Merge pull request #44000 from ykpythemind/better_message_for_missing

Better error messages when association name is invalid in the argument of `ActiveRecord::QueryMethods::WhereChain#missing`

activerecord/lib/active_record/relation/query_methods.rb

@@ -97,6 +97,9 @@ module ActiveRecord
       def missing(*associations)
         associations.each do |association|
           reflection = @scope.klass._reflect_on_association(association)
+          unless reflection
+            raise ArgumentError.new("An association named `:#{association}` does not exist on the model `#{@scope.name}`.")
+          end
           @scope.left_outer_joins!(association)
           @scope.where!(reflection.table_name => { reflection.association_primary_key => nil })
         end

activerecord/test/cases/relation/where_chain_test.rb

@@ -33,6 +33,14 @@ module ActiveRecord
       assert_equal [posts(:authorless)], Post.where.missing(:author).to_a
     end
 
+    def test_missing_with_invalid_association_name
+      e = assert_raises(ArgumentError) do
+        Post.where.missing(:cars).to_a
+      end
+
+      assert_match(/An association named `:cars` does not exist on the model `Post`\./, e.message)
+    end
+
     def test_missing_with_multiple_association
       assert posts(:authorless).comments.empty?
       assert_equal [posts(:authorless)], Post.where.missing(:author, :comments).to_a