    """
-    This returns the streams that we are allowed to linkify using
-    something like "#frontend" in our markup. For now the business
-    rule is that you can link any stream in the realm that hasn't
-    been deactivated (similar to how get_active_streams works).
-    """
-    return Stream.objects.filter(realm_id=realm_id, deactivated=False)
-
-
-def get_stream(stream_name: str, realm: Realm) -> Stream:
-    """
-    Callers that don't have a Realm object already available should use
-    get_realm_stream directly, to avoid unnecessarily fetching the
-    Realm object.
-    """
-    return get_realm_stream(stream_name, realm.id)
-
-
-def get_stream_by_id_in_realm(stream_id: int, realm: Realm) -> Stream:
-    return Stream.objects.select_related("realm", "recipient").get(id=stream_id, realm=realm)
-
-
-def bulk_get_streams(realm: Realm, stream_names: Set[str]) -> Dict[str, Any]:
-    def fetch_streams_by_name(stream_names: Set[str]) -> QuerySet[Stream]:
-        #
-        # This should be just
-        #
-        # Stream.objects.select_related().filter(name__iexact__in=stream_names,
-        #                                        realm_id=realm_id)
-        #
-        # But chaining __in and __iexact doesn't work with Django's
-        # ORM, so we have the following hack to construct the relevant where clause
-        where_clause = (
-            "upper(zerver_stream.name::text) IN (SELECT upper(name) FROM unnest(%s) AS name)"
-        )
-        return get_active_streams(realm).extra(where=[where_clause], params=(list(stream_names),))
-
-    if not stream_names:
-        return {}
-    streams = list(fetch_streams_by_name(stream_names))
-    return {stream.name.lower(): stream for stream in streams}
-
-
 class AbstractMessage(models.Model):
     sender = models.ForeignKey(UserProfile, on_delete=CASCADE)
 
@@ -1432,91 +1180,6 @@ def get_old_unclaimed_attachments(
     return old_attachments, old_archived_attachments
 
 
-class Subscription(models.Model):
-    """Keeps track of which users are part of the
-    audience for a given Recipient object.
-
-    For 1:1 and group direct message Recipient objects, only the
-    user_profile and recipient fields have any meaning, defining the
-    immutable set of users who are in the audience for that Recipient.
-
-    For Recipient objects associated with a Stream, the remaining
-    fields in this model describe the user's subscription to that stream.
-    """
-
-    user_profile = models.ForeignKey(UserProfile, on_delete=CASCADE)
-    recipient = models.ForeignKey(Recipient, on_delete=CASCADE)
-
-    # Whether the user has since unsubscribed.  We mark Subscription
-    # objects as inactive, rather than deleting them, when a user
-    # unsubscribes, so we can preserve user customizations like
-    # notification settings, stream color, etc., if the user later
-    # resubscribes.
-    active = models.BooleanField(default=True)
-    # This is a denormalization designed to improve the performance of
-    # bulk queries of Subscription objects, Whether the subscribed user
-    # is active tends to be a key condition in those queries.
-    # We intentionally don't specify a default value to promote thinking
-    # about this explicitly, as in some special cases, such as data import,
-    # we may be creating Subscription objects for a user that's deactivated.
-    is_user_active = models.BooleanField()
-
-    # Whether this user had muted this stream.
-    is_muted = models.BooleanField(default=False)
-
-    DEFAULT_STREAM_COLOR = "#c2c2c2"
-    color = models.CharField(max_length=10, default=DEFAULT_STREAM_COLOR)
-    pin_to_top = models.BooleanField(default=False)
-
-    # These fields are stream-level overrides for the user's default
-    # configuration for notification, configured in UserProfile.  The
-    # default, None, means we just inherit the user-level default.
-    desktop_notifications = models.BooleanField(null=True, default=None)
-    audible_notifications = models.BooleanField(null=True, default=None)
-    push_notifications = models.BooleanField(null=True, default=None)
-    email_notifications = models.BooleanField(null=True, default=None)
-    wildcard_mentions_notify = models.BooleanField(null=True, default=None)
-
-    class Meta:
-        unique_together = ("user_profile", "recipient")
-        indexes = [
-            models.Index(
-                fields=("recipient", "user_profile"),
-                name="zerver_subscription_recipient_id_user_profile_id_idx",
-                condition=Q(active=True, is_user_active=True),
-            ),
-        ]
-
-    @override
-    def __str__(self) -> str:
-        return f"{self.user_profile!r} -> {self.recipient!r}"
-
-    # Subscription fields included whenever a Subscription object is provided to
-    # Zulip clients via the API.  A few details worth noting:
-    # * These fields will generally be merged with Stream.API_FIELDS
-    #   data about the stream.
-    # * "user_profile" is usually implied as full API access to Subscription
-    #   is primarily done for the current user; API access to other users'
-    #   subscriptions is generally limited to boolean yes/no.
-    # * "id" and "recipient_id" are not included as they are not used
-    #   in the Zulip API; it's an internal implementation detail.
-    #   Subscription objects are always looked up in the API via
-    #   (user_profile, stream) pairs.
-    # * "active" is often excluded in API use cases where it is implied.
-    # * "is_muted" often needs to be copied to not "in_home_view" for
-    #   backwards-compatibility.
-    API_FIELDS = [
-        "audible_notifications",
-        "color",
-        "desktop_notifications",
-        "email_notifications",
-        "is_muted",
-        "pin_to_top",
-        "push_notifications",
-        "wildcard_mentions_notify",
-    ]
-
-
 class UserActivity(models.Model):
     """Data table recording the last time each user hit Zulip endpoints
     via which Clients; unlike UserPresence, these data are not exposed
@@ -1627,38 +1290,6 @@ class UserStatus(AbstractEmoji):
     status_text = models.CharField(max_length=255, default="")
 
 
-class DefaultStream(models.Model):
-    realm = models.ForeignKey(Realm, on_delete=CASCADE)
-    stream = models.ForeignKey(Stream, on_delete=CASCADE)
-
-    class Meta:
-        unique_together = ("realm", "stream")
-
-
-class DefaultStreamGroup(models.Model):
-    MAX_NAME_LENGTH = 60
-
-    name = models.CharField(max_length=MAX_NAME_LENGTH, db_index=True)
-    realm = models.ForeignKey(Realm, on_delete=CASCADE)
-    streams = models.ManyToManyField("zerver.Stream")
-    description = models.CharField(max_length=1024, default="")
-
-    class Meta:
-        unique_together = ("realm", "name")
-
-    def to_dict(self) -> Dict[str, Any]:
-        return dict(
-            name=self.name,
-            id=self.id,
-            description=self.description,
-            streams=[stream.to_dict() for stream in self.streams.all().order_by("name")],
-        )
-
-
-def get_default_stream_groups(realm: Realm) -> QuerySet[DefaultStreamGroup]:
-    return DefaultStreamGroup.objects.filter(realm=realm)
-
-
 class AbstractScheduledJob(models.Model):
     scheduled_timestamp = models.DateTimeField(db_index=True)
     # JSON representation of arguments to consumer

zerver/models/streams.py

@@ -0,0 +1,387 @@
+import secrets
+from typing import Any, Dict, Set
+
+from django.db import models
+from django.db.models import CASCADE, Q, QuerySet
+from django.db.models.functions import Upper
+from django.db.models.signals import post_delete, post_save
+from django.utils.timezone import now as timezone_now
+from django.utils.translation import gettext_lazy
+from django_stubs_ext import StrPromise
+from typing_extensions import override
+
+from zerver.lib.cache import flush_stream
+from zerver.lib.timestamp import datetime_to_timestamp
+from zerver.lib.types import DefaultStreamDict, GroupPermissionSetting
+from zerver.models.groups import SystemGroups, UserGroup
+from zerver.models.realms import Realm
+from zerver.models.recipients import Recipient
+from zerver.models.users import UserProfile
+
+
+def generate_email_token_for_stream() -> str:
+    return secrets.token_hex(16)
+
+
+class Stream(models.Model):
+    MAX_NAME_LENGTH = 60
+    MAX_DESCRIPTION_LENGTH = 1024
+
+    name = models.CharField(max_length=MAX_NAME_LENGTH, db_index=True)
+    realm = models.ForeignKey(Realm, db_index=True, on_delete=CASCADE)
+    date_created = models.DateTimeField(default=timezone_now)
+    deactivated = models.BooleanField(default=False)
+    description = models.CharField(max_length=MAX_DESCRIPTION_LENGTH, default="")
+    rendered_description = models.TextField(default="")
+
+    # Foreign key to the Recipient object for STREAM type messages to this stream.
+    recipient = models.ForeignKey(Recipient, null=True, on_delete=models.SET_NULL)
+
+    # Various permission policy configurations
+    PERMISSION_POLICIES: Dict[str, Dict[str, Any]] = {
+        "web_public": {
+            "invite_only": False,
+            "history_public_to_subscribers": True,
+            "is_web_public": True,
+            "policy_name": gettext_lazy("Web-public"),
+        },
+        "public": {
+            "invite_only": False,
+            "history_public_to_subscribers": True,
+            "is_web_public": False,
+            "policy_name": gettext_lazy("Public"),
+        },
+        "private_shared_history": {
+            "invite_only": True,
+            "history_public_to_subscribers": True,
+            "is_web_public": False,
+            "policy_name": gettext_lazy("Private, shared history"),
+        },
+        "private_protected_history": {
+            "invite_only": True,
+            "history_public_to_subscribers": False,
+            "is_web_public": False,
+            "policy_name": gettext_lazy("Private, protected history"),
+        },
+        # Public streams with protected history are currently only
+        # available in Zephyr realms
+        "public_protected_history": {
+            "invite_only": False,
+            "history_public_to_subscribers": False,
+            "is_web_public": False,
+            "policy_name": gettext_lazy("Public, protected history"),
+        },
+    }
+    invite_only = models.BooleanField(default=False)
+    history_public_to_subscribers = models.BooleanField(default=True)
+
+    # Whether this stream's content should be published by the web-public archive features
+    is_web_public = models.BooleanField(default=False)
+
+    STREAM_POST_POLICY_EVERYONE = 1
+    STREAM_POST_POLICY_ADMINS = 2
+    STREAM_POST_POLICY_RESTRICT_NEW_MEMBERS = 3
+    STREAM_POST_POLICY_MODERATORS = 4
+    # TODO: Implement policy to restrict posting to a user group or admins.
+
+    # Who in the organization has permission to send messages to this stream.
+    stream_post_policy = models.PositiveSmallIntegerField(default=STREAM_POST_POLICY_EVERYONE)
+    POST_POLICIES: Dict[int, StrPromise] = {
+        # These strings should match the strings in the
+        # stream_post_policy_values object in stream_data.js.
+        STREAM_POST_POLICY_EVERYONE: gettext_lazy("All stream members can post"),
+        STREAM_POST_POLICY_ADMINS: gettext_lazy("Only organization administrators can post"),
+        STREAM_POST_POLICY_MODERATORS: gettext_lazy(
+            "Only organization administrators and moderators can post"
+        ),
+        STREAM_POST_POLICY_RESTRICT_NEW_MEMBERS: gettext_lazy(
+            "Only organization full members can post"
+        ),
+    }
+    STREAM_POST_POLICY_TYPES = list(POST_POLICIES.keys())
+
+    # The unique thing about Zephyr public streams is that we never list their
+    # users.  We may try to generalize this concept later, but for now
+    # we just use a concrete field.  (Zephyr public streams aren't exactly like
+    # invite-only streams--while both are private in terms of listing users,
+    # for Zephyr we don't even list users to stream members, yet membership
+    # is more public in the sense that you don't need a Zulip invite to join.
+    # This field is populated directly from UserProfile.is_zephyr_mirror_realm,
+    # and the reason for denormalizing field is performance.
+    is_in_zephyr_realm = models.BooleanField(default=False)
+
+    # Used by the e-mail forwarder. The e-mail RFC specifies a maximum
+    # e-mail length of 254, and our max stream length is 30, so we
+    # have plenty of room for the token.
+    email_token = models.CharField(
+        max_length=32,
+        default=generate_email_token_for_stream,
+        unique=True,
+    )
+
+    # For old messages being automatically deleted.
+    # Value NULL means "use retention policy of the realm".
+    # Value -1 means "disable retention policy for this stream unconditionally".
+    # Non-negative values have the natural meaning of "archive messages older than <value> days".
+    MESSAGE_RETENTION_SPECIAL_VALUES_MAP = {
+        "unlimited": -1,
+        "realm_default": None,
+    }
+    message_retention_days = models.IntegerField(null=True, default=None)
+
+    # on_delete field here is set to RESTRICT because we don't want to allow
+    # deleting a user group in case it is referenced by this setting.
+    # We are not using PROTECT since we want to allow deletion of user groups
+    # when realm itself is deleted.
+    can_remove_subscribers_group = models.ForeignKey(UserGroup, on_delete=models.RESTRICT)
+
+    # The very first message ID in the stream.  Used to help clients
+    # determine whether they might need to display "more topics" for a
+    # stream based on what messages they have cached.
+    first_message_id = models.IntegerField(null=True, db_index=True)
+
+    stream_permission_group_settings = {
+        "can_remove_subscribers_group": GroupPermissionSetting(
+            require_system_group=True,
+            allow_internet_group=False,
+            allow_owners_group=False,
+            allow_nobody_group=False,
+            allow_everyone_group=True,
+            default_group_name=SystemGroups.ADMINISTRATORS,
+            id_field_name="can_remove_subscribers_group_id",
+        ),
+    }
+
+    class Meta:
+        indexes = [
+            models.Index(Upper("name"), name="upper_stream_name_idx"),
+        ]
+
+    @override
+    def __str__(self) -> str:
+        return self.name
+
+    def is_public(self) -> bool:
+        # All streams are private in Zephyr mirroring realms.
+        return not self.invite_only and not self.is_in_zephyr_realm
+
+    def is_history_realm_public(self) -> bool:
+        return self.is_public()
+
+    def is_history_public_to_subscribers(self) -> bool:
+        return self.history_public_to_subscribers
+
+    # Stream fields included whenever a Stream object is provided to
+    # Zulip clients via the API.  A few details worth noting:
+    # * "id" is represented as "stream_id" in most API interfaces.
+    # * "email_token" is not realm-public and thus is not included here.
+    # * is_in_zephyr_realm is a backend-only optimization.
+    # * "deactivated" streams are filtered from the API entirely.
+    # * "realm" and "recipient" are not exposed to clients via the API.
+    API_FIELDS = [
+        "date_created",
+        "description",
+        "first_message_id",
+        "history_public_to_subscribers",
+        "id",
+        "invite_only",
+        "is_web_public",
+        "message_retention_days",
+        "name",
+        "rendered_description",
+        "stream_post_policy",
+        "can_remove_subscribers_group_id",
+    ]
+
+    def to_dict(self) -> DefaultStreamDict:
+        return DefaultStreamDict(
+            can_remove_subscribers_group=self.can_remove_subscribers_group_id,
+            date_created=datetime_to_timestamp(self.date_created),
+            description=self.description,
+            first_message_id=self.first_message_id,
+            history_public_to_subscribers=self.history_public_to_subscribers,
+            invite_only=self.invite_only,
+            is_web_public=self.is_web_public,
+            message_retention_days=self.message_retention_days,
+            name=self.name,
+            rendered_description=self.rendered_description,
+            stream_id=self.id,
+            stream_post_policy=self.stream_post_policy,
+            is_announcement_only=self.stream_post_policy == Stream.STREAM_POST_POLICY_ADMINS,
+        )
+
+
+post_save.connect(flush_stream, sender=Stream)
+post_delete.connect(flush_stream, sender=Stream)
+
+
+def get_realm_stream(stream_name: str, realm_id: int) -> Stream:
+    return Stream.objects.get(name__iexact=stream_name.strip(), realm_id=realm_id)
+
+
+def get_active_streams(realm: Realm) -> QuerySet[Stream]:
+    """
+    Return all streams (including invite-only streams) that have not been deactivated.
+    """
+    return Stream.objects.filter(realm=realm, deactivated=False)
+
+
+def get_linkable_streams(realm_id: int) -> QuerySet[Stream]:
+    """
+    This returns the streams that we are allowed to linkify using
+    something like "#frontend" in our markup. For now the business
+    rule is that you can link any stream in the realm that hasn't
+    been deactivated (similar to how get_active_streams works).
+    """
+    return Stream.objects.filter(realm_id=realm_id, deactivated=False)
+
+
+def get_stream(stream_name: str, realm: Realm) -> Stream:
+    """
+    Callers that don't have a Realm object already available should use
+    get_realm_stream directly, to avoid unnecessarily fetching the
+    Realm object.
+    """
+    return get_realm_stream(stream_name, realm.id)
+
+
+def get_stream_by_id_in_realm(stream_id: int, realm: Realm) -> Stream:
+    return Stream.objects.select_related("realm", "recipient").get(id=stream_id, realm=realm)
+
+
+def bulk_get_streams(realm: Realm, stream_names: Set[str]) -> Dict[str, Any]:
+    def fetch_streams_by_name(stream_names: Set[str]) -> QuerySet[Stream]:
+        #
+        # This should be just
+        #
+        # Stream.objects.select_related().filter(name__iexact__in=stream_names,
+        #                                        realm_id=realm_id)
+        #
+        # But chaining __in and __iexact doesn't work with Django's
+        # ORM, so we have the following hack to construct the relevant where clause
+        where_clause = (
+            "upper(zerver_stream.name::text) IN (SELECT upper(name) FROM unnest(%s) AS name)"
+        )
+        return get_active_streams(realm).extra(where=[where_clause], params=(list(stream_names),))
+
+    if not stream_names:
+        return {}
+    streams = list(fetch_streams_by_name(stream_names))
+    return {stream.name.lower(): stream for stream in streams}
+
+
+class Subscription(models.Model):
+    """Keeps track of which users are part of the
+    audience for a given Recipient object.
+
+    For 1:1 and group direct message Recipient objects, only the
+    user_profile and recipient fields have any meaning, defining the
+    immutable set of users who are in the audience for that Recipient.
+
+    For Recipient objects associated with a Stream, the remaining
+    fields in this model describe the user's subscription to that stream.
+    """
+
+    user_profile = models.ForeignKey(UserProfile, on_delete=CASCADE)
+    recipient = models.ForeignKey(Recipient, on_delete=CASCADE)
+
+    # Whether the user has since unsubscribed.  We mark Subscription
+    # objects as inactive, rather than deleting them, when a user
+    # unsubscribes, so we can preserve user customizations like
+    # notification settings, stream color, etc., if the user later
+    # resubscribes.
+    active = models.BooleanField(default=True)
+    # This is a denormalization designed to improve the performance of
+    # bulk queries of Subscription objects, Whether the subscribed user
+    # is active tends to be a key condition in those queries.
+    # We intentionally don't specify a default value to promote thinking
+    # about this explicitly, as in some special cases, such as data import,
+    # we may be creating Subscription objects for a user that's deactivated.
+    is_user_active = models.BooleanField()
+
+    # Whether this user had muted this stream.
+    is_muted = models.BooleanField(default=False)
+
+    DEFAULT_STREAM_COLOR = "#c2c2c2"
+    color = models.CharField(max_length=10, default=DEFAULT_STREAM_COLOR)
+    pin_to_top = models.BooleanField(default=False)
+
+    # These fields are stream-level overrides for the user's default
+    # configuration for notification, configured in UserProfile.  The
+    # default, None, means we just inherit the user-level default.
+    desktop_notifications = models.BooleanField(null=True, default=None)
+    audible_notifications = models.BooleanField(null=True, default=None)
+    push_notifications = models.BooleanField(null=True, default=None)
+    email_notifications = models.BooleanField(null=True, default=None)
+    wildcard_mentions_notify = models.BooleanField(null=True, default=None)
+
+    class Meta:
+        unique_together = ("user_profile", "recipient")
+        indexes = [
+            models.Index(
+                fields=("recipient", "user_profile"),
+                name="zerver_subscription_recipient_id_user_profile_id_idx",
+                condition=Q(active=True, is_user_active=True),
+            ),
+        ]
+
+    @override
+    def __str__(self) -> str:
+        return f"{self.user_profile!r} -> {self.recipient!r}"
+
+    # Subscription fields included whenever a Subscription object is provided to
+    # Zulip clients via the API.  A few details worth noting:
+    # * These fields will generally be merged with Stream.API_FIELDS
+    #   data about the stream.
+    # * "user_profile" is usually implied as full API access to Subscription
+    #   is primarily done for the current user; API access to other users'
+    #   subscriptions is generally limited to boolean yes/no.
+    # * "id" and "recipient_id" are not included as they are not used
+    #   in the Zulip API; it's an internal implementation detail.
+    #   Subscription objects are always looked up in the API via
+    #   (user_profile, stream) pairs.
+    # * "active" is often excluded in API use cases where it is implied.
+    # * "is_muted" often needs to be copied to not "in_home_view" for
+    #   backwards-compatibility.
+    API_FIELDS = [
+        "audible_notifications",
+        "color",
+        "desktop_notifications",
+        "email_notifications",
+        "is_muted",
+        "pin_to_top",
+        "push_notifications",
+        "wildcard_mentions_notify",
+    ]
+
+
+class DefaultStream(models.Model):
+    realm = models.ForeignKey(Realm, on_delete=CASCADE)
+    stream = models.ForeignKey(Stream, on_delete=CASCADE)
+
+    class Meta:
+        unique_together = ("realm", "stream")
+
+
+class DefaultStreamGroup(models.Model):
+    MAX_NAME_LENGTH = 60
+
+    name = models.CharField(max_length=MAX_NAME_LENGTH, db_index=True)
+    realm = models.ForeignKey(Realm, on_delete=CASCADE)
+    streams = models.ManyToManyField("zerver.Stream")
+    description = models.CharField(max_length=1024, default="")
+
+    class Meta:
+        unique_together = ("realm", "name")
+
+    def to_dict(self) -> Dict[str, Any]:
+        return dict(
+            name=self.name,
+            id=self.id,
+            description=self.description,
+            streams=[stream.to_dict() for stream in self.streams.all().order_by("name")],
+        )
+
+
+def get_default_stream_groups(realm: Realm) -> QuerySet[DefaultStreamGroup]:
+    return DefaultStreamGroup.objects.filter(realm=realm)

zerver/tests/test_audit_log.py

@@ -81,13 +81,13 @@ from zerver.models import (
     Subscription,
     UserGroup,
     UserProfile,
-    get_stream,
 )
 from zerver.models.groups import SystemGroups
 from zerver.models.linkifiers import linkifiers_for_realm
 from zerver.models.realm_emoji import EmojiInfo, get_all_custom_emoji_for_realm
 from zerver.models.realm_playgrounds import get_realm_playgrounds
 from zerver.models.realms import RealmDomainDict, get_realm, get_realm_domains
+from zerver.models.streams import get_stream
 
 
 class TestRealmAuditLog(ZulipTestCase):

zerver/tests/test_bots.py

@@ -24,9 +24,9 @@ from zerver.models import (
     Subscription,
     UserProfile,
     get_bot_services,
-    get_stream,
 )
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 from zerver.models.users import get_user, is_cross_realm_bot_email
 
 

zerver/tests/test_digest.py

@@ -26,16 +26,9 @@ from zerver.lib.digest import (
 from zerver.lib.message import get_last_message_id
 from zerver.lib.streams import create_stream_if_needed
 from zerver.lib.test_classes import ZulipTestCase
-from zerver.models import (
+from zerver.models import Message, Realm, RealmAuditLog, Stream, UserActivityInterval, UserProfile
-    Message,
-    Realm,
-    RealmAuditLog,
-    Stream,
-    UserActivityInterval,
-    UserProfile,
-    get_stream,
-)
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 
 
 class TestDigestEmailMessages(ZulipTestCase):

zerver/tests/test_email_mirror.py

@@ -37,8 +37,9 @@ from zerver.lib.send_email import FromAddress
 from zerver.lib.streams import ensure_stream
 from zerver.lib.test_classes import ZulipTestCase
 from zerver.lib.test_helpers import mock_queue_publish, most_recent_message, most_recent_usermessage
-from zerver.models import Attachment, Recipient, Stream, UserProfile, get_stream
+from zerver.models import Attachment, Recipient, Stream, UserProfile
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 from zerver.models.users import get_system_bot
 from zerver.worker.queue_processors import MirrorWorker
 

zerver/tests/test_event_queue.py

@@ -15,7 +15,8 @@ from zerver.actions.user_topics import do_set_user_topic_visibility_policy
 from zerver.lib.cache import cache_delete, get_muting_users_cache_key
 from zerver.lib.test_classes import ZulipTestCase
 from zerver.lib.test_helpers import HostRequestMock, dummy_handler, mock_queue_publish
-from zerver.models import Recipient, Subscription, UserProfile, UserTopic, get_stream
+from zerver.models import Recipient, Subscription, UserProfile, UserTopic
+from zerver.models.streams import get_stream
 from zerver.tornado.event_queue import (
     ClientDescriptor,
     access_client_descriptor,

zerver/tests/test_event_system.py

@@ -28,15 +28,9 @@ from zerver.lib.test_helpers import (
     stub_event_queue_user_events,
 )
 from zerver.lib.users import get_api_key, get_users_for_api
-from zerver.models import (
+from zerver.models import CustomProfileField, UserMessage, UserPresence, UserProfile, get_client
-    CustomProfileField,
-    UserMessage,
-    UserPresence,
-    UserProfile,
-    get_client,
-    get_stream,
-)
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 from zerver.models.users import get_system_bot
 from zerver.tornado.event_queue import (
     allocate_client_descriptor,

zerver/tests/test_events.py

@@ -241,9 +241,9 @@ from zerver.models import (
     UserStatus,
     UserTopic,
     get_client,
-    get_stream,
 )
 from zerver.models.groups import SystemGroups
+from zerver.models.streams import get_stream
 from zerver.models.users import get_user_by_delivery_email
 from zerver.openapi.openapi import validate_against_openapi_schema
 from zerver.tornado.django_api import send_event

zerver/tests/test_example.py

@@ -11,8 +11,9 @@ from zerver.lib.streams import access_stream_for_send_message
 from zerver.lib.test_classes import ZulipTestCase
 from zerver.lib.test_helpers import most_recent_message
 from zerver.lib.users import is_administrator_role
-from zerver.models import UserProfile, UserStatus, get_stream
+from zerver.models import UserProfile, UserStatus
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 from zerver.models.users import get_user_by_delivery_email
 
 

zerver/tests/test_home.py

@@ -24,8 +24,9 @@ from zerver.lib.soft_deactivation import do_soft_deactivate_users
 from zerver.lib.test_classes import ZulipTestCase
 from zerver.lib.test_helpers import get_user_messages, queries_captured
 from zerver.lib.timestamp import datetime_to_timestamp
-from zerver.models import DefaultStream, Draft, Realm, UserActivity, UserProfile, get_stream
+from zerver.models import DefaultStream, Draft, Realm, UserActivity, UserProfile
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 from zerver.models.users import get_system_bot, get_user
 from zerver.worker.queue_processors import UserActivityWorker
 

zerver/tests/test_i18n.py

@@ -13,7 +13,7 @@ from zerver.lib.i18n import get_browser_language_code
 from zerver.lib.test_classes import ZulipTestCase
 from zerver.lib.test_helpers import HostRequestMock
 from zerver.management.commands import makemessages
-from zerver.models import get_realm_stream
+from zerver.models.streams import get_realm_stream
 
 if TYPE_CHECKING:
     from django.test.client import _MonkeyPatchedWSGIResponse as TestHttpResponse

zerver/tests/test_import_export.py

@@ -83,13 +83,12 @@ from zerver.models import (
     UserProfile,
     UserStatus,
     UserTopic,
-    get_active_streams,
     get_client,
-    get_stream,
 )
 from zerver.models.groups import SystemGroups
 from zerver.models.realms import get_realm
 from zerver.models.recipients import get_huddle_hash
+from zerver.models.streams import get_active_streams, get_stream
 from zerver.models.users import get_system_bot, get_user_by_delivery_email
 
 

zerver/tests/test_invite.py

@@ -63,10 +63,10 @@ from zerver.models import (
     UserGroup,
     UserMessage,
     UserProfile,
-    get_stream,
 )
 from zerver.models.groups import SystemGroups
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 from zerver.models.users import get_user_by_delivery_email
 from zerver.views.invite import INVITATION_LINK_VALIDITY_MINUTES, get_invitee_emails_set
 from zerver.views.registration import accounts_home

zerver/tests/test_management_commands.py

@@ -20,8 +20,9 @@ from zerver.actions.reactions import do_add_reaction
 from zerver.lib.management import ZulipBaseCommand, check_config
 from zerver.lib.test_classes import ZulipTestCase
 from zerver.lib.test_helpers import most_recent_message, stdout_suppressed
-from zerver.models import Message, Reaction, Realm, Recipient, UserProfile, get_stream
+from zerver.models import Message, Reaction, Realm, Recipient, UserProfile
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 from zerver.models.users import get_user_profile_by_email
 
 

zerver/tests/test_markdown.py

@@ -68,11 +68,11 @@ from zerver.models import (
     UserMessage,
     UserProfile,
     get_client,
-    get_stream,
 )
 from zerver.models.groups import SystemGroups
 from zerver.models.linkifiers import linkifiers_for_realm
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 
 
 class SimulatedFencedBlockPreprocessor(FencedBlockPreprocessor):

zerver/tests/test_message_dict.py

@@ -12,17 +12,9 @@ from zerver.lib.test_classes import ZulipTestCase
 from zerver.lib.test_helpers import make_client
 from zerver.lib.topic import TOPIC_LINKS
 from zerver.lib.types import DisplayRecipientT, UserDisplayRecipient
-from zerver.models import (
+from zerver.models import Message, Reaction, Realm, RealmFilter, Recipient, Stream, UserProfile
-    Message,
-    Reaction,
-    Realm,
-    RealmFilter,
-    Recipient,
-    Stream,
-    UserProfile,
-    get_stream,
-)
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 
 
 class MessageDictTest(ZulipTestCase):

zerver/tests/test_message_edit.py

@@ -30,19 +30,11 @@ from zerver.lib.user_topics import (
     topic_has_visibility_policy,
 )
 from zerver.lib.utils import assert_is_not_none
-from zerver.models import (
+from zerver.models import Message, Realm, Stream, UserGroup, UserMessage, UserProfile, UserTopic
-    Message,
-    Realm,
-    Stream,
-    UserGroup,
-    UserMessage,
-    UserProfile,
-    UserTopic,
-    get_stream,
-)
 from zerver.models.constants import MAX_TOPIC_NAME_LENGTH
 from zerver.models.groups import SystemGroups
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 
 if TYPE_CHECKING:
     from django.test.client import _MonkeyPatchedWSGIResponse as TestHttpResponse

zerver/tests/test_message_edit_notifications.py

@@ -8,7 +8,8 @@ from zerver.actions.user_topics import do_set_user_topic_visibility_policy
 from zerver.lib.push_notifications import get_apns_badge_count, get_apns_badge_count_future
 from zerver.lib.test_classes import ZulipTestCase
 from zerver.lib.test_helpers import mock_queue_publish
-from zerver.models import NotificationTriggers, Subscription, UserPresence, UserTopic, get_stream
+from zerver.models import NotificationTriggers, Subscription, UserPresence, UserTopic
+from zerver.models.streams import get_stream
 from zerver.tornado.event_queue import maybe_enqueue_notifications
 
 

zerver/tests/test_message_fetch.py

@@ -58,9 +58,9 @@ from zerver.models import (
     UserMessage,
     UserProfile,
     UserTopic,
-    get_stream,
 )
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 from zerver.views.message_fetch import get_messages_backend
 
 if TYPE_CHECKING:

zerver/tests/test_message_flags.py

@@ -33,9 +33,9 @@ from zerver.models import (
     UserMessage,
     UserProfile,
     UserTopic,
-    get_stream,
 )
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 
 if TYPE_CHECKING:
     from django.test.client import _MonkeyPatchedWSGIResponse as TestHttpResponse

zerver/tests/test_message_notification_emails.py

@@ -27,9 +27,10 @@ from zerver.lib.email_notifications import (
 )
 from zerver.lib.send_email import FromAddress
 from zerver.lib.test_classes import ZulipTestCase
-from zerver.models import NotificationTriggers, UserMessage, UserProfile, UserTopic, get_stream
+from zerver.models import NotificationTriggers, UserMessage, UserProfile, UserTopic
 from zerver.models.realm_emoji import get_name_keyed_dict_for_active_realm_emoji
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 
 
 class TestMessageNotificationEmails(ZulipTestCase):

zerver/tests/test_message_send.py

@@ -56,12 +56,12 @@ from zerver.models import (
     UserGroup,
     UserMessage,
     UserProfile,
-    get_stream,
 )
 from zerver.models.constants import MAX_TOPIC_NAME_LENGTH
 from zerver.models.groups import SystemGroups
 from zerver.models.realms import get_realm
 from zerver.models.recipients import get_or_create_huddle
+from zerver.models.streams import get_stream
 from zerver.models.users import get_system_bot, get_user
 from zerver.views.message_send import InvalidMirrorInputError
 

zerver/tests/test_message_topics.py

@@ -6,8 +6,9 @@ from zerver.actions.streams import do_change_stream_permission
 from zerver.lib.test_classes import ZulipTestCase
 from zerver.lib.test_helpers import timeout_mock
 from zerver.lib.timeout import TimeoutExpiredError
-from zerver.models import Message, UserMessage, get_client, get_stream
+from zerver.models import Message, UserMessage, get_client
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 
 
 class TopicHistoryTest(ZulipTestCase):

zerver/tests/test_outgoing_webhook_interfaces.py

@@ -12,8 +12,9 @@ from zerver.lib.outgoing_webhook import get_service_interface_class, process_suc
 from zerver.lib.test_classes import ZulipTestCase
 from zerver.lib.timestamp import datetime_to_timestamp
 from zerver.lib.topic import TOPIC_NAME
-from zerver.models import SLACK_INTERFACE, Message, NotificationTriggers, get_stream
+from zerver.models import SLACK_INTERFACE, Message, NotificationTriggers
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 from zerver.models.users import get_user
 from zerver.openapi.openapi import validate_against_openapi_schema
 

zerver/tests/test_outgoing_webhook_system.py

@@ -19,8 +19,9 @@ from zerver.lib.test_classes import ZulipTestCase
 from zerver.lib.topic import TOPIC_NAME
 from zerver.lib.url_encoding import near_message_url
 from zerver.lib.users import add_service
-from zerver.models import Recipient, Service, UserProfile, get_stream
+from zerver.models import Recipient, Service, UserProfile
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 
 
 class ResponseMock:

zerver/tests/test_push_notifications.py

@@ -91,9 +91,9 @@ from zerver.models import (
     UserProfile,
     UserTopic,
     get_client,
-    get_stream,
 )
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 from zilencer.models import RemoteZulipServerAuditLog
 from zilencer.views import DevicesToCleanUpDict
 

zerver/tests/test_queue_worker.py

@@ -32,9 +32,9 @@ from zerver.models import (
     UserActivity,
     UserProfile,
     get_client,
-    get_stream,
 )
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 from zerver.tornado.event_queue import build_offline_notification
 from zerver.worker import queue_processors
 from zerver.worker.queue_processors import (

zerver/tests/test_realm.py

@@ -53,10 +53,10 @@ from zerver.models import (
     UserGroupMembership,
     UserMessage,
     UserProfile,
-    get_stream,
 )
 from zerver.models.groups import SystemGroups
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 from zerver.models.users import get_system_bot, get_user_profile_by_id
 
 

zerver/tests/test_retention.py

@@ -38,9 +38,9 @@ from zerver.models import (
     SubMessage,
     UserMessage,
     get_client,
-    get_stream,
 )
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 from zerver.models.users import get_system_bot
 
 # Class with helper functions useful for testing archiving of reactions:

zerver/tests/test_signup.py

@@ -76,9 +76,9 @@ from zerver.models import (
     Subscription,
     UserMessage,
     UserProfile,
-    get_stream,
 )
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 from zerver.models.users import get_system_bot, get_user, get_user_by_delivery_email
 from zerver.views.auth import redirect_and_log_into_subdomain, start_two_factor_auth
 from zerver.views.development.registration import confirmation_key

zerver/tests/test_soft_deactivation.py

@@ -27,9 +27,9 @@ from zerver.models import (
     UserActivity,
     UserMessage,
     UserProfile,
-    get_stream,
 )
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_stream
 
 logger_string = "zulip.soft_deactivation"
 

zerver/tests/test_subs.py

@@ -104,12 +104,11 @@ from zerver.models import (
     UserGroup,
     UserMessage,
     UserProfile,
-    get_default_stream_groups,
-    get_stream,
     validate_attachment_request,
     validate_attachment_request_for_spectator_access,
 )
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_default_stream_groups, get_stream
 from zerver.models.users import active_non_guest_user_ids, get_user, get_user_profile_by_id_in_realm
 from zerver.views.streams import compose_views
 

zerver/tests/test_user_topics.py

@@ -12,7 +12,8 @@ from zerver.lib.stream_topic import StreamTopicTarget
 from zerver.lib.test_classes import ZulipTestCase
 from zerver.lib.test_helpers import get_subscription
 from zerver.lib.user_topics import get_topic_mutes, topic_has_visibility_policy
-from zerver.models import UserProfile, UserTopic, get_stream
+from zerver.models import UserProfile, UserTopic
+from zerver.models.streams import get_stream
 
 
 class MutedTopicsTestsDeprecated(ZulipTestCase):

zerver/tests/test_users.py

@@ -74,11 +74,11 @@ from zerver.models import (
     UserTopic,
     check_valid_user_ids,
     get_client,
-    get_stream,
 )
 from zerver.models.groups import SystemGroups
 from zerver.models.prereg_users import filter_to_valid_prereg_users
 from zerver.models.realms import InvalidFakeEmailDomainError, get_fake_email_domain, get_realm
+from zerver.models.streams import get_stream
 from zerver.models.users import (
     get_source_profile,
     get_system_bot,

zerver/views/development/email_log.py

@@ -16,8 +16,9 @@ from zerver.actions.users import change_user_is_active
 from zerver.lib.email_notifications import enqueue_welcome_emails, send_account_registered_email
 from zerver.lib.request import REQ, has_request_variables
 from zerver.lib.response import json_success
-from zerver.models import Realm, get_realm_stream
+from zerver.models import Realm
 from zerver.models.realms import get_realm
+from zerver.models.streams import get_realm_stream
 from zerver.models.users import get_user_by_delivery_email
 from zerver.views.invite import INVITATION_LINK_VALIDITY_MINUTES
 from zproject.email_backends import get_forward_address, set_forward_address

zerver/views/registration.py

@@ -80,7 +80,6 @@ from zerver.models import (
     RealmUserDefault,
     Stream,
     UserProfile,
-    get_default_stream_groups,
 )
 from zerver.models.constants import MAX_LANGUAGE_ID_LENGTH
 from zerver.models.realms import (
@@ -91,6 +90,7 @@ from zerver.models.realms import (
     get_realm,
     name_changes_disabled,
 )
+from zerver.models.streams import get_default_stream_groups
 from zerver.models.users import get_source_profile, get_user_by_delivery_email
 from zerver.views.auth import (
     create_preregistration_realm,

zilencer/management/commands/populate_db.py

@@ -66,10 +66,10 @@ from zerver.models import (
     UserProfile,
     flush_alert_word,
     get_client,
-    get_stream,
 )
 from zerver.models.realms import get_realm
 from zerver.models.recipients import get_or_create_huddle
+from zerver.models.streams import get_stream
 from zerver.models.users import get_user, get_user_by_delivery_email, get_user_profile_by_id
 from zilencer.models import RemoteRealm, RemoteZulipServer
 from zilencer.views import update_remote_realm_data_for_server