Package io.github.joselion.springr2dbcrelationships.annotations

Annotation Interface ManyToMany

@Documented
@Value("null")
@Retention(RUNTIME)
@Target({FIELD,PARAMETER,ANNOTATION_TYPE})
public @interface ManyToMany

Marks a field to have a many-to-many relationship.

This annotation also adds the @Transient and @Value("null") annotations to the field.

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element	Description
boolean	deleteOrphans	Whether "orphan" entities are deleted or not.
String	joinTable	Specifies the name of the join table responsible for the many-to-many relationship between two tables.
String	linkedBy	Specifies the name of the "foreign key" column that maps the join table with the linked table.
boolean	linkOnly	Whether the associated entities are only linked to the join table or not.
String	mappedBy	Specifies the name of the "foreign key" column that maps the annotated field's entity with the join table.
boolean	readonly	Whether the associated entities are read-only or not, meaning they are never persisted or linked.
String	sortBy	Specifies the column used to sort the populated associated entities.
org.springframework.data.domain.Sort.Direction	sortIn	Specifies in which direction the populated children entities are sorted.

Element Details

deleteOrphans

boolean deleteOrphans

Whether "orphan" entities are deleted or not. Defaults to false.

Usually, many-to-many relationships are not mutually exclusive to each other, meaning that one can exist without the other even when they are not linked in their join table. In this context, "orphans" refers to all entities no longer linked to the current entity. By default, the annotation will only delete the links to the "orphan" entities in the join table. Setting this option to true will also delete the "orphan" entities.

Returns:

true if "orphan" entities are deleted, false otherwise

ApiNote:

given the nature of many-to-many relationships, setting this option to true is highly discouraged as it can produce unexpected results, especially in bidirectional associations

Default:

false

joinTable

String joinTable

Specifies the name of the join table responsible for the many-to-many relationship between two tables. This is optional if the name of the join table matches the names of both related tables joined by an underscore (in any order).

For example, given a table author and a table book, the join table for the relationship can either be inferred as author_book or as book_author.

Returns:

the name of the relationship join table

Default:

""

linkedBy

String linkedBy

Specifies the name of the "foreign key" column that maps the join table with the linked table. This is optional if the column's name matches the linked table name followed by an _id suffix.

For example, given a table author and a table book, and given the annotation is used in a field of author's entity, we can say the linked table is book and its "foreign key" column in the join table is inferred as book_id.

Returns:

the name of the column linking the join table

Default:

""

linkOnly

boolean linkOnly

Whether the associated entities are only linked to the join table or not. Defaults to false.

Link-only means the associated entities already exist. The annotation will only create the link in the join table column when required. The associated entities are never updated.

Returns:

true if the associated entities are link-only, false otherwise

Default:

false

mappedBy

String mappedBy

Specifies the name of the "foreign key" column that maps the annotated field's entity with the join table. This is optional if the column's name matches the entity's table name followed by an _id suffix.

For example, given a table author and a table book, and given the annotation is used in a field of author's entity, the "foreign key" column in the join table is inferred as author_id.

Returns:

the name of the column mapping the join table

Default:

""

readonly

boolean readonly

Whether the associated entities are read-only or not, meaning they are never persisted or linked. Defaults to false.

Returns:

true if the associated entities are read-only, false otherwise

Default:

false

sortBy

String sortBy

Specifies the column used to sort the populated associated entities.

By default, the annotation tries to find the field associated with Auditable.getCreatedDate() or annotated with @CreatedDate. If none can be found, it'll try to find a "created_at" column as a last resort. If all of that fails, the children will be unsorted.

Returns:

the sorting column name

Default:

""

sortIn

org.springframework.data.domain.Sort.Direction sortIn

Specifies in which direction the populated children entities are sorted. Defaults to Sort.Direction.DESC.

Returns:

the sort direction

Default:

DESC