Don't carry default value when changing column for a binary type on MySQL [#3234 state:resolved]

Signed-off-by: José Valim <jose.valim@gmail.com>

activerecord/lib/active_record/connection_adapters/mysql_adapter.rb

@@ -513,7 +513,7 @@ module ActiveRecord
       def change_column(table_name, column_name, type, options = {}) #:nodoc:
         column = column_for(table_name, column_name)
 
-        unless options_include_default?(options)
+        if has_default?(type) && !options_include_default?(options)
           options[:default] = column.default
         end
 
@@ -675,6 +675,10 @@ module ActiveRecord
           end
           column
         end
+
+        def has_default?(sql_type)
+          sql_type =~ :binary || sql_type == :text #mysql forbids defaults on blob and text columns
+        end
     end
   end
 end

activerecord/test/cases/migration_test.rb

@@ -860,6 +860,16 @@ if ActiveRecord::Base.connection.supports_migrations?
       assert_equal "Tester", Person.new.first_name
     end
 
+    def test_change_column_type_default_should_change
+      old_columns = Person.connection.columns(Person.table_name, "#{name} Columns")
+      assert !old_columns.find { |c| c.name == 'data' }
+
+      assert_nothing_raised do
+        Person.connection.add_column "people", "data", :string, :default => ''
+        Person.connection.change_column "people", "data", :binary
+      end
+    end
+
     def test_change_column_quotes_column_names
       Person.connection.create_table :testings do |t|
         t.column :select, :string