Merge branch 'api-filter-milestone' into 'master'

API: Ability to filter milestones by state

Ability to filter milestones by `active` and `closed` state.

* Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/14931

See merge request !3566

4 files changed, 54 insertions, 6 deletions

diff --git a/CHANGELOG b/CHANGELOG
index 105346a1f40..2f19f259833 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -18,6 +18,7 @@ v 8.7.0 (unreleased)
   - Handle nil descriptions in Slack issue messages (Stan Hu)
   - Add default scope to projects to exclude projects pending deletion
   - Ensure empty recipients are rejected in BuildsEmailService
+  - API: Ability to filter milestones by state `active` and `closed` (Robert Schilling)
   - Implement 'Groups View' as an option for dashboard preferences !3379 (Elias W.)
   - Implement 'TODOs View' as an option for dashboard preferences !3379 (Elias W.)
   - Gracefully handle notes on deleted commits in merge requests (Stan Hu)
diff --git a/doc/api/milestones.md b/doc/api/milestones.md
index a6828728264..e4202025f80 100644
--- a/doc/api/milestones.md
+++ b/doc/api/milestones.md
@@ -7,8 +7,24 @@ Returns a list of project milestones.
 ```
 GET /projects/:id/milestones
 GET /projects/:id/milestones?iid=42
+GET /projects/:id/milestones?state=active
+GET /projects/:id/milestones?state=closed
 ```
 
+Parameters:
+
+| Attribute | Type | Required | Description |
+| --------- | ---- | -------- | ----------- |
+| `id` | integer | yes | The ID of a project |
+| `iid` | integer | optional | Return only the milestone having the given `iid` |
+| `state` | string | optional | Return  only `active` or `closed` milestones` |
+
+```bash
+curl -H "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" https://gitlab.example.com/api/v3/projects/5/milestones
+```
+
+Example Response:
+
 ```json
 [
   {
@@ -25,10 +41,6 @@ GET /projects/:id/milestones?iid=42
 ]
 ```
 
-Parameters:
-
-- `id` (required) - The ID of a project
-- `iid` (optional) - Return the milestone having the given `iid`
 
 ## Get single milestone
 
diff --git a/lib/api/milestones.rb b/lib/api/milestones.rb
index c5cd73943fb..afb6ffa3609 100644
--- a/lib/api/milestones.rb
+++ b/lib/api/milestones.rb
@@ -3,17 +3,33 @@ module API
   class Milestones < Grape::API
     before { authenticate! }
 
+    helpers do
+      def filter_milestones_state(milestones, state)
+        case state
+        when 'active' then milestones.active
+        when 'closed' then milestones.closed
+        else milestones
+        end
+      end
+    end
+
     resource :projects do
       # Get a list of project milestones
       #
       # Parameters:
-      #   id (required) - The ID of a project
+      #   id (required)    - The ID of a project
+      #   state (optional) - Return "active" or "closed" milestones
       # Example Request:
       #   GET /projects/:id/milestones
+      #   GET /projects/:id/milestones?state=active
+      #   GET /projects/:id/milestones?state=closed
       get ":id/milestones" do
         authorize! :read_milestone, user_project
 
-        present paginate(user_project.milestones), with: Entities::Milestone
+        milestones = user_project.milestones
+        milestones = filter_milestones_state(milestones, params[:state])
+
+        present paginate(milestones), with: Entities::Milestone
       end
 
       # Get a single project milestone
diff --git a/spec/requests/api/milestones_spec.rb b/spec/requests/api/milestones_spec.rb
index db0f6e3c0f5..d97bf6d38ff 100644
--- a/spec/requests/api/milestones_spec.rb
+++ b/spec/requests/api/milestones_spec.rb
@@ -4,6 +4,7 @@ describe API::API, api: true  do
   include ApiHelpers
   let(:user) { create(:user) }
   let!(:project) { create(:project, namespace: user.namespace ) }
+  let!(:closed_milestone) { create(:closed_milestone, project: project) }
   let!(:milestone) { create(:milestone, project: project) }
 
   before { project.team << [user, :developer] }
@@ -20,6 +21,24 @@ describe API::API, api: true  do
       get api("/projects/#{project.id}/milestones")
       expect(response.status).to eq(401)
     end
+
+    it 'returns an array of active milestones' do
+      get api("/projects/#{project.id}/milestones?state=active", user)
+
+      expect(response.status).to eq(200)
+      expect(json_response).to be_an Array
+      expect(json_response.length).to eq(1)
+      expect(json_response.first['id']).to eq(milestone.id)
+    end
+
+    it 'returns an array of closed milestones' do
+      get api("/projects/#{project.id}/milestones?state=closed", user)
+
+      expect(response.status).to eq(200)
+      expect(json_response).to be_an Array
+      expect(json_response.length).to eq(1)
+      expect(json_response.first['id']).to eq(closed_milestone.id)
+    end
   end
 
   describe 'GET /projects/:id/milestones/:milestone_id' do