Package org.forum.server.specific_code

Class DataFetchersDelegateBoardImpl

java.lang.Object

org.forum.server.specific_code.DataFetchersDelegateBoardImpl

All Implemented Interfaces:

DataFetchersDelegateBoard

@Component
public class DataFetchersDelegateBoardImpl
extends Object
implements DataFetchersDelegateBoard

This class implements the access to the database : there are so many ways to do this, that the developper has still work to do. But all the GraphQL boilerplate is generated.
The GraphQLDataFetchersDelegate interface is generated from the given schema

Author:

etienne-sf

Field Summary

Fields

Modifier and Type	Field	Description
protected org.slf4j.Logger	logger	The logger for this instance

Constructor Summary

Constructors

Constructor	Description
DataFetchersDelegateBoardImpl()

Method Summary

Modifier and Type	Method	Description
Object	topics(graphql.schema.DataFetchingEnvironment dataFetchingEnvironment, org.dataloader.DataLoader<Long,Topic> dataLoader, Board origin, Date since)	This method loads the data for Board.topics.
List<Topic>	topics(graphql.schema.DataFetchingEnvironment dataFetchingEnvironment, Board source, Date since)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.forum.server.graphql.util.DataFetchersDelegateBoard

batchLoader, unorderedReturnBatchLoader

Field Details

logger

protected org.slf4j.Logger logger

The logger for this instance

Constructor Details

DataFetchersDelegateBoardImpl

public DataFetchersDelegateBoardImpl()

Method Details

topics

public List<Topic> topics(graphql.schema.DataFetchingEnvironment dataFetchingEnvironment,
 Board source,
 Date since)

topics

public Object topics(graphql.schema.DataFetchingEnvironment dataFetchingEnvironment,
 org.dataloader.DataLoader<Long,Topic> dataLoader,
 Board origin,
 Date since)

Description copied from interface: DataFetchersDelegateBoard

This method loads the data for Board.topics. It may return whatever is accepted by the Spring Controller, that is:

• A resolved value of any type (typically, a List<org.forum.server.graphql.Topic>)
• Mono and Flux for asynchronous value(s). Supported for controller methods and for any DataFetcher as described in Reactive DataFetcher. This would typically be a Mono<List<org.forum.server.graphql.Topic>> or a Flux<List<org.forum.server.graphql.Topic>>
• Kotlin coroutine and Flow are adapted to Mono and Flux
• java.util.concurrent.Callable to have the value(s) produced asynchronously. For this to work, AnnotatedControllerConfigurer must be configured with an Executor. This would typically by a Callable<List<org.forum.server.graphql.Topic>>

As a complement to the spring-graphql documentation, you may also return:

• A CompletableFuture<?>, for instance CompletableFuture<List<org.forum.server.graphql.Topic>>. This allows to use graphql-java java-dataloader to highly optimize the number of requests to the server. The principle is this one: The data loader collects all the data to load, avoid to load several times the same data, and allows parallel execution of the queries, if multiple queries are to be run.
• A Publisher (instead of a Flux), for Subscription for instance

Specified by:

topics in interface DataFetchersDelegateBoard

Parameters:

dataFetchingEnvironment - The GraphQL DataFetchingEnvironment. It gives you access to the full GraphQL context for this DataFetcher

dataLoader - The DataLoader allows to load several data in one query. It allows to solve the (n+1) queries issues, and greatly optimizes the response time.
You'll find more informations here: https://github.com/graphql-java/java-dataloader

origin - The object from which the field is fetch. In other word: the aim of this data fetcher is to fetch the topics attribute of the origin, which is an instance of {ObjectType {name:Board, fields:{Field{name:id, type:ID!, params:[]},Field{name:name, type:String!, params:[]},Field{name:publiclyAvailable, type:Boolean, params:[]},Field{name:topics, type:[Topic]!, params:[since:Date]}}, comments ""}. It depends on your data modle, but it typically contains the id to use in the query.

since - The input parameter sent in the query by the GraphQL consumer, as defined in the GraphQL schema.