Merge pull request #7380 from ernie/fix-nomethoderror-on-non-attribute-equalities

Fix merge error when Equality LHS is non-attribute

1 files changed, 5 insertions, 2 deletions

diff --git a/activerecord/lib/active_record/relation/merger.rb b/activerecord/lib/active_record/relation/merger.rb
index 71aaedee1e..7531f22494 100644
--- a/activerecord/lib/active_record/relation/merger.rb
+++ b/activerecord/lib/active_record/relation/merger.rb
@@ -97,11 +97,14 @@ module ActiveRecord
           merged_wheres = relation.where_values + values[:where]
 
           unless relation.where_values.empty?
-            # Remove duplicates, last one wins.
+            # Remove duplicate ARel attributes. Last one wins.
             seen = Hash.new { |h,table| h[table] = {} }
             merged_wheres = merged_wheres.reverse.reject { |w|
               nuke = false
-              if w.respond_to?(:operator) && w.operator == :==
+              # We might have non-attributes on the left side of equality nodes,
+              # so we need to make sure they quack like an attribute.
+              if w.respond_to?(:operator) && w.operator == :== &&
+                w.left.respond_to?(:relation)
                 name              = w.left.name
                 table             = w.left.relation.name
                 nuke              = seen[table][name]