Merge pull request #6544 from flexoid/issue-6431

exists?(false) returns false

activerecord/CHANGELOG.md

 ## Rails 4.0.0 (unreleased) ##
 
+*   `FinderMethods#exists?` now returns `false` with the `false` argument.
+
+    *Egor Lynko*
+
 *   Added support for specifying the precision of a timestamp in the postgresql
     adapter. So, instead of having to incorrectly specify the precision using the
     `:limit` option, you may use `:precision`, as intended. For example, in a migration:

activerecord/lib/active_record/relation/finder_methods.rb

@@ -170,19 +170,19 @@ def all
     #   Person.exists?(['name LIKE ?', "%#{query}%"])
     #   Person.exists?(:name => "David")
     #   Person.exists?
-    def exists?(id = false)
-      id = id.id if ActiveRecord::Model === id
-      return false if id.nil?
+    def exists?(conditions = :none)
+      conditions = conditions.id if ActiveRecord::Model === conditions
+      return false if !conditions
 
       join_dependency = construct_join_dependency_for_association_find
       relation = construct_relation_for_association_find(join_dependency)
       relation = relation.except(:select, :order).select("1 AS one").limit(1)
 
-      case id
+      case conditions
       when Array, Hash
-        relation = relation.where(id)
+        relation = relation.where(conditions)
       else
-        relation = relation.where(table[primary_key].eq(id)) if id
+        relation = relation.where(table[primary_key].eq(conditions)) if conditions != :none
       end
 
       connection.select_value(relation, "#{name} Exists", relation.bind_values)

activerecord/test/cases/finder_test.rb

@@ -55,6 +55,10 @@ def test_exists_returns_true_with_one_record_and_no_args
     assert Topic.exists?
   end
 
+  def test_exists_returns_false_with_false_arg
+    assert !Topic.exists?(false)
+  end
+
   # exists? should handle nil for id's that come from URLs and always return false
   # (example: Topic.exists?(params[:id])) where params[:id] is nil
   def test_exists_with_nil_arg