Client and backend. This class is shared: the same code is compiled into your app and into your server, so everything on this page works in both.

@Retention(CLASS) @Target({FIELD})

public @interface ElementCollection

Mapping for an owned collection of scalar values.

Methods

`public abstract` `FetchType fetch() default FetchType.LAZY`	Controls relationship initialization.
`public abstract` `String column() default "element_value"`	Names the scalar value column in the collection table.
`public abstract` `String joinColumn() default ""`	Names the column that holds the owner’s id in the collection table.
`public abstract` `String type() default ""`	The SQL type of the value column, written into `CREATE TABLE` as it is, like `Column.type` – for example `LONGTEXT` – and validated against the existing column the same way.
`public abstract` `String positionColumn() default "element_position"`	Names the column that stores each element’s position, which keys the table together with the owner and keeps a List’s order and duplicates.

Method details

fetch

public abstract FetchType fetch() default FetchType.LAZY

Controls relationship initialization.

Returns

fetch policy; EAGER for to-one and LAZY for collections by default

column

public abstract String column() default "element_value"

Names the scalar value column in the collection table.

Returns

column name; element_value by default

joinColumn

public abstract String joinColumn() default ""

Names the column that holds the owner’s id in the collection table. Empty keeps JoinTable.joinColumn when that is set and owner_id otherwise; naming the column in both places is a build error.

Returns

owner column name; empty for the default

type

public abstract String type() default ""

The SQL type of the value column, written into CREATE TABLE as it is, like Column.type – for example LONGTEXT – and validated against the existing column the same way.

Returns

SQL type; empty for the dialect’s type for the element class

positionColumn

public abstract String positionColumn() default "element_position"

Names the column that stores each element’s position, which keys the table together with the owner and keeps a List’s order and duplicates.

An empty name maps a Set to a table with no position column, keyed by the owner and the value – the layout JPA providers create, so a table one of them made can be adopted as it is. Such a Set cannot hold null, and a text value is limited to 255 characters, like any text key.

Returns

column name; element_position by default, empty for none