realm-settings: Make default_code_block_language empty string as default.

Updates the realm field `default_code_block_language` to have a default
value of an empty string instead of None. Also updates the web-app to
check for the empty string and not `null` to indicate no default is set.

This means that both new realms and existing realms that have no default
set will have the same value for this setting: an empty string.

Previously, new realms would have None if no default was set, while realms
that had set and then unset a value for this field would have an empty
string when no default was set.

api_docs/changelog.md

@@ -20,6 +20,16 @@ format used by the Zulip server that they are interacting with.
 
 ## Changes in Zulip 8.0
 
+**Feature level 195**
+
+* [`GET /events`](/api/get-events), [`POST /register`](/api/register-queue):
+  The `default_code_block_language` realm setting is now consistently an
+  empty string when no default pygments language code is set. Previously,
+  the server had a bug that meant it might represent no default for this
+  realm setting as either `null` or an empty string. Clients supporting
+  older server versions should treat either value (`null` or `""`) as no
+  default being set.
+
 **Feature level 194**
 
 * [`GET /messages`](/api/get-messages),

version.py

@@ -33,7 +33,7 @@ DESKTOP_WARNING_VERSION = "5.9.3"
 # Changes should be accompanied by documentation explaining what the
 # new level means in api_docs/changelog.md, as well as "**Changes**"
 # entries in the endpoint's documentation in `zulip.yaml`.
-API_FEATURE_LEVEL = 194
+API_FEATURE_LEVEL = 195
 
 # Bump the minor PROVISION_VERSION to indicate that folks should provision
 # only when going from an old version of the code to a newer version. Bump

web/src/composebox_typeahead.js

@@ -1034,7 +1034,7 @@ function get_header_html() {
             tip_text = $t({defaultMessage: "Silent mentions do not trigger notifications."});
             break;
         case "syntax":
-            if (page_params.realm_default_code_block_language !== null) {
+            if (page_params.realm_default_code_block_language !== "") {
                 tip_text = $t(
                     {defaultMessage: "Default is {language}. Use 'text' to disable highlighting."},
                     {language: page_params.realm_default_code_block_language},

zerver/lib/event_schema.py

@@ -887,8 +887,6 @@ def check_realm_update(
         assert isinstance(value, property_type)
     elif property_type == (int, type(None)):
         assert isinstance(value, int)
-    elif property_type == (str, type(None)):
-        assert isinstance(value, str)
     else:
         raise AssertionError(f"Unexpected property type {property_type}")
 

zerver/migrations/0461_alter_realm_default_code_block_language.py

@@ -0,0 +1,39 @@
+# Generated by Django 4.2.2 on 2023-07-11 14:04
+
+from django.db import migrations, models
+from django.db.backends.base.schema import BaseDatabaseSchemaEditor
+from django.db.migrations.state import StateApps
+
+
+def set_default_code_block_language_to_empty_string(
+    apps: StateApps, schema_editor: BaseDatabaseSchemaEditor
+) -> None:
+    Realm = apps.get_model("zerver", "Realm")
+    Realm.objects.filter(default_code_block_language=None).update(default_code_block_language="")
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("zerver", "0460_backfill_realmauditlog_extradata_to_json_field"),
+    ]
+
+    operations = [
+        # Change default value from None to empty string for new realms
+        migrations.AlterField(
+            model_name="realm",
+            name="default_code_block_language",
+            field=models.TextField(null=True, default=""),
+        ),
+        # Update existing realms with None to have empty string
+        migrations.RunPython(
+            set_default_code_block_language_to_empty_string,
+            reverse_code=migrations.RunPython.noop,
+            elidable=True,
+        ),
+        # Remove null=True for this realm field
+        migrations.AlterField(
+            model_name="realm",
+            name="default_code_block_language",
+            field=models.TextField(default=""),
+        ),
+    ]

zerver/models.py

@@ -710,7 +710,7 @@ class Realm(models.Model):  # type: ignore[django-manager-missing] # django-stub
     # maximum rating of the GIFs that will be retrieved from GIPHY
     giphy_rating = models.PositiveSmallIntegerField(default=GIPHY_RATING_OPTIONS["g"]["id"])
 
-    default_code_block_language = models.TextField(null=True, default=None)
+    default_code_block_language = models.TextField(default="")
 
     # Whether read receipts are enabled in the organization. If disabled,
     # they will not be available regardless of users' personal settings.
@@ -726,7 +726,7 @@ class Realm(models.Model):  # type: ignore[django-manager-missing] # django-stub
         create_private_stream_policy=int,
         create_public_stream_policy=int,
         create_web_public_stream_policy=int,
-        default_code_block_language=(str, type(None)),
+        default_code_block_language=str,
         default_language=str,
         delete_own_message_policy=int,
         description=str,

zerver/openapi/zulip.yaml

@@ -3961,10 +3961,17 @@ paths:
                                         **Changes**: New in Zulip 5.0 (feature level 103).
                                     default_code_block_language:
                                       type: string
-                                      nullable: true
                                       description: |
-                                        The default pygments language code to be used for a code blocks
+                                        The default pygments language code to be used for code blocks in this
-                                        in this organization. If `null`, no default has been set.
+                                        organization. If an empty string, no default has been set.
+
+                                        **Changes**: Prior to Zulip 8.0 (feature level 195), a server bug meant
+                                        that both `null` and an empty string could represent that no default was
+                                        set for this realm setting in the [`POST /register`](/api/register-queue)
+                                        response. The documentation for both that endpoint and this event
+                                        incorrectly stated that the only representation for no default language
+                                        was `null`. This event in fact uses the empty string to indicate that no
+                                        default has been set in all server versions.
                                     default_language:
                                       type: string
                                       description: |
@@ -13339,12 +13346,16 @@ paths:
                           [calc-full-member]: /api/roles-and-permissions#determining-if-a-user-is-a-full-member
                       realm_default_code_block_language:
                         type: string
-                        nullable: true
                         description: |
                           Present if `realm` is present in `fetch_event_types`.
 
-                          The default pygments language code to be used for a code blocks
+                          The default pygments language code to be used for code blocks in this
-                          in this organization. If `null`, no default has been set.
+                          organization. If an empty string, no default has been set.
+
+                          **Changes**: Prior to Zulip 8.0 (feature level 195), a server bug meant
+                          that both `null` and an empty string could represent that no default was
+                          set for this realm setting. Clients supporting older server versions
+                          should treat either value (`null` or `""`) as no default being set.
                       realm_message_content_delete_limit_seconds:
                         type: integer
                         nullable: true

zerver/tests/test_markdown.py

@@ -1773,7 +1773,7 @@ class MarkdownTest(ZulipTestCase):
 
     def test_default_code_block_language(self) -> None:
         realm = get_realm("zulip")
-        self.assertEqual(realm.default_code_block_language, None)
+        self.assertEqual(realm.default_code_block_language, "")
         text = "```{}\nconsole.log('Hello World');\n```\n"
 
         # Render without default language
@@ -1803,7 +1803,7 @@ class MarkdownTest(ZulipTestCase):
         msg_without_language_default_math = markdown_convert_wrapper(text.format(""))
 
         # Render without default language
-        do_set_realm_property(realm, "default_code_block_language", None, acting_user=None)
+        do_set_realm_property(realm, "default_code_block_language", "", acting_user=None)
         msg_without_language_final = markdown_convert_wrapper(text.format(""))
 
         self.assertTrue(msg_with_js == msg_without_language_default_js)
@@ -1822,7 +1822,7 @@ class MarkdownTest(ZulipTestCase):
         with_language, without_language = re.findall(r"<pre>(.*?)$", rendered, re.MULTILINE)
         self.assertTrue(with_language == without_language)
 
-        do_set_realm_property(realm, "default_code_block_language", None, acting_user=None)
+        do_set_realm_property(realm, "default_code_block_language", "", acting_user=None)
         rendered = markdown_convert_wrapper(nested_text)
         with_language, without_language = re.findall(r"<pre>(.*?)$", rendered, re.MULTILINE)
         self.assertFalse(with_language == without_language)

zerver/views/realm.py

@@ -327,13 +327,6 @@ def update_realm(
         )
         data["signup_notifications_stream_id"] = signup_notifications_stream_id
 
-    if default_code_block_language is not None:
-        # Migrate '', used in the API to encode the default/None behavior of this feature.
-        if default_code_block_language == "":
-            data["default_code_block_language"] = None
-        else:
-            data["default_code_block_language"] = default_code_block_language
-
     if string_id is not None:
         if not user_profile.is_realm_owner:
             raise OrganizationOwnerRequiredError