Package graphql.execution

Class SubscriptionExecutionStrategy

java.lang.Object

graphql.execution.ExecutionStrategy

graphql.execution.SubscriptionExecutionStrategy

@PublicApi
public class SubscriptionExecutionStrategy
extends ExecutionStrategy

An execution strategy that implements graphql subscriptions by using reactive-streams as the output result of the subscription query.

Afterwards each object delivered on that stream will be mapped via running the original selection set over that object and hence producing an ExecutionResult just like a normal graphql query.

See https://spec.graphql.org/draft/#sec-Subscription

See https://www.reactive-streams.org/

Field Summary

Fields

Modifier and Type	Field	Description
static java.lang.String	KEEP_SUBSCRIPTION_EVENTS_ORDERED	If a boolean value is placed into the GraphQLContext with this key then the order of the subscription events can be controlled.

Fields inherited from class graphql.execution.ExecutionStrategy

dataFetcherExceptionHandler, executionStepInfoFactory, fieldCollector

Constructor Summary

Constructors

Constructor	Description
SubscriptionExecutionStrategy()
SubscriptionExecutionStrategy(DataFetcherExceptionHandler dataFetcherExceptionHandler)

Method Summary

Modifier and Type	Method	Description
java.util.concurrent.CompletableFuture<ExecutionResult>	execute(ExecutionContext executionContext, ExecutionStrategyParameters parameters)	This is the entry point to an execution strategy.

Methods inherited from class graphql.execution.ExecutionStrategy

assertNonNullFieldPrecondition, assertNonNullFieldPrecondition, completeField, completeValue, completeValueForEnum, completeValueForList, completeValueForList, completeValueForNull, completeValueForObject, completeValueForScalar, createExecutionStepInfo, executeObject, fetchField, getFieldDef, getFieldDef, getNormalizedField, handleFetchingException, handleNonNullException, handleValueException, mkNameForPath, mkNameForPath, mkNameForPath, resolveField, resolveFieldWithInfo, resolveType, toIterable, unboxPossibleDataFetcherResult

Methods inherited from class java.lang.Object

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

Field Detail

KEEP_SUBSCRIPTION_EVENTS_ORDERED

public static final java.lang.String KEEP_SUBSCRIPTION_EVENTS_ORDERED

If a boolean value is placed into the GraphQLContext with this key then the order of the subscription events can be controlled. By default, subscription events are published as the graphql subselection calls complete, and not in the order they originally arrived from the source publisher. But this can be changed to Boolean.TRUE to keep them in order.

See Also:

Constant Field Values

Constructor Detail

SubscriptionExecutionStrategy

public SubscriptionExecutionStrategy()

SubscriptionExecutionStrategy

public SubscriptionExecutionStrategy(DataFetcherExceptionHandler dataFetcherExceptionHandler)

Method Detail

execute

public java.util.concurrent.CompletableFuture<ExecutionResult> execute(ExecutionContext executionContext,
                                                                       ExecutionStrategyParameters parameters)
                                                                throws NonNullableFieldWasNullException

Description copied from class: ExecutionStrategy

This is the entry point to an execution strategy. It will be passed the fields to execute and get values for.

Specified by:

execute in class ExecutionStrategy

Parameters:

executionContext - contains the top level execution parameters

parameters - contains the parameters holding the fields to be executed and source object

Returns:

a promise to an ExecutionResult

Throws:

NonNullableFieldWasNullException - in the future if a non-null field resolves to a null value