Set author as nullable in snippet GraphQL Type

app/graphql/types/snippet_type.rb

@@ -27,9 +27,12 @@ module Types
           authorize: :read_project,
           resolve: -> (snippet, args, context) { Gitlab::Graphql::Loaders::BatchModelLoader.new(Project, snippet.project_id).find }
 
+    # Author can be nil in some scenarios. For example,
+    # when the admin setting restricted visibility
+    # level is set to public
     field :author, Types::UserType,
           description: 'The owner of the snippet',
-          null: false,
+          null: true,
           resolve: -> (snippet, args, context) { Gitlab::Graphql::Loaders::BatchModelLoader.new(User, snippet.author_id).find }
 
     field :file_name, GraphQL::STRING_TYPE,

changelogs/unreleased/fj-change-snippet-author-nullable-graphql-type.yml

+---
+title: Set author as nullable in snippet GraphQL Type
+merge_request: 34135
+author:
+type: fixed

doc/api/graphql/reference/gitlab_schema.graphql

@@ -11155,7 +11155,7 @@ type Snippet implements Noteable {
   """
   The owner of the snippet
   """
-  author: User!
+  author: User
 
   """
   Snippet blob

doc/api/graphql/reference/gitlab_schema.json

@@ -32945,13 +32945,9 @@
 
               ],
               "type": {
-                "kind": "NON_NULL",
-                "name": null,
-                "ofType": {
-                  "kind": "OBJECT",
-                  "name": "User",
-                  "ofType": null
-                }
+                "kind": "OBJECT",
+                "name": "User",
+                "ofType": null
               },
               "isDeprecated": false,
               "deprecationReason": null

doc/api/graphql/reference/index.md

@@ -1630,7 +1630,7 @@ Represents a snippet entry
 
 | Name  | Type  | Description |
 | ---   |  ---- | ----------  |
-| `author` | User! | The owner of the snippet |
+| `author` | User | The owner of the snippet |
 | `blob` | SnippetBlob! | Snippet blob |
 | `createdAt` | Time! | Timestamp this snippet was created |
 | `description` | String | Description of the snippet |

spec/graphql/types/snippet_type_spec.rb

@@ -16,6 +16,44 @@ describe GitlabSchema.types['Snippet'] do
     expect(described_class).to have_graphql_fields(*expected_fields)
   end
 
+  context 'when restricted visibility level is set to public' do
+    let_it_be(:snippet) { create(:personal_snippet, :repository, :public, author: user) }
+
+    let(:current_user) { user }
+    let(:query) do
+      %(
+        {
+          snippets {
+            nodes {
+              author {
+                id
+              }
+            }
+          }
+        }
+      )
+    end
+    let(:response) { subject.dig('data', 'snippets', 'nodes')[0] }
+
+    subject { GitlabSchema.execute(query, context: { current_user: current_user }).as_json }
+
+    before do
+      stub_application_setting(restricted_visibility_levels: [Gitlab::VisibilityLevel::PUBLIC])
+    end
+
+    it 'returns snippet author' do
+      expect(response['author']).to be_present
+    end
+
+    context 'when user is not logged in' do
+      let(:current_user) { nil }
+
+      it 'returns snippet author as nil' do
+        expect(response['author']).to be_nil
+      end
+    end
+  end
+
   describe 'authorizations' do
     specify { expect(described_class).to require_graphql_authorizations(:read_snippet) }
   end