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(Quick Reference)

column

Purpose

Customizes a column definition

Examples

static mapping = {
        currency column: "currency", sqlType: "char", length: 3
    }

Description

Usage: property_name(map)

Arguments:

  • column - The name of the column as a String

  • sqlType (optional) - The underlying SQL type

  • enumType (optional) - The enum type in for type-safe Enum properties. Either ordinal or string.

  • index (optional) - The index name

  • unique (optional) - Whether it is unique

  • length (optional) - The length of the column

  • precision (optional) - The precision of the column

  • scale (optional) - The scale of the column

  • comment (optional) - The comment for the column (used to create the table DDL)

  • defaultValue (optional) - The database default value

By default GORM uses the property name and type to determine how to map a property in the database. For example a String property is typically mapped as a varchar(255) column. You can customize these with column configuration arguments:

static mapping = {
    currency column: "currency", sqlType: "char", length: 3
}

If you use a Hibernate type that requires multiple column definitions you can use the column method to define each column:

static mapping = {
    amount type: MonetaryUserType, {
        column name: "value"
        column name: "currency", sqlType: "char", length: 3
    }
}

Note that if you have a static method that is the same name as one of your properties you are trying to configure or you use the same property name as one of the static GORM methods this can lead to conflicts. To avoid this scenario scope the mapping configuration using the delegate property:

static mapping = {
    delegate.currency column: "currency", sqlType: "char", length: 3
}

Mapping an Enum

The next example illustrates the different options to map an enum.

Given the next code:

package demo

import groovy.transform.CompileStatic

@CompileStatic
class BootStrap {

    def init = { servletContext ->
        Book.saveAll(
            new Book(name: 'Grails 3 - Step by Step',
                     status: Status.NOT_SET),
            new Book(name: 'Grails 3 - A practical guide to application development',
                     status: Status.BORROWED),
            new Book(name: 'Falando de Grails',
                     status: Status.SOLD),
        )
    }
    def destroy = { }
}
package demo

import groovy.transform.CompileStatic

@CompileStatic
enum Status {
    NOT_SET(-1),
    BORROWED(0),
    SOLD(1),

    final int id
    private Status(int id) { this.id = id }
}

For enumType ordinal

package demo

class Book {
    String name
    Status status

    static mapping = {
        status enumType: 'ordinal'
    }
}

The enum will be mapped in the database as:

ID

VERSION

NAME

STATUS

1

0

Grails 3 - Step by Step

0

2

0

Grails 3 - A practical guide to application development

1

3

0

Falando de Grails

2

For enumType identity

package demo

class Book {
    String name
    Status status

    static mapping = {
        status enumType: 'identity'
    }
}

The enum will be mapped in the database as:

ID

VERSION

NAME

STATUS

1

0

Grails 3 - Step by Step

-1

2

0

Grails 3 - A practical guide to application development

0

3

0

Falando de Grails

1

For enumType string

package demo

class Book {
    String name
    Status status

    static mapping = {
        status enumType: 'string'
    }
}

The enum will be mapped in the database as:

ID

VERSION

NAME

STATUS

1

0

Grails 3 - Step by Step

NOT_SET

2

0

Grails 3 - A practical guide to application development

BORROWED

3

0

Falando de Grails

SOLD