Deal with MySQL's quirky handling of defaults and blob/text columns

[#1043 state:committed]

Signed-off-by: Jeremy Kemper <jeremy@bitsweat.net>

3 files changed, 11 insertions, 2 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
index 22304edfc9..58992f91da 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
@@ -40,6 +40,10 @@ module ActiveRecord
         type == :integer || type == :float || type == :decimal
       end
 
+      def has_default?
+        !default.nil?
+      end
+
       # Returns the Ruby class that corresponds to the abstract data type.
       def klass
         case type
diff --git a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
index c2a0fb72bf..a26fd02b90 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
@@ -80,7 +80,7 @@ module ActiveRecord
       def extract_default(default)
         if type == :binary || type == :text
           if default.blank?
-            nil
+            return null ? nil : ''
           else
             raise ArgumentError, "#{type} columns cannot have a default value: #{default.inspect}"
           end
@@ -91,6 +91,11 @@ module ActiveRecord
         end
       end
 
+      def has_default?
+        return false if type == :binary || type == :text #mysql forbids defaults on blob and text columns
+        super
+      end
+
       private
         def simplified_type(field_type)
           return :boolean if MysqlAdapter.emulate_booleans && field_type.downcase.index("tinyint(1)")
diff --git a/activerecord/lib/active_record/schema_dumper.rb b/activerecord/lib/active_record/schema_dumper.rb
index b90ed88c6b..4f96e225c1 100644
--- a/activerecord/lib/active_record/schema_dumper.rb
+++ b/activerecord/lib/active_record/schema_dumper.rb
@@ -102,7 +102,7 @@ HEADER
             spec[:precision] = column.precision.inspect if !column.precision.nil?
             spec[:scale]     = column.scale.inspect if !column.scale.nil?
             spec[:null]      = 'false' if !column.null
-            spec[:default]   = default_string(column.default) if !column.default.nil?
+            spec[:default]   = default_string(column.default) if column.has_default?
             (spec.keys - [:name, :type]).each{ |k| spec[k].insert(0, "#{k.inspect} => ")}
             spec
           end.compact