joinTable
Purpose
Customizes the join table used for undirectional one-to-many, many-to-many and primitive collection types.
Examples
Basic collection type:
class Book { static hasMany = [chapterPageCounts: Integer]
static mapping = {
chapterPageCounts indexColumn: [name: "chapter_number", type: Integer],
joinTable: [column: "page_count"]
}
Enum collection types:
enum VehicleStatus { OFF, IDLING, ACCELERATING, DECELERATING }class Truck { static hasMany = [states: VehicleStatus]
static mapping = {
states joinTable: [name: 'VEHICLE_STATUS_LOG',
key: 'TRUCK_ID', column: 'STATUS']
}
}
Many-to-many:
class Book { String title
static belongsTo = Author
static hasMany = [authors: Author]
static mapping = {
authors joinTable: [name: "mm_author_books", key: 'mm_book_id' ]
}
}
class Author { String name
static hasMany = [books: Book]
static mapping = {
books joinTable: [name: "mm_author_books", key: 'mm_author_id']
}
}
Unidirectional One-to-many:
class Employee { static hasMany = [projects: Project]
static mapping = {
projects joinTable: [name: 'EMP_PROJ',
column: 'PROJECT_ID',
key: 'EMPLOYEE_ID']
}
}
class Project { }Description
Usage: association_name(joinTable:map)
Arguments:
name- The table namekey(optional) - The foreign keycolumn(optional) - The inverse column
GORM has various strategies for mapping association types. Some of them, such as basic collection types and many-to-many associations, use a join table. You can customize how this join table is created using the joinTable argument.