Fix GH #3931. A text type column with limit is returned incorrect data type on mysql.

activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

@@ -474,15 +474,27 @@ def rename_column(table_name, column_name, new_column_name) #:nodoc:
 
       # Maps logical Rails types to MySQL-specific data types.
       def type_to_sql(type, limit = nil, precision = nil, scale = nil)
-        return super unless type.to_s == 'integer'
-
-        case limit
-        when 1; 'tinyint'
-        when 2; 'smallint'
-        when 3; 'mediumint'
-        when nil, 4, 11; 'int(11)'  # compatibility with MySQL default
-        when 5..8; 'bigint'
-        else raise(ActiveRecordError, "No integer type has byte size #{limit}")
+        case type.to_s
+        when 'integer'
+          case limit
+          when 1; 'tinyint'
+          when 2; 'smallint'
+          when 3; 'mediumint'
+          when nil, 4, 11; 'int(11)'  # compatibility with MySQL default
+          when 5..8; 'bigint'
+          else raise(ActiveRecordError, "No integer type has byte size #{limit}")
+          end
+        when 'text'
+          case limit
+          when nil; 'text'
+          when 0..0xff; 'tinytext'
+          when 0x100..0xffff; 'text'
+          when 0x10000..0xffffff; 'mediumtext'
+          when 0x1000000..0xffffffff; 'longtext'
+          else raise(ActiveRecordError, "No text type has character length #{limit}")
+          end
+        else
+          super
         end
       end
 

activerecord/test/cases/migration_test.rb

@@ -944,4 +944,35 @@ def test_copying_migrations_to_empty_directory
   ensure
     clear
   end
+
+  if current_adapter?(:MysqlAdapter) or current_adapter?(:Mysql2Adapter)
+    def test_text_column_with_limits
+      assert_nothing_raised do
+        Person.connection.create_table :testings do |t|
+          t.column :tinytext,   :text, :limit => 0xff
+          t.column :text      , :text, :limit => 0xffff
+          t.column :text_default, :text
+          t.column :mediumtext, :text, :limit => 0xffffff
+          t.column :longtext,   :text, :limit => 0xffffffff
+        end
+      end
+
+      columns = Person.connection.columns(:testings)
+
+      tiny         = columns.detect { |c| c.name == "tinytext"     }
+      text         = columns.detect { |c| c.name == "text"         }
+      text_default = columns.detect { |c| c.name == "text_default" }
+      medium       = columns.detect { |c| c.name == "mediumtext"   }
+      long         = columns.detect { |c| c.name == "longtext"     }
+
+      assert_match 'tinytext',   tiny.sql_type
+      assert_match 'text',       text.sql_type
+      assert_match 'text',       text_default.sql_type
+      assert_match 'mediumtext', medium.sql_type
+      assert_match 'longtext',   long.sql_type
+    ensure
+      Person.connection.drop_table :testings rescue nil
+    end
+  end
+
 end