Merge branch '42415-omit-projects-from-get-group-endpoint' into 'master'

Resolve "API: /groups/:name query very slow for groups with many projects"

Closes #42415

See merge request gitlab-org/gitlab-ce!20494

changelogs/unreleased/42415-omit-projects-from-get-group-endpoint.yml

+---
+title: Adds with_projects optional parameter to GET /groups/:id API endpoint
+merge_request: 20494
+author:
+type: changed

doc/api/groups.md

@@ -210,6 +210,7 @@ Parameters:
 | --------- | ---- | -------- | ----------- |
 | `id` | integer/string | yes | The ID or [URL-encoded path of the group](README.md#namespaced-path-encoding) owned by the authenticated user |
 | `with_custom_attributes` | boolean | no | Include [custom attributes](custom_attributes.md) in response (admins only) |
+| `with_projects` | boolean | no | Include details from projects that belong to the specified group (defaults to `true`). |
 ```bash
 curl --header "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" https://gitlab.example.com/api/v4/groups/4
@@ -361,6 +362,30 @@ Example response:
 }
 ```
+When adding the parameter `with_projects=false`, projects will not be returned.
+
+```bash
+curl --header "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" https://gitlab.example.com/api/v4/groups/4?with_projects=false
+```
+
+Example response:
+
+```json
+{
+  "id": 4,
+  "name": "Twitter",
+  "path": "twitter",
+  "description": "Aliquid qui quis dignissimos distinctio ut commodi voluptas est.",
+  "visibility": "public",
+  "avatar_url": null,
+  "web_url": "https://gitlab.example.com/groups/twitter",
+  "request_access_enabled": false,
+  "full_name": "Twitter",
+  "full_path": "twitter",
+  "parent_id": null
+}
+```
+
 ## New group
 Creates a new project group. Available only for users who can create groups.

lib/api/groups.rb

@@ -150,12 +150,13 @@ module API
       end
       params do
         use :with_custom_attributes
+        optional :with_projects, type: Boolean, default: true, desc: 'Omit project details'
       end
       get ":id" do
         group = find_group!(params[:id])
         options = {
-          with: Entities::GroupDetail,
+          with: params[:with_projects] ? Entities::GroupDetail : Entities::Group,
           current_user: current_user
         }

spec/requests/api/groups_spec.rb

@@ -251,14 +251,22 @@ describe API::Groups do
       projects
     end
+    def response_project_ids(json_response, key)
+      json_response[key].map do |project|
+        project['id'].to_i
+      end
+    end
+
     context 'when unauthenticated' do
       it 'returns 404 for a private group' do
         get api("/groups/#{group2.id}")
+
         expect(response).to have_gitlab_http_status(404)
       end
       it 'returns 200 for a public group' do
         get api("/groups/#{group1.id}")
+
         expect(response).to have_gitlab_http_status(200)
       end
@@ -268,7 +276,7 @@ describe API::Groups do
         get api("/groups/#{public_group.id}")
-        expect(json_response['projects'].map { |p| p['id'].to_i })
+        expect(response_project_ids(json_response, 'projects'))
           .to contain_exactly(projects[:public].id)
       end
@@ -278,7 +286,7 @@ describe API::Groups do
         get api("/groups/#{group1.id}")
-        expect(json_response['shared_projects'].map { |p| p['id'].to_i })
+        expect(response_project_ids(json_response, 'shared_projects'))
           .to contain_exactly(projects[:public].id)
       end
     end
@@ -309,6 +317,17 @@ describe API::Groups do
         expect(json_response['shared_projects'][0]['id']).to eq(project.id)
       end
+      it "returns one of user1's groups without projects when with_projects option is set to false" do
+        project = create(:project, namespace: group2, path: 'Foo')
+        create(:project_group_link, project: project, group: group1)
+
+        get api("/groups/#{group1.id}", user1), with_projects: false
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(json_response['projects']).to be_nil
+        expect(json_response['shared_projects']).to be_nil
+      end
+
       it "does not return a non existing group" do
         get api("/groups/1328", user1)
@@ -327,7 +346,7 @@ describe API::Groups do
         get api("/groups/#{public_group.id}", user2)
-        expect(json_response['projects'].map { |p| p['id'].to_i })
+        expect(response_project_ids(json_response, 'projects'))
           .to contain_exactly(projects[:public].id, projects[:internal].id)
       end
@@ -337,7 +356,7 @@ describe API::Groups do
         get api("/groups/#{group1.id}", user2)
-        expect(json_response['shared_projects'].map { |p| p['id'].to_i })
+        expect(response_project_ids(json_response, 'shared_projects'))
           .to contain_exactly(projects[:public].id, projects[:internal].id)
       end
     end