Implement multiple variable handling action

app/controllers/projects/variables_controller.rb

@@ -33,8 +33,21 @@ class Projects::VariablesController < Projects::ApplicationController
   end
 
   def save_multiple
+    respond_to do |format|
+      format.json do
+        variables = []
+        variables_params[:variables].each do |variable_hash|
+          variable = project.variables.where(key: variable_hash[:key]).first_or_initialize(variable_hash)
+          variable.assign_attributes(variable_hash) unless variable.new_record?
+          return head :bad_request unless variable.valid?
+
+          variables << variable
+        end
+        variables.each { |variable| variable.save }
+      end
       head :ok
     end
+  end
 
   def destroy
     if variable.destroy
@@ -54,6 +67,10 @@ class Projects::VariablesController < Projects::ApplicationController
     params.require(:variable).permit(*variable_params_attributes)
   end
 
+  def variables_params
+    params.permit(variables: [*variable_params_attributes])
+  end
+
   def variable_params_attributes
     %i[id key value protected _destroy]
   end

spec/controllers/projects/variables_controller_spec.rb

@@ -57,9 +57,58 @@ describe Projects::VariablesController do
   end
 
   describe 'POST #save_multiple' do
+    let(:variable) { create(:ci_variable) }
+
+    before do
+      project.variables << variable
+    end
+
+    context 'with invalid new variable parameters' do
+      subject do
+        post :save_multiple,
+          namespace_id: project.namespace.to_param, project_id: project,
+          variables: [{ key: variable.key, value: 'other_value' },
+                      { key: '..?', value: 'dummy_value' }],
+          format: :json
+      end
+
+      it 'does not update the existing variable' do
+        expect { subject }.not_to change { variable.reload.value }
+      end
+
+      it 'does not create the new variable' do
+        expect { subject }.not_to change { project.variables.count }
+      end
+
+      it 'returns a bad request response' do
+        subject
+
+        expect(response).to have_gitlab_http_status(:bad_request)
+      end
+    end
+
+    context 'with valid new variable parameters' do
+      subject do
+        post :save_multiple,
+          namespace_id: project.namespace.to_param, project_id: project,
+          variables: [{ key: variable.key, value: 'other_value' },
+                      { key: 'new_key', value: 'dummy_value' }],
+          format: :json
+      end
+
+      it 'updates the existing variable' do
+        expect { subject }.to change { variable.reload.value }.to('other_value')
+      end
+
+      it 'creates the new variable' do
+        expect { subject }.to change { project.variables.count }.by(1)
+      end
+
       it 'returns a successful response' do
-      post :save_multiple, namespace_id: project.namespace.to_param, project_id: project
+        subject
+
         expect(response).to have_gitlab_http_status(:ok)
       end
     end
+  end
 end