Merge pull request #17473 from NickLaMuro/virtual_delegate_has_one_sc…

…ope_support Add has_one scope support to virtual_delegate
ManageIQ · Jun 11, 2018 · 0ce8fb4 · 0ce8fb4
2 parents b2ba3ff + fec164a
commit 0ce8fb4
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Showing 2 changed files with 35 additions and 4 deletions.
diff --git a/lib/extensions/ar_virtual.rb b/lib/extensions/ar_virtual.rb
@@ -198,7 +198,9 @@ def virtual_delegate_arel(col, to_ref)
         if to_ref.macro == :has_one
           lambda do |t|
             src_model_id = arel_attribute(to_ref.association_primary_key, t)
-            VirtualDelegates.select_from_alias(to_ref, col, to_ref.foreign_key, src_model_id)
+            VirtualDelegates.select_from_alias(to_ref, col, to_ref.foreign_key, src_model_id) do |arel|
+              arel.limit = 1
+            end
           end
         elsif to_ref.macro == :belongs_to
           lambda do |t|
@@ -287,10 +289,22 @@ def virtual_delegate_arel(col, to_ref)
   #
 
   def self.select_from_alias(to_ref, col, to_model_col_name, src_model_id)
-    to_table = select_from_alias_table(to_ref.klass, src_model_id.relation)
+    query = if to_ref.scope
+              to_ref.klass.instance_exec(nil, &to_ref.scope)
+            else
+              to_ref.klass.all
+            end
+
+    to_table    = select_from_alias_table(to_ref.klass, src_model_id.relation)
     to_model_id = to_ref.klass.arel_attribute(to_model_col_name, to_table)
-    to_column = to_ref.klass.arel_attribute(col, to_table)
-    Arel.sql("(#{to_table.project(to_column).where(to_model_id.eq(src_model_id)).to_sql})")
+    to_column   = to_ref.klass.arel_attribute(col, to_table)
+    arel        = query.select(to_column).arel
+                       .from(to_table)
+                       .where(to_model_id.eq(src_model_id))
+
+    yield arel if block_given?
+
+    Arel.sql("(#{arel.to_sql})")
   end
 
   # determine table reference to use for a sub query

diff --git a/spec/lib/extensions/ar_virtual_spec.rb b/spec/lib/extensions/ar_virtual_spec.rb
@@ -622,11 +622,19 @@ def self.connection
 
             include VirtualFields
           end
+
+          class CompSys < ComputerSystem
+            has_one :first_os, -> { order(:name) },
+                    :class_name  => "OperatingSystem",
+                    :foreign_key => "computer_system_id",
+                    :dependent   => :destroy
+          end
         end
 
         after do
           TestOtherClass.remove_connection
           Object.send(:remove_const, :TestOtherClass)
+          Object.send(:remove_const, :CompSys)
         end
 
         it "delegates to another table" do
@@ -644,6 +652,15 @@ def self.connection
           sql = TestOtherClass.all.select(:id, :ocol1, TestOtherClass.arel_attribute(:col1).as("x")).to_sql
           expect(sql).to match(/"test_classes"."col1"/i)
         end
+
+        it "delegates has_one relationships with limit 1" do
+          CompSys.virtual_delegate :first_os_name, :to => 'first_os.name'
+          comp_sys = CompSys.create!
+          OperatingSystem.create(:name => "foo", :computer_system_id => comp_sys.id)
+          OperatingSystem.create(:name => "bar", :computer_system_id => comp_sys.id)
+          query = CompSys.all.select(:id, :first_os_name)
+          expect(query.map(&:first_os_name)).to match_array(["bar"])
+        end
       end
     end