Fix some issues when looking up aliased tables

The lookup for whether or not a column is an array fails in certain
cases when using aliased tables.  This fixes that issues.

Author: pnomolos

Gemfile

@@ -3,10 +3,6 @@ source 'https://rubygems.org'
 # Specify your gem's dependencies in postgres_ext.gemspec
 gemspec
 unless ENV['CI']
-  if RUBY_PLATFORM =~ /java/
-    gem 'ruby-debug'
-  else
-    gem 'byebug'
-  end
+  gem 'byebug'
 end
 gem 'fivemat'

lib/postgres_ext/active_record/relation/predicate_builder.rb

@@ -5,28 +5,34 @@ class PredicateBuilder # :nodoc:
     def self.build(attribute, value)
       case value
       when Array
-        engine = attribute.relation.engine
-        column = engine.connection.schema_cache.columns(attribute.relation.name).detect{ |col| col.name.to_s == attribute.name.to_s }
+        column = case attribute.try(:relation)
+                 when Arel::Nodes::TableAlias, NilClass
+                 else
+                   cache = attribute.relation.engine.connection.schema_cache
+                   if cache.table_exists? attribute.relation.name
+                     cache.columns(attribute.relation.name).detect{ |col| col.name.to_s == attribute.name.to_s } 
+                   end
+                 end
         if column && column.respond_to?(:array) && column.array
           attribute.eq(value)
         else
           values = value.to_a.map {|x| x.is_a?(Base) ? x.id : x}
           ranges, values = values.partition {|v| v.is_a?(Range)}
 
           values_predicate = if values.include?(nil)
-            values = values.compact
+                               values = values.compact
 
-            case values.length
-            when 0
-              attribute.eq(nil)
-            when 1
-              attribute.eq(values.first).or(attribute.eq(nil))
-            else
-              attribute.in(values).or(attribute.eq(nil))
-            end
-          else
-            attribute.in(values)
-          end
+                               case values.length
+                               when 0
+                                 attribute.eq(nil)
+                               when 1
+                                 attribute.eq(values.first).or(attribute.eq(nil))
+                               else
+                                 attribute.in(values).or(attribute.eq(nil))
+                               end
+                             else
+                               attribute.in(values)
+                             end
 
           array_predicates = ranges.map { |range| attribute.in(range) }
           array_predicates << values_predicate

lib/postgres_ext/active_record/relation/predicate_builder/array_handler.rb

@@ -10,8 +10,14 @@ module ArrayHandlerPatch
 
       included do
         def call_with_feature(attribute, value)
-          engine = attribute.relation.engine
-          column = engine.connection.schema_cache.columns(attribute.relation.name).detect{ |col| col.name.to_s == attribute.name.to_s }
+          column = case attribute.try(:relation)
+                   when Arel::Nodes::TableAlias, NilClass
+                   else
+                     cache = attribute.relation.engine.connection.schema_cache
+                     if cache.table_exists? attribute.relation.name
+                       cache.columns(attribute.relation.name).detect{ |col| col.name.to_s == attribute.name.to_s }
+                     end
+                   end
           if column && column.respond_to?(:array) && column.array
             attribute.eq(value)
           else

lib/postgres_ext/arel/4.1/visitors/postgresql.rb

@@ -12,10 +12,12 @@ def visit_Array o, a
                  # which won't exist for aliased table when used with Single Table
                  # Inheritance. see dockyard/postgres_ext#154
                  else
-                   a.relation.engine.connection.schema_cache.columns(a.relation.name)
-                     .find { |col| col.name == a.name.to_s }
+                  cache = a.relation.engine.connection.schema_cache
+                  if cache.table_exists? a.relation.name
+                    cache.columns(a.relation.name).find { |col| col.name == a.name.to_s }
+                  end
                  end
-        
+
         if column && column.respond_to?(:array) && column.array
           quoted o, a
         else
@@ -25,14 +27,14 @@ def visit_Array o, a
 
       def visit_Arel_Nodes_Contains o, a = nil
         left_column = o.left.relation.engine.columns.find { |col| col.name == o.left.name.to_s }
-        
+
         if left_column && (left_column.type == :hstore || (left_column.respond_to?(:array) && left_column.array))
           "#{visit o.left, a} @> #{visit o.right, o.left}"
         else
           "#{visit o.left, a} >> #{visit o.right, o.left}"
         end
       end
-      
+
       def visit_Arel_Nodes_ContainedWithin o, a = nil
         "#{visit o.left, a} << #{visit o.right, o.left}"
       end

test/queries/alias_test.rb

@@ -0,0 +1,8 @@
+require 'test_helper'
+
+describe 'Joining with an alias' do
+  it "Works properly" do
+    ChildTag.includes(:parent_tag).references(:parent_tag)
+      .where("parent_tags_tags.id" => [2,3,4]).to_sql.must_match /"parent_tags_tags"."id" IN \(2, 3, 4\)/
+  end
+end