user_groups: Add API endpoint to get members of a user group.

This commit adds 'GET /user_groups/{user_group_id}/members'
endpoint to get members of a user group. "direct_member_only"
parameter can be passed as True to the endpoint to get only
direct members of the user group and not the members of
subgroup.

templates/zerver/api/changelog.md

@@ -34,6 +34,8 @@ format used by the Zulip server that they are interacting with.
 * [`GET /user_groups/{user_group_id}/members/{user_id}`](/api/get-is-user-group-member):
   Added new endpoint for checking whether a given user is member of a
   given user group.
+* [`GET /user_groups/{user_group_id}/members`](/api/get-user-group-members):
+  Added new endpoint to get members of a user group.
 
 **Feature level 126**
 

templates/zerver/help/include/rest-endpoints.md

@@ -63,6 +63,7 @@
 * [Update user group members](/api/update-user-group-members)
 * [Update user group subgroups](/api/update-user-group-subgroups)
 * [Get user group membership status](/api/get-is-user-group-member)
+* [Get user group members](/api/get-user-group-members)
 * [Mute a user](/api/mute-user)
 * [Unmute a user](/api/unmute-user)
 

zerver/lib/user_groups.py

@@ -168,6 +168,17 @@ def is_user_in_group(
     return get_recursive_group_members(user_group=user_group).filter(id=user.id).exists()
 
 
+def get_user_group_member_ids(
+    user_group: UserGroup, *, direct_member_only: bool = False
+) -> List[int]:
+    if direct_member_only:
+        member_ids = get_user_group_direct_members(user_group)
+    else:
+        member_ids = get_recursive_group_members(user_group).values_list("id", flat=True)
+
+    return list(member_ids)
+
+
 def create_system_user_groups_for_realm(realm: Realm) -> Dict[int, UserGroup]:
     """Any changes to this function likely require a migration to adjust
     existing realms.  See e.g. migration 0375_create_role_based_system_groups.py,

zerver/openapi/zulip.yaml

@@ -13756,6 +13756,40 @@ paths:
       responses:
         "200":
           $ref: "#/components/responses/SimpleSuccess"
+    get:
+      operationId: get-user-group-members
+      summary: Get user group members
+      tags: ["users"]
+      description: |
+        Get the members of a [user group](/help/user-groups).
+
+        `GET {{ api_url }}/v1/user_groups/{user_group_id}/members`
+
+        **Changes**: New in Zulip 6.0 (feature level 127).
+      parameters:
+        - $ref: "#/components/parameters/UserGroupId"
+        - $ref: "#/components/parameters/DirectMemberOnly"
+      responses:
+        "200":
+          description: Success
+          content:
+            application/json:
+              schema:
+                allOf:
+                  - $ref: "#/components/schemas/JsonSuccessBase"
+                  - $ref: "#/components/schemas/SuccessDescription"
+                  - additionalProperties: false
+                    properties:
+                      result: {}
+                      msg: {}
+                      members:
+                        type: array
+                        items:
+                          type: integer
+                        description: |
+                          A list containing the user IDs of members of the user group.
+                    example:
+                      {"msg": "", "result": "success", "members": [10, 12]}
   /user_groups/{user_group_id}:
     patch:
       operationId: update-user-group

zerver/tests/test_user_groups.py

@@ -941,3 +941,41 @@ class UserGroupAPITestCase(UserGroupTestCase):
             self.client_get(f"/json/user_groups/{admins_group.id}/members/{othello.id}").content
         )
         self.assertFalse(result_dict["is_user_group_member"])
+
+    def test_get_user_group_members(self) -> None:
+        realm = get_realm("zulip")
+        iago = self.example_user("iago")
+        desdemona = self.example_user("desdemona")
+        shiva = self.example_user("shiva")
+        moderators_group = UserGroup.objects.get(
+            name="@role:moderators", realm=realm, is_system_group=True
+        )
+        self.login("iago")
+
+        # Test invalid user group id
+        result = self.client_get("/json/user_groups/25/members")
+        self.assert_json_error(result, "Invalid user group")
+
+        result_dict = orjson.loads(
+            self.client_get(f"/json/user_groups/{moderators_group.id}/members").content
+        )
+        self.assertCountEqual(result_dict["members"], [desdemona.id, iago.id, shiva.id])
+
+        params = {"direct_member_only": orjson.dumps(True).decode()}
+        result_dict = orjson.loads(
+            self.client_get(f"/json/user_groups/{moderators_group.id}/members", info=params).content
+        )
+        self.assertCountEqual(result_dict["members"], [shiva.id])
+
+        # User not part of a group can also get its members.
+        self.login("hamlet")
+        result_dict = orjson.loads(
+            self.client_get(f"/json/user_groups/{moderators_group.id}/members").content
+        )
+        self.assertCountEqual(result_dict["members"], [desdemona.id, iago.id, shiva.id])
+
+        params = {"direct_member_only": orjson.dumps(True).decode()}
+        result_dict = orjson.loads(
+            self.client_get(f"/json/user_groups/{moderators_group.id}/members", info=params).content
+        )
+        self.assertCountEqual(result_dict["members"], [shiva.id])

zerver/views/user_groups.py

@@ -22,6 +22,7 @@ from zerver.lib.user_groups import (
     access_user_groups_as_potential_subgroups,
     get_direct_memberships_of_users,
     get_user_group_direct_members,
+    get_user_group_member_ids,
     is_user_in_group,
     user_groups_in_realm_serialized,
 )
@@ -240,3 +241,21 @@ def get_is_user_group_member(
             )
         },
     )
+
+
+@require_member_or_admin
+@has_request_variables
+def get_user_group_members(
+    request: HttpRequest,
+    user_profile: UserProfile,
+    user_group_id: int = REQ(json_validator=check_int, path_only=True),
+    direct_member_only: bool = REQ(json_validator=check_bool, default=False),
+) -> HttpResponse:
+    user_group = access_user_group_by_id(user_group_id, user_profile, for_read=True)
+
+    return json_success(
+        request,
+        data={
+            "members": get_user_group_member_ids(user_group, direct_member_only=direct_member_only)
+        },
+    )

zproject/urls.py

@@ -178,6 +178,7 @@ from zerver.views.user_groups import (
     edit_user_group,
     get_is_user_group_member,
     get_user_group,
+    get_user_group_members,
     update_subgroups_of_user_group,
     update_user_group_backend,
 )
@@ -373,7 +374,11 @@ v1_api_and_json_patterns = [
     rest_path("user_groups", GET=get_user_group),
     rest_path("user_groups/create", POST=add_user_group),
     rest_path("user_groups/<int:user_group_id>", PATCH=edit_user_group, DELETE=delete_user_group),
-    rest_path("user_groups/<int:user_group_id>/members", POST=update_user_group_backend),
+    rest_path(
+        "user_groups/<int:user_group_id>/members",
+        GET=get_user_group_members,
+        POST=update_user_group_backend,
+    ),
     rest_path("user_groups/<int:user_group_id>/subgroups", POST=update_subgroups_of_user_group),
     rest_path(
         "user_groups/<int:user_group_id>/members/<int:user_id>", GET=get_is_user_group_member