Add support for CollectionAssociation#delete by Fixnum or String

I found the next issue between CollectionAssociation `delete`
and `destroy`.

    class Person < ActiveRecord::Base
      has_many :pets
    end

    person.pets.destroy(1)
    # => OK, returns the destroyed object

    person.pets.destroy("2")
    # => OK, returns the destroyed object

    person.pets.delete(1)
    # => ActiveRecord::AssociationTypeMismatch

    person.pets.delete("2")
    # => ActiveRecord::AssociationTypeMismatch

Adding support for deleting with a fixnum or string like
`destroy` method.

2 files changed, 27 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/associations/collection_association.rb b/activerecord/lib/active_record/associations/collection_association.rb
index 4ec176e641..e94fe35170 100644
--- a/activerecord/lib/active_record/associations/collection_association.rb
+++ b/activerecord/lib/active_record/associations/collection_association.rb
@@ -230,6 +230,7 @@ module ActiveRecord
             delete_records(:all, dependent)
           end
         else
+          records = find(records) if records.any? { |record| record.kind_of?(Fixnum) || record.kind_of?(String) }
           delete_or_destroy(records, dependent)
         end
       end
diff --git a/activerecord/lib/active_record/associations/collection_proxy.rb b/activerecord/lib/active_record/associations/collection_proxy.rb
index 294aa63f75..2176fc4e40 100644
--- a/activerecord/lib/active_record/associations/collection_proxy.rb
+++ b/activerecord/lib/active_record/associations/collection_proxy.rb
@@ -469,6 +469,8 @@ module ActiveRecord
       #
       # :call-seq:
       #   delete(*records)
+      #   delete(*fixnum_ids)
+      #   delete(*string_ids)
       #
       # Deletes the +records+ supplied and removes them from the collection. For
       # +has_many+ associations, the deletion is done according to the strategy
@@ -560,6 +562,30 @@ module ActiveRecord
       #
       #   Pet.find(1)
       #   # => ActiveRecord::RecordNotFound: Couldn't find Pet with id=1
+      #
+      # You can pass +Fixnum+ or +String+ values, it finds the records
+      # responding to the +id+ and executes delete on them.
+      #
+      #   class Person < ActiveRecord::Base
+      #     has_many :pets
+      #   end
+      #
+      #   person.pets.size # => 3
+      #   person.pets
+      #   # => [
+      #   #       #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
+      #   #       #<Pet id: 2, name: "Spook", person_id: 1>,
+      #   #       #<Pet id: 3, name: "Choo-Choo", person_id: 1>
+      #   #    ]
+      #
+      #   person.pets.delete("1")
+      #   # => [#<Pet id: 1, name: "Fancy-Fancy", person_id: 1>]
+      #
+      #   person.pets.delete(2, 3)
+      #   # => [
+      #   #       #<Pet id: 2, name: "Spook", person_id: 1>,
+      #   #       #<Pet id: 3, name: "Choo-Choo", person_id: 1>
+      #   #    ]
 
       ##
       # :method: destroy