Handle aliased attributes in ActiveRecord::Relation.

When using symbol keys, ActiveRecord will now translate aliased attribute names to the actual column name used in the database:

With the model

  class Topic
    alias_attribute :heading, :title
  end

The call

  Topic.where(heading: 'The First Topic')

should yield the same result as

  Topic.where(title: 'The First Topic')

This also applies to ActiveRecord::Relation::Calculations calls such as `Model.sum(:aliased)` and `Model.pluck(:aliased)`.

This will not work with SQL fragment strings like `Model.sum('DISTINCT aliased')`.

Github #7839

*Godfrey Chan*

activerecord/CHANGELOG.md

+*   Handle aliased attributes in ActiveRecord::Relation.
+
+    When using symbol keys, ActiveRecord will now translate aliased attribute names to the actual column name used in the database:
+
+    With the model
+
+        class Topic
+          alias_attribute :heading, :title
+        end
+
+    The call
+
+        Topic.where(heading: 'The First Topic')
+
+    should yield the same result as
+
+        Topic.where(title: 'The First Topic')
+
+    This also applies to ActiveRecord::Relation::Calculations calls such as `Model.sum(:aliased)` and `Model.pluck(:aliased)`.
+
+    This will not work with SQL fragment strings like `Model.sum('DISTINCT aliased')`.
+
+    *Godfrey Chan*
+
 *   Mute `psql` output when running rake db:schema:load.
 
     *Godfrey Chan*

activerecord/lib/active_record/relation/calculations.rb

@@ -27,7 +27,7 @@ def count(column_name = nil, options = {})
     # Calculates the average value on a given column. Returns +nil+ if there's
     # no row. See +calculate+ for examples with options.
     #
-    #   Person.average('age') # => 35.8
+    #   Person.average(:age) # => 35.8
     def average(column_name, options = {})
       calculate(:average, column_name, options)
     end
@@ -36,7 +36,7 @@ def average(column_name, options = {})
     # with the same data type of the column, or +nil+ if there's no row. See
     # +calculate+ for examples with options.
     #
-    #   Person.minimum('age') # => 7
+    #   Person.minimum(:age) # => 7
     def minimum(column_name, options = {})
       calculate(:minimum, column_name, options)
     end
@@ -45,7 +45,7 @@ def minimum(column_name, options = {})
     # with the same data type of the column, or +nil+ if there's no row. See
     # +calculate+ for examples with options.
     #
-    #   Person.maximum('age') # => 93
+    #   Person.maximum(:age) # => 93
     def maximum(column_name, options = {})
       calculate(:maximum, column_name, options)
     end
@@ -54,7 +54,7 @@ def maximum(column_name, options = {})
     # with the same data type of the column, 0 if there's no row. See
     # +calculate+ for examples with options.
     #
-    #   Person.sum('age') # => 4562
+    #   Person.sum(:age) # => 4562
     def sum(*args)
       if block_given?
         ActiveSupport::Deprecation.warn(
@@ -101,6 +101,10 @@ def sum(*args)
     def calculate(operation, column_name, options = {})
       relation = with_default_scope
 
+      if column_name.is_a?(Symbol) && attribute_aliases.key?(column_name.to_s)
+        column_name = attribute_aliases[column_name.to_s].to_sym
+      end
+
       if relation.equal?(self)
         if has_include?(column_name)
           construct_relation_for_association_calculations.calculate(operation, column_name, options)
@@ -149,11 +153,17 @@ def calculate(operation, column_name, options = {})
     #
     def pluck(*column_names)
       column_names.map! do |column_name|
-        if column_name.is_a?(Symbol) && self.column_names.include?(column_name.to_s)
-          "#{connection.quote_table_name(table_name)}.#{connection.quote_column_name(column_name)}"
-        else
-          column_name
+        if column_name.is_a?(Symbol)
+          if attribute_aliases.key?(column_name.to_s)
+            column_name = attribute_aliases[column_name.to_s].to_sym
+          end
+
+          if self.columns_hash.key?(column_name.to_s)
+            column_name = "#{connection.quote_table_name(table_name)}.#{connection.quote_column_name(column_name)}"
+          end
         end
+
+        column_name
       end
 
       if has_include?(column_names.first)

activerecord/lib/active_record/relation/predicate_builder.rb

@@ -6,6 +6,10 @@ def self.build_from_hash(klass, attributes, default_table)
       attributes.each do |column, value|
         table = default_table
 
+        if column.is_a?(Symbol) && klass.attribute_aliases.key?(column.to_s)
+          column = klass.attribute_aliases[column.to_s]
+        end
+
         if value.is_a?(Hash)
           if value.empty?
             queries << '1=0'

activerecord/test/cases/calculations_test.rb

@@ -28,6 +28,10 @@ def test_should_average_field
     assert_equal 53.0, value
   end
 
+  def test_should_resolve_aliased_attributes
+    assert_equal 318, Account.sum(:available_credit)
+  end
+
   def test_should_return_decimal_average_of_integer_field
     value = Account.average(:id)
     assert_equal 3.5, value
@@ -352,6 +356,10 @@ def test_count_with_distinct
     assert_equal 4, Account.select(:credit_limit).uniq.count
   end
 
+  def test_count_with_aliased_attribute
+    assert_equal 6, Account.count(:available_credit)
+  end
+
   def test_count_with_column_and_options_parameter
     assert_equal 2, Account.where("credit_limit = 50 AND firm_id IS NOT NULL").count(:firm_id)
   end
@@ -488,6 +496,10 @@ def test_pluck_in_relation
     assert_equal [contract.id], company.contracts.pluck(:id)
   end
 
+  def test_pluck_on_aliased_attribute
+    assert_equal 'The First Topic', Topic.order(:id).pluck(:heading).first
+  end
+
   def test_pluck_with_serialization
     t = Topic.create!(:content => { :foo => :bar })
     assert_equal [{:foo => :bar}], Topic.where(:id => t.id).pluck(:content)

activerecord/test/cases/finder_test.rb

@@ -47,7 +47,8 @@ def test_find_with_string
   def test_exists
     assert Topic.exists?(1)
     assert Topic.exists?("1")
-    assert Topic.exists?(:author_name => "David")
+    assert Topic.exists?(title: "The First Topic")
+    assert Topic.exists?(heading: "The First Topic")
     assert Topic.exists?(:author_name => "Mary", :approved => true)
     assert Topic.exists?(["parent_id = ?", 1])
     assert !Topic.exists?(45)

activerecord/test/cases/relation/where_test.rb

@@ -5,6 +5,7 @@
 require 'models/post'
 require 'models/comment'
 require 'models/edge'
+require 'models/topic'
 
 module ActiveRecord
   class WhereTest < ActiveRecord::TestCase
@@ -80,6 +81,13 @@ def test_polymorphic_sti_nested_where
       assert_equal expected.to_sql, actual.to_sql
     end
 
+    def test_aliased_attribute
+      expected = Topic.where(heading: 'The First Topic')
+      actual   = Topic.where(title: 'The First Topic')
+
+      assert_equal expected.to_sql, actual.to_sql
+    end
+
     def test_where_error
       assert_raises(ActiveRecord::StatementInvalid) do
         Post.where(:id => { 'posts.author_id' => 10 }).first

activerecord/test/models/company.rb

@@ -206,6 +206,8 @@ class Account < ActiveRecord::Base
   belongs_to :firm, :class_name => 'Company'
   belongs_to :unautosaved_firm, :foreign_key => "firm_id", :class_name => "Firm", :autosave => false
 
+  alias_attribute :available_credit, :credit_limit
+
   def self.destroyed_account_ids
     @destroyed_account_ids ||= Hash.new { |h,k| h[k] = [] }
   end