class Content {
...
}discriminator
Purpose
Customizes the discriminator column used in table-per-hierarchy inheritance mapping. Has no effect when using table-per-subclass inheritance mapping.
Examples
class PodCast extends Content {
...
static mapping = {
discriminator "audio"
}
}Description
Usage: discriminator(string/map)
Arguments:
-
column(optional) - The column name to store the discriminator -
value- The value to use for the discriminator -
formula(optional) - an SQL expression that is executed to evaluate the type of class. Use this orcolumnbut not both -
type(optional defaults to string) - the Hibernate type, used for the where clause condition to know if it needs to wrap it with '
By default when mapping inheritance Grails uses a single-table model where all classes share the same table. A discriminator column is used to determine the type for each row, by default the full class name. You can use the discriminator method to customize what’s stored:
class Content {
...
}class PodCast extends Content {
...
static mapping = {
discriminator "audio"
}
}You can also customize the discriminator column name:
class Content {
...
static mapping = {
discriminator column: "content_type"
}
}class PodCast extends Content {
...
static mapping = {
discriminator value: "audio"
}
}Or you can use a formula:
class Content {
...
static mapping = {
discriminator value: "1", type: "integer",
formula: "case when CLASS_TYPE in ('a', 'b', 'c') then 0 else 1 end",
}
}class PodCast extends Content {
...
static mapping = {
discriminator value: "0"
}
}