Add excluding tag to API

app/api/issue_api.rb

@@ -46,6 +46,7 @@ def bbox_from_string(string, factory)
     params do
       optional :bbox, type: String, desc: 'Four comma-separated coordinates making up the boundary of interest, e.g. "0.11905,52.20791,0.11907,52.20793"'
       optional :tags, type: Array, desc: 'An array of tags all the issues must have, e.g. ["taga","tagb"]', coerce_with: JSON
+      optional :excluding_tags, type: Array, desc: 'An array of tags that the issues must not have, e.g. ["taga","tagb"]', coerce_with: JSON
       optional :group, type: String, desc: 'Return only issues from area of group given by its short name, e.g. "london"'
       optional :order, type: String, desc: 'Order of returned issues. Current working parameters are: "vote_count", "created_at", "start_at", "size"'
       optional :end_date, type: Date, desc: 'No issues after the end date are returned'
@@ -69,6 +70,7 @@ def bbox_from_string(string, factory)
       end
       scope = scope.intersects_not_covered(bbox_from_string(params[:bbox], Issue.rgeo_factory).to_geometry) if params[:bbox].present?
       scope = scope.where_tag_names_in(params[:tags]) if params[:tags]
+      scope = scope.where_tag_names_not_in(params[:excluding_tags]) if params[:excluding_tags]
       scope = scope.before_date(params[:end_date]) if params[:end_date]
       scope = scope.after_date(params[:start_date]) if params[:start_date]
       scope = paginate scope

lib/taggable.rb

@@ -15,13 +15,26 @@ def find_by_tag(tag)
     end
 
     def where_tag_names_in(tag_names)
-      if tag_names.present? &&
-        ids = joins(:tags).where(tags: {name: tag_names}).group('issues.id').having('COUNT(tags.id)=?', tag_names.size)
-        where(id: ids)
+      if tag_names.present?
+        where(id: ids_with_all(tag_names))
       else
         none
       end
     end
+
+    def where_tag_names_not_in(tag_names)
+      if tag_names.present?
+        where.not(id: ids_with_all(tag_names))
+      else
+        all
+      end
+    end
+
+    private
+
+    def ids_with_all(tag_names)
+      joins(:tags).where(tags: {name: tag_names}).group('issues.id').having('COUNT(tags.id)=?', tag_names.size)
+    end
   end
 
   def tags_string

spec/models/issue_spec.rb

@@ -375,13 +375,21 @@
       end
     end
 
-    describe 'where_tag_names_in' do
-      it 'should return the issues which have all of the tags' do
-        tag1 = create :tag, name: 'tag1'
-        tag2 = create :tag, name: 'tag2'
-        tag3 = create :tag, name: 'tag3'
-        with_tags = create :issue, tags: [tag1, tag2]
-        with_other_tags = create :issue, tags: [tag1, tag3]
+    describe 'where_tag_names' do
+      let(:tag1) { create :tag, name: 'tag1' }
+      let(:tag2) { create :tag, name: 'tag2' }
+      let(:tag3) { create :tag, name: 'tag3' }
+      let!(:with_tags) { create :issue, tags: [tag1, tag2] }
+      let!(:with_other_tags) { create :issue, tags: [tag1, tag3] }
+
+      it 'not in should return the issues which do not have the tags' do
+        no_tag = create :issue
+        expect(described_class.all.where_tag_names_not_in([])).to match_array([no_tag, with_tags, with_other_tags])
+        expect(described_class.all.where_tag_names_not_in(['tag2'])).to match_array([no_tag, with_other_tags])
+        expect(described_class.all.where_tag_names_not_in(['tag1'])).to match_array([no_tag])
+      end
+
+      it 'in should return the issues which have all of the tags' do
         create :issue
 
         expect(described_class.where_tag_names_in(['tag1'])).to match_array([with_tags, with_other_tags])