Booleans in grails aren't persisted?

Question

Hello,

I'm developing a small application on Grails 1.3.5 and I run into this very strange problem.

My domain classes feature some boolean typed fields. None of these fields is persisted when creating a new instance (and saving it of course).

For example, I have this domain class "Employee", defined as follows (simplified):

class Employee {
 String name
 boolean present
} 

When I create a new instance of that class and I persist it, the name is saved, but the present-named boolean isn't.

def newEmp = new Employee(name: "me", present: true)
newEmp.save(failOnError: true, flush: true)

When saving, no error is thrown. However, in the database (I use MySQL) the binary column "present" always remains empty.

What could be causing this? This happens alongs all my domain classes.

Answer 1

How are you querying the column? By 'empty' do you mean null? By default Hibernate + MySQL will persist booleans as a bit with value 0 or 1 so when running "select * from foo" the values look blank. You can cast to a number though:

select name, CAST(present AS UNSIGNED) from employee

Another thing you can do is use a custom Dialect that persists using a 'boolean' type instead of a bit:

package com.yourcompany.yourapp

import java.sql.Types
import org.hibernate.dialect.MySQL5InnoDBDialect

class MyDialect extends MySQL5InnoDBDialect {
   public MyDialect() {
      registerColumnType(Types.BIT, "boolean")
   }
}

Register this in DataSource.groovy as

dataSource {
   pooled = true
   driverClassName = 'com.mysql.jdbc.Driver'
   username = '...'
   password = '...'
   dialect = com.yourcompany.yourapp.MyDialect
}

Answer 2

Chances are the problem is somewhere else. I wrote an application in Grails 1.2 that use booleans and MySql and had no persistence issues.