When running the alchemy scaffold on MySQL an error is generated on t…

…able

creation:

sqlalchemy.exc.OperationalError: (OperationalError) (1170, "BLOB/TEXT column 'name' used in key specification without a key length") '\nCREATE TABLE models (\n\tid INTEGER NOT NULL AUTO_INCREMENT, \n\tname TEXT, \n\tvalue INTEGER, \n\tPRIMARY KEY (id), \n\tUNIQUE (name)\n)\n\n' ()

MySQL (and MariaDB) doesn't allow an index of more than 255 characters. After
modifying the scaffold and creating a project, the following results:

> show create table models;
+--------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table  | Create Table                                                                                                                                                                                                                       |
+--------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| models | CREATE TABLE `models` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` text,
  `value` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `my_index` (`name`(255))
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=latin1 |
+--------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

A unique index is created on the name field, constrained to 255 characters.

When run on SQLite3:

sqlite> .schema models
CREATE TABLE models (
	id INTEGER NOT NULL,
	name TEXT,
	value INTEGER,
	PRIMARY KEY (id)
);
CREATE UNIQUE INDEX my_index ON models (name);

the mysql specific constraint is ignored and the table is created with a unique
index as desired.

pyramid/scaffolds/alchemy/+package+/models.py

@@ -1,5 +1,6 @@
 from sqlalchemy import (
     Column,
+    Index,
     Integer,
     Text,
     )
@@ -20,9 +21,11 @@
 class MyModel(Base):
     __tablename__ = 'models'
     id = Column(Integer, primary_key=True)
-    name = Column(Text, unique=True)
+    name = Column(Text)
     value = Column(Integer)
 
     def __init__(self, name, value):
         self.name = name
         self.value = value
+
+Index('my_index', MyModel.name, unique=True, mysql_length=255)