Expose IDs in GraphQL as a GlobalID

This exposes all fields named `id` as GlobalIDs so they can be used
across our entire GraphQL implementation.

When the objects loaded are `ApplicationRecord`s. We'll use our
existing batchloading to find them. Otherwise, we'll fall back to the
default implementation of `GlobalID`: Calling the `.find` method on
the class.

5 files changed, 73 insertions, 4 deletions

diff --git a/spec/graphql/features/authorization_spec.rb b/spec/graphql/features/authorization_spec.rb
index f5eb628a982..c427893f9cc 100644
--- a/spec/graphql/features/authorization_spec.rb
+++ b/spec/graphql/features/authorization_spec.rb
@@ -282,7 +282,7 @@ describe 'Gitlab::Graphql::Authorization' do
       issue_ids = issue_edges.map { |issue_edge| issue_edge['node']&.fetch('id') }
 
       expect(issue_edges.size).to eq(visible_issues.size)
-      expect(issue_ids).to eq(visible_issues.map { |i| i.id.to_s })
+      expect(issue_ids).to eq(visible_issues.map { |i| i.to_global_id.to_s })
     end
 
     it 'does not check access on fields that will not be rendered' do
diff --git a/spec/graphql/gitlab_schema_spec.rb b/spec/graphql/gitlab_schema_spec.rb
index e9149f4250f..4076c1f824b 100644
--- a/spec/graphql/gitlab_schema_spec.rb
+++ b/spec/graphql/gitlab_schema_spec.rb
@@ -107,6 +107,64 @@ describe GitlabSchema do
     end
   end
 
+  describe '.id_from_object' do
+    it 'returns a global id' do
+      expect(described_class.id_from_object(build(:project, id: 1))).to be_a(GlobalID)
+    end
+
+    it "raises a meaningful error if a global id couldn't be generated" do
+      expect { described_class.id_from_object(build(:commit)) }
+        .to raise_error(RuntimeError, /include `GlobalID::Identification` into/i)
+    end
+  end
+
+  describe '.object_from_id' do
+    context 'for subclasses of `ApplicationRecord`' do
+      it 'returns the correct record' do
+        user = create(:user)
+
+        result = described_class.object_from_id(user.to_global_id.to_s)
+
+        expect(result.__sync).to eq(user)
+      end
+
+      it 'batchloads the queries' do
+        user1 = create(:user)
+        user2 = create(:user)
+
+        expect do
+          [described_class.object_from_id(user1.to_global_id),
+           described_class.object_from_id(user2.to_global_id)].map(&:__sync)
+        end.not_to exceed_query_limit(1)
+      end
+    end
+
+    context 'for other classes' do
+      # We cannot use an anonymous class here as `GlobalID` expects `.name` not
+      # to return `nil`
+      class TestGlobalId
+        include GlobalID::Identification
+        attr_accessor :id
+
+        def initialize(id)
+          @id = id
+        end
+      end
+
+      it 'falls back to a regular find' do
+        result = TestGlobalId.new(123)
+
+        expect(TestGlobalId).to receive(:find).with("123").and_return(result)
+
+        expect(described_class.object_from_id(result.to_global_id)).to eq(result)
+      end
+    end
+
+    it 'raises the correct error on invalid input' do
+      expect { described_class.object_from_id("bogus id") }.to raise_error(Gitlab::Graphql::Errors::ArgumentError)
+    end
+  end
+
   def field_instrumenters
     described_class.instrumenters[:field] + described_class.instrumenters[:field_after_built_ins]
   end
diff --git a/spec/requests/api/graphql/gitlab_schema_spec.rb b/spec/requests/api/graphql/gitlab_schema_spec.rb
index b6ca9246399..28676bb02f4 100644
--- a/spec/requests/api/graphql/gitlab_schema_spec.rb
+++ b/spec/requests/api/graphql/gitlab_schema_spec.rb
@@ -3,7 +3,7 @@ require 'spec_helper'
 describe 'GitlabSchema configurations' do
   include GraphqlHelpers
 
-  let(:project) { create(:project) }
+  set(:project) { create(:project) }
 
   shared_examples 'imposing query limits' do
     describe '#max_complexity' do
@@ -136,4 +136,15 @@ describe 'GitlabSchema configurations' do
       post_graphql(query, current_user: nil)
     end
   end
+
+  context "global id's" do
+    it 'uses GlobalID to expose ids' do
+      post_graphql(graphql_query_for('project', { 'fullPath' => project.full_path }, %w(id)),
+                   current_user: project.owner)
+
+      parsed_id = GlobalID.parse(graphql_data['project']['id'])
+
+      expect(parsed_id).to eq(project.to_global_id)
+    end
+  end
 end
diff --git a/spec/requests/api/graphql/group_query_spec.rb b/spec/requests/api/graphql/group_query_spec.rb
index db9f2ac9dd0..e0f1e4dbe9e 100644
--- a/spec/requests/api/graphql/group_query_spec.rb
+++ b/spec/requests/api/graphql/group_query_spec.rb
@@ -56,7 +56,7 @@ describe 'getting group information' do
         post_graphql(group_query(group1), current_user: user1)
 
         expect(response).to have_gitlab_http_status(200)
-        expect(graphql_data['group']['id']).to eq(group1.id.to_s)
+        expect(graphql_data['group']['id']).to eq(group1.to_global_id.to_s)
         expect(graphql_data['group']['name']).to eq(group1.name)
         expect(graphql_data['group']['path']).to eq(group1.path)
         expect(graphql_data['group']['description']).to eq(group1.description)
diff --git a/spec/requests/api/graphql/namespace/projects_spec.rb b/spec/requests/api/graphql/namespace/projects_spec.rb
index e05273da4bd..de1cd9586b6 100644
--- a/spec/requests/api/graphql/namespace/projects_spec.rb
+++ b/spec/requests/api/graphql/namespace/projects_spec.rb
@@ -60,7 +60,7 @@ describe 'getting projects', :nested_groups do
 
         expect(graphql_data['namespace']['projects']['edges'].size).to eq(1)
         project = graphql_data['namespace']['projects']['edges'][0]['node']
-        expect(project['id']).to eq(public_project.id.to_s)
+        expect(project['id']).to eq(public_project.to_global_id.to_s)
       end
     end
   end