add method to get a full routable hierarchy

app/models/concerns/routable.rb

@@ -83,6 +83,74 @@ module Routable
                AND members.source_type = r2.source_type").
         where('members.user_id = ?', user_id)
     end
+
+    # Builds a relation to find multiple objects that are nested under user
+    # membership. Includes the parent, as opposed to `#member_descendants`
+    # which only includes the descendants.
+    #
+    # Usage:
+    #
+    #     Klass.member_self_and_descendants(1)
+    #
+    # Returns an ActiveRecord::Relation.
+    def member_self_and_descendants(user_id)
+      joins(:route).
+        joins("INNER JOIN routes r2 ON routes.path LIKE CONCAT(r2.path, '/%')
+               OR routes.path = r2.path
+               INNER JOIN members ON members.source_id = r2.source_id
+               AND members.source_type = r2.source_type").
+        where('members.user_id = ?', user_id)
+    end
+
+    # Returns all objects in a hierarchy, where any node in the hierarchy is
+    # under the user membership.
+    #
+    # Usage:
+    #
+    #     Klass.member_hierarchy(1)
+    #
+    # Examples:
+    #
+    #     Given the following group tree...
+    #
+    #            _______group_1_______
+    #           |                     |
+    #           |                     |
+    #     nested_group_1        nested_group_2
+    #           |                     |
+    #           |                     |
+    #     nested_group_1_1      nested_group_2_1
+    #
+    #
+    #     ... the following results are returned:
+    #
+    #     * the user is a member of group 1
+    #       => 'group_1',
+    #          'nested_group_1', nested_group_1_1',
+    #          'nested_group_2', 'nested_group_2_1'
+    #
+    #     * the user is a member of nested_group_2
+    #       => 'group1',
+    #          'nested_group_2', 'nested_group_2_1'
+    #
+    #     * the user is a member of nested_group_2_1
+    #       => 'group1',
+    #          'nested_group_2', 'nested_group_2_1'
+    #
+    # Returns an ActiveRecord::Relation.
+    def member_hierarchy(user_id)
+      paths = member_self_and_descendants(user_id).pluck('routes.path')
+
+      return none if paths.empty?
+
+      leaf_paths = paths.group_by(&:length).flat_map(&:last)
+
+      wheres = leaf_paths.map do |leaf_path|
+        "#{connection.quote(leaf_path)} LIKE CONCAT(routes.path, '%')"
+      end
+
+      joins(:route).where(wheres.join(' OR '))
+    end
   end
 
   def full_name

spec/models/concerns/routable_spec.rb

 require 'spec_helper'
 
 describe Group, 'Routable' do
-  let!(:group) { create(:group) }
+  let!(:group) { create(:group, name: 'group 1') }
 
   describe 'Validations' do
     it { is_expected.to validate_presence_of(:route) }
@@ -81,6 +81,97 @@ describe Group, 'Routable' do
     it { is_expected.to eq([nested_group]) }
   end
 
+  describe '.member_self_and_descendants' do
+    let!(:user) { create(:user) }
+    let!(:nested_group) { create(:group, parent: group) }
+
+    before { group.add_owner(user) }
+    subject { described_class.member_self_and_descendants(user.id) }
+
+    it { is_expected.to match_array [group, nested_group] }
+  end
+
+  describe '.member_hierarchy' do
+    let!(:user) { create(:user) }
+
+    #        _______ group _______
+    #       |                     |
+    #       |                     |
+    # nested_group_1        nested_group_2
+    #       |                     |
+    #       |                     |
+    # nested_group_1_1      nested_group_2_1
+    #
+    let!(:nested_group_1) { create :group, parent: group, name: 'group 1-1' }
+    let!(:nested_group_1_1) { create :group, parent: nested_group_1, name: 'group 1-1-1' }
+    let!(:nested_group_2) { create :group, parent: group, name: 'group 1-2' }
+    let!(:nested_group_2_1) { create :group, parent: nested_group_2, name: 'group 1-2-1' }
+
+    context 'user is not a member of any group' do
+      subject { described_class.member_hierarchy(user.id) }
+
+      it 'returns an empty array' do
+        is_expected.to eq []
+      end
+    end
+
+    context 'user is member of all groups' do
+      before do
+        group.add_owner(user)
+        nested_group_1.add_owner(user)
+        nested_group_1_1.add_owner(user)
+        nested_group_2.add_owner(user)
+        nested_group_2_1.add_owner(user)
+      end
+      subject { described_class.member_hierarchy(user.id) }
+
+      it 'returns all groups' do
+        is_expected.to match_array [
+          group,
+          nested_group_1, nested_group_1_1,
+          nested_group_2, nested_group_2_1
+        ]
+      end
+    end
+
+    context 'user is member of the top group' do
+      before { group.add_owner(user) }
+      subject { described_class.member_hierarchy(user.id) }
+
+      it 'returns all groups' do
+        is_expected.to match_array [
+          group,
+          nested_group_1, nested_group_1_1,
+          nested_group_2, nested_group_2_1
+        ]
+      end
+    end
+
+    context 'user is member of the first child (internal node)' do
+      before { nested_group_1.add_owner(user) }
+      subject { described_class.member_hierarchy(user.id) }
+
+      it 'returns the groups in the hierarchy' do
+        is_expected.to match_array [
+          group,
+          nested_group_1, nested_group_1_1
+        ]
+      end
+    end
+
+    context 'user is member of the last child (leaf node)' do
+      before { nested_group_1_1.add_owner(user) }
+      subject { described_class.member_hierarchy(user.id) }
+
+      it 'returns the groups in the hierarchy' do
+        is_expected.to match_array [
+          group,
+          nested_group_1, nested_group_1_1
+        ]
+      end
+    end
+  end
+
   describe '#full_path' do
     let(:group) { create(:group) }
     let(:nested_group) { create(:group, parent: group) }