Annotation Interface BatchMapping

@Target(METHOD)
@Retention(RUNTIME)
@Documented
public @interface BatchMapping

Annotation for a handler method that batch loads field values, given a list of source/parent values. For example:

 @BatchMapping
 public Mono<Map<Book, Author>> author(List<Book> books) {
     // ...
 }
 

The annotated method is registered as a batch loading function via BatchLoaderRegistry, and along with it, a DataFetcher for the field is registered transparently that looks up the field value through the registered DataLoader.

Effectively, a shortcut for:

 @Controller
 public class BookController {

     public BookController(BatchLoaderRegistry registry) {
         registry.forTypePair(Long.class, Author.class).registerMappedBatchLoader((ids, environment) -> ...);
     }

     @SchemaMapping
     public CompletableFuture<Author> author(Book book, DataLoader<Long, Author> dataLoader) {
         return dataLoader.load(book.getAuthorId());
     }

 }
 

In addition to returning Mono<Map<K,T>>, an @BatchMapping method can also return Flux<T>. However, in that case the returned sequence of values must match the number and order of the input keys. See BatchLoader and MappedBatchLoader for more details.

Since:

1.0.0

Author:

Rossen Stoyanchev

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element	Description
String	field	Customize the name of the GraphQL field to bind to.
int	maxBatchSize	Set the maximum number of keys to include a single batch, before splitting into multiple batches of keys to load.
String	typeName	Customizes the name of the source/parent type for the GraphQL field.
String	value	Effectively an alias for field().

Element Details

field

@AliasFor("value")
String field

Customize the name of the GraphQL field to bind to.

By default, if not specified, this is initialized from the method name.

Default:

""

value

@AliasFor("field")
String value

Effectively an alias for field().

Default:

""

typeName

String typeName

Customizes the name of the source/parent type for the GraphQL field.

By default, if not specified, it is based on the simple class name of the List of source/parent values injected into the handler method.

The value for this attribute can also be inherited from a class-level @SchemaMapping. When used on both levels, the one here overrides the one at the class level.

Default:

""

maxBatchSize

int maxBatchSize

Set the maximum number of keys to include a single batch, before splitting into multiple batches of keys to load.

By default this is -1 in which case there is no limit.

Since:

1.1.0

Default:

-1