ExecutionStrategy.java
package graphql.execution;
import com.google.common.collect.ImmutableList;
import graphql.ExecutionResult;
import graphql.ExecutionResultImpl;
import graphql.GraphQLError;
import graphql.Internal;
import graphql.PublicSpi;
import graphql.SerializationError;
import graphql.TrivialDataFetcher;
import graphql.TypeMismatchError;
import graphql.UnresolvedTypeError;
import graphql.collect.ImmutableKit;
import graphql.execution.directives.QueryDirectives;
import graphql.execution.directives.QueryDirectivesImpl;
import graphql.execution.instrumentation.Instrumentation;
import graphql.execution.instrumentation.InstrumentationContext;
import graphql.execution.instrumentation.parameters.InstrumentationFieldCompleteParameters;
import graphql.execution.instrumentation.parameters.InstrumentationFieldFetchParameters;
import graphql.execution.instrumentation.parameters.InstrumentationFieldParameters;
import graphql.extensions.ExtensionsBuilder;
import graphql.introspection.Introspection;
import graphql.language.Argument;
import graphql.language.Field;
import graphql.normalized.ExecutableNormalizedField;
import graphql.normalized.ExecutableNormalizedOperation;
import graphql.schema.CoercingSerializeException;
import graphql.schema.DataFetcher;
import graphql.schema.DataFetchingEnvironment;
import graphql.schema.DataFetchingFieldSelectionSet;
import graphql.schema.DataFetchingFieldSelectionSetImpl;
import graphql.schema.GraphQLArgument;
import graphql.schema.GraphQLCodeRegistry;
import graphql.schema.GraphQLEnumType;
import graphql.schema.GraphQLFieldDefinition;
import graphql.schema.GraphQLObjectType;
import graphql.schema.GraphQLOutputType;
import graphql.schema.GraphQLScalarType;
import graphql.schema.GraphQLSchema;
import graphql.schema.GraphQLType;
import graphql.schema.LightDataFetcher;
import graphql.util.FpKit;
import graphql.util.LogKit;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.OptionalInt;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionException;
import java.util.function.Function;
import java.util.function.Supplier;
import static graphql.execution.Async.exceptionallyCompletedFuture;
import static graphql.execution.ExecutionStepInfo.newExecutionStepInfo;
import static graphql.execution.FieldCollectorParameters.newParameters;
import static graphql.execution.FieldValueInfo.CompleteValueType.ENUM;
import static graphql.execution.FieldValueInfo.CompleteValueType.LIST;
import static graphql.execution.FieldValueInfo.CompleteValueType.NULL;
import static graphql.execution.FieldValueInfo.CompleteValueType.OBJECT;
import static graphql.execution.FieldValueInfo.CompleteValueType.SCALAR;
import static graphql.execution.instrumentation.SimpleInstrumentationContext.nonNullCtx;
import static graphql.schema.DataFetchingEnvironmentImpl.newDataFetchingEnvironment;
import static graphql.schema.GraphQLTypeUtil.isEnum;
import static graphql.schema.GraphQLTypeUtil.isList;
import static graphql.schema.GraphQLTypeUtil.isScalar;
import static java.util.concurrent.CompletableFuture.completedFuture;
/**
* An execution strategy is give a list of fields from the graphql query to execute and find values for using a recursive strategy.
* <pre>
* query {
* friends {
* id
* name
* friends {
* id
* name
* }
* }
* enemies {
* id
* name
* allies {
* id
* name
* }
* }
* }
*
* </pre>
* <p>
* Given the graphql query above, an execution strategy will be called for the top level fields 'friends' and 'enemies' and it will be asked to find an object
* to describe them. Because they are both complex object types, it needs to descend down that query and start fetching and completing
* fields such as 'id','name' and other complex fields such as 'friends' and 'allies', by recursively calling to itself to execute these lower
* field layers
* <p>
* The execution of a field has two phases, first a raw object must be fetched for a field via a {@link DataFetcher} which
* is defined on the {@link GraphQLFieldDefinition}. This object must then be 'completed' into a suitable value, either as a scalar/enum type via
* coercion or if it's a complex object type by recursively calling the execution strategy for the lower level fields.
* <p>
* The first phase (data fetching) is handled by the method {@link #fetchField(ExecutionContext, ExecutionStrategyParameters)}
* <p>
* The second phase (value completion) is handled by the methods {@link #completeField(ExecutionContext, ExecutionStrategyParameters, FetchedValue)}
* and the other "completeXXX" methods.
* <p>
* The order of fields fetching and completion is up to the execution strategy. As the graphql specification
* <a href="https://spec.graphql.org/October2021/#sec-Normal-and-Serial-Execution">https://spec.graphql.org/October2021/#sec-Normal-and-Serial-Execution</a> says:
* <blockquote>
* Normally the executor can execute the entries in a grouped field set in whatever order it chooses (often in parallel). Because
* the resolution of fields other than top-level mutation fields must always be side effect-free and idempotent, the
* execution order must not affect the result, and hence the server has the freedom to execute the
* field entries in whatever order it deems optimal.
* </blockquote>
* <p>
* So in the case above you could execute the fields depth first ('friends' and its sub fields then do 'enemies' and its sub fields or it
* could do breadth first ('fiends' and 'enemies' data fetch first and then all the sub fields) or in parallel via asynchronous
* facilities like {@link CompletableFuture}s.
* <p>
* {@link #execute(ExecutionContext, ExecutionStrategyParameters)} is the entry point of the execution strategy.
*/
@PublicSpi
@SuppressWarnings("FutureReturnValueIgnored")
public abstract class ExecutionStrategy {
private static final Logger log = LoggerFactory.getLogger(ExecutionStrategy.class);
private static final Logger logNotSafe = LogKit.getNotPrivacySafeLogger(ExecutionStrategy.class);
protected final FieldCollector fieldCollector = new FieldCollector();
protected final ExecutionStepInfoFactory executionStepInfoFactory = new ExecutionStepInfoFactory();
private final ResolveType resolvedType = new ResolveType();
protected final DataFetcherExceptionHandler dataFetcherExceptionHandler;
/**
* The default execution strategy constructor uses the {@link SimpleDataFetcherExceptionHandler}
* for data fetching errors.
*/
protected ExecutionStrategy() {
dataFetcherExceptionHandler = new SimpleDataFetcherExceptionHandler();
}
/**
* The consumers of the execution strategy can pass in a {@link DataFetcherExceptionHandler} to better
* decide what do when a data fetching error happens
*
* @param dataFetcherExceptionHandler the callback invoked if an exception happens during data fetching
*/
protected ExecutionStrategy(DataFetcherExceptionHandler dataFetcherExceptionHandler) {
this.dataFetcherExceptionHandler = dataFetcherExceptionHandler;
}
/**
* This is the entry point to an execution strategy. It will be passed the fields to execute and get values for.
*
* @param executionContext contains the top level execution parameters
* @param parameters contains the parameters holding the fields to be executed and source object
*
* @return a promise to an {@link ExecutionResult}
*
* @throws NonNullableFieldWasNullException in the future if a non null field resolves to a null value
*/
public abstract CompletableFuture<ExecutionResult> execute(ExecutionContext executionContext, ExecutionStrategyParameters parameters) throws NonNullableFieldWasNullException;
/**
* Called to fetch a value for a field and resolve it further in terms of the graphql query. This will call
* #fetchField followed by #completeField and the completed {@link ExecutionResult} is returned.
* <p>
* An execution strategy can iterate the fields to be executed and call this method for each one
* <p>
* Graphql fragments mean that for any give logical field can have one or more {@link Field} values associated with it
* in the query, hence the fieldList. However the first entry is representative of the field for most purposes.
*
* @param executionContext contains the top level execution parameters
* @param parameters contains the parameters holding the fields to be executed and source object
*
* @return a promise to an {@link ExecutionResult}
*
* @throws NonNullableFieldWasNullException in the future if a non null field resolves to a null value
*/
protected CompletableFuture<ExecutionResult> resolveField(ExecutionContext executionContext, ExecutionStrategyParameters parameters) {
return resolveFieldWithInfo(executionContext, parameters).thenCompose(FieldValueInfo::getFieldValue);
}
/**
* Called to fetch a value for a field and its extra runtime info and resolve it further in terms of the graphql query. This will call
* #fetchField followed by #completeField and the completed {@link graphql.execution.FieldValueInfo} is returned.
* <p>
* An execution strategy can iterate the fields to be executed and call this method for each one
* <p>
* Graphql fragments mean that for any give logical field can have one or more {@link Field} values associated with it
* in the query, hence the fieldList. However the first entry is representative of the field for most purposes.
*
* @param executionContext contains the top level execution parameters
* @param parameters contains the parameters holding the fields to be executed and source object
*
* @return a promise to a {@link FieldValueInfo}
*
* @throws NonNullableFieldWasNullException in the {@link FieldValueInfo#getFieldValue()} future if a non null field resolves to a null value
*/
protected CompletableFuture<FieldValueInfo> resolveFieldWithInfo(ExecutionContext executionContext, ExecutionStrategyParameters parameters) {
GraphQLFieldDefinition fieldDef = getFieldDef(executionContext, parameters, parameters.getField().getSingleField());
Supplier<ExecutionStepInfo> executionStepInfo = FpKit.intraThreadMemoize(() -> createExecutionStepInfo(executionContext, parameters, fieldDef, null));
Instrumentation instrumentation = executionContext.getInstrumentation();
InstrumentationContext<ExecutionResult> fieldCtx = nonNullCtx(instrumentation.beginField(
new InstrumentationFieldParameters(executionContext, executionStepInfo), executionContext.getInstrumentationState()
));
CompletableFuture<FetchedValue> fetchFieldFuture = fetchField(executionContext, parameters);
CompletableFuture<FieldValueInfo> result = fetchFieldFuture.thenApply((fetchedValue) ->
completeField(executionContext, parameters, fetchedValue));
CompletableFuture<ExecutionResult> executionResultFuture = result.thenCompose(FieldValueInfo::getFieldValue);
fieldCtx.onDispatched(executionResultFuture);
executionResultFuture.whenComplete(fieldCtx::onCompleted);
return result;
}
/**
* Called to fetch a value for a field from the {@link DataFetcher} associated with the field
* {@link GraphQLFieldDefinition}.
* <p>
* Graphql fragments mean that for any give logical field can have one or more {@link Field} values associated with it
* in the query, hence the fieldList. However the first entry is representative of the field for most purposes.
*
* @param executionContext contains the top level execution parameters
* @param parameters contains the parameters holding the fields to be executed and source object
*
* @return a promise to a fetched object
*
* @throws NonNullableFieldWasNullException in the future if a non null field resolves to a null value
*/
protected CompletableFuture<FetchedValue> fetchField(ExecutionContext executionContext, ExecutionStrategyParameters parameters) {
MergedField field = parameters.getField();
GraphQLObjectType parentType = (GraphQLObjectType) parameters.getExecutionStepInfo().getUnwrappedNonNullType();
GraphQLFieldDefinition fieldDef = getFieldDef(executionContext.getGraphQLSchema(), parentType, field.getSingleField());
GraphQLCodeRegistry codeRegistry = executionContext.getGraphQLSchema().getCodeRegistry();
// if the DF (like PropertyDataFetcher) does not use the arguments or execution step info then dont build any
Supplier<DataFetchingEnvironment> dataFetchingEnvironment = FpKit.intraThreadMemoize(() -> {
Supplier<ExecutionStepInfo> executionStepInfo = FpKit.intraThreadMemoize(
() -> createExecutionStepInfo(executionContext, parameters, fieldDef, parentType));
Supplier<Map<String, Object>> argumentValues = () -> executionStepInfo.get().getArguments();
Supplier<ExecutableNormalizedField> normalizedFieldSupplier = getNormalizedField(executionContext, parameters, executionStepInfo);
// DataFetchingFieldSelectionSet and QueryDirectives is a supplier of sorts - eg a lazy pattern
DataFetchingFieldSelectionSet fieldCollector = DataFetchingFieldSelectionSetImpl.newCollector(executionContext.getGraphQLSchema(), fieldDef.getType(), normalizedFieldSupplier);
QueryDirectives queryDirectives = new QueryDirectivesImpl(field,
executionContext.getGraphQLSchema(),
executionContext.getCoercedVariables().toMap(),
executionContext.getGraphQLContext(),
executionContext.getLocale());
return newDataFetchingEnvironment(executionContext)
.source(parameters.getSource())
.localContext(parameters.getLocalContext())
.arguments(argumentValues)
.fieldDefinition(fieldDef)
.mergedField(parameters.getField())
.fieldType(fieldDef.getType())
.executionStepInfo(executionStepInfo)
.parentType(parentType)
.selectionSet(fieldCollector)
.queryDirectives(queryDirectives)
.build();
});
DataFetcher<?> dataFetcher = codeRegistry.getDataFetcher(parentType, fieldDef);
Instrumentation instrumentation = executionContext.getInstrumentation();
InstrumentationFieldFetchParameters instrumentationFieldFetchParams = new InstrumentationFieldFetchParameters(executionContext, dataFetchingEnvironment, parameters, dataFetcher instanceof TrivialDataFetcher);
InstrumentationContext<Object> fetchCtx = nonNullCtx(instrumentation.beginFieldFetch(instrumentationFieldFetchParams,
executionContext.getInstrumentationState())
);
dataFetcher = instrumentation.instrumentDataFetcher(dataFetcher, instrumentationFieldFetchParams, executionContext.getInstrumentationState());
CompletableFuture<Object> fetchedValue = invokeDataFetcher(executionContext, parameters, fieldDef, dataFetchingEnvironment, dataFetcher);
fetchCtx.onDispatched(fetchedValue);
return fetchedValue
.handle((result, exception) -> {
fetchCtx.onCompleted(result, exception);
if (exception != null) {
return handleFetchingException(dataFetchingEnvironment.get(), exception);
} else {
// we can simply return the fetched value CF and avoid a allocation
return fetchedValue;
}
})
.thenCompose(Function.identity())
.thenApply(result -> unboxPossibleDataFetcherResult(executionContext, parameters, result));
}
private CompletableFuture<Object> invokeDataFetcher(ExecutionContext executionContext, ExecutionStrategyParameters parameters, GraphQLFieldDefinition fieldDef, Supplier<DataFetchingEnvironment> dataFetchingEnvironment, DataFetcher<?> dataFetcher) {
CompletableFuture<Object> fetchedValue;
try {
Object fetchedValueRaw;
if (dataFetcher instanceof LightDataFetcher) {
fetchedValueRaw = ((LightDataFetcher<?>) dataFetcher).get(fieldDef, parameters.getSource(), dataFetchingEnvironment);
} else {
fetchedValueRaw = dataFetcher.get(dataFetchingEnvironment.get());
}
fetchedValue = Async.toCompletableFuture(fetchedValueRaw);
} catch (Exception e) {
if (logNotSafe.isDebugEnabled()) {
logNotSafe.debug(String.format("'%s', field '%s' fetch threw exception", executionContext.getExecutionId(), parameters.getPath()), e);
}
fetchedValue = Async.exceptionallyCompletedFuture(e);
}
return fetchedValue;
}
protected Supplier<ExecutableNormalizedField> getNormalizedField(ExecutionContext executionContext, ExecutionStrategyParameters parameters, Supplier<ExecutionStepInfo> executionStepInfo) {
Supplier<ExecutableNormalizedOperation> normalizedQuery = executionContext.getNormalizedQueryTree();
return () -> normalizedQuery.get().getNormalizedField(parameters.getField(), executionStepInfo.get().getObjectType(), executionStepInfo.get().getPath());
}
protected FetchedValue unboxPossibleDataFetcherResult(ExecutionContext executionContext,
ExecutionStrategyParameters parameters,
Object result) {
if (result instanceof DataFetcherResult) {
DataFetcherResult<?> dataFetcherResult = (DataFetcherResult<?>) result;
executionContext.addErrors(dataFetcherResult.getErrors());
addExtensionsIfPresent(executionContext, dataFetcherResult);
Object localContext = dataFetcherResult.getLocalContext();
if (localContext == null) {
// if the field returns nothing then they get the context of their parent field
localContext = parameters.getLocalContext();
}
return FetchedValue.newFetchedValue()
.fetchedValue(executionContext.getValueUnboxer().unbox(dataFetcherResult.getData()))
.rawFetchedValue(dataFetcherResult.getData())
.errors(dataFetcherResult.getErrors())
.localContext(localContext)
.build();
} else {
return FetchedValue.newFetchedValue()
.fetchedValue(executionContext.getValueUnboxer().unbox(result))
.rawFetchedValue(result)
.localContext(parameters.getLocalContext())
.build();
}
}
private void addExtensionsIfPresent(ExecutionContext executionContext, DataFetcherResult<?> dataFetcherResult) {
Map<Object, Object> extensions = dataFetcherResult.getExtensions();
if (extensions != null) {
ExtensionsBuilder extensionsBuilder = executionContext.getGraphQLContext().get(ExtensionsBuilder.class);
if (extensionsBuilder != null) {
extensionsBuilder.addValues(extensions);
}
}
}
protected <T> CompletableFuture<T> handleFetchingException(
DataFetchingEnvironment environment,
Throwable e) {
DataFetcherExceptionHandlerParameters handlerParameters = DataFetcherExceptionHandlerParameters.newExceptionParameters()
.dataFetchingEnvironment(environment)
.exception(e)
.build();
try {
return asyncHandleException(dataFetcherExceptionHandler, handlerParameters);
} catch (Exception handlerException) {
handlerParameters = DataFetcherExceptionHandlerParameters.newExceptionParameters()
.dataFetchingEnvironment(environment)
.exception(handlerException)
.build();
return asyncHandleException(new SimpleDataFetcherExceptionHandler(), handlerParameters);
}
}
private <T> CompletableFuture<T> asyncHandleException(DataFetcherExceptionHandler handler, DataFetcherExceptionHandlerParameters handlerParameters) {
//noinspection unchecked
return handler.handleException(handlerParameters).thenApply(
handlerResult -> (T) DataFetcherResult.<FetchedValue>newResult().errors(handlerResult.getErrors()).build()
);
}
/**
* Called to complete a field based on the type of the field.
* <p>
* If the field is a scalar type, then it will be coerced and returned. However if the field type is an complex object type, then
* the execution strategy will be called recursively again to execute the fields of that type before returning.
* <p>
* Graphql fragments mean that for any give logical field can have one or more {@link Field} values associated with it
* in the query, hence the fieldList. However the first entry is representative of the field for most purposes.
*
* @param executionContext contains the top level execution parameters
* @param parameters contains the parameters holding the fields to be executed and source object
* @param fetchedValue the fetched raw value
*
* @return a {@link FieldValueInfo}
*
* @throws NonNullableFieldWasNullException in the {@link FieldValueInfo#getFieldValue()} future if a non null field resolves to a null value
*/
protected FieldValueInfo completeField(ExecutionContext executionContext, ExecutionStrategyParameters parameters, FetchedValue fetchedValue) {
Field field = parameters.getField().getSingleField();
GraphQLObjectType parentType = (GraphQLObjectType) parameters.getExecutionStepInfo().getUnwrappedNonNullType();
GraphQLFieldDefinition fieldDef = getFieldDef(executionContext.getGraphQLSchema(), parentType, field);
ExecutionStepInfo executionStepInfo = createExecutionStepInfo(executionContext, parameters, fieldDef, parentType);
Instrumentation instrumentation = executionContext.getInstrumentation();
InstrumentationFieldCompleteParameters instrumentationParams = new InstrumentationFieldCompleteParameters(executionContext, parameters, () -> executionStepInfo, fetchedValue);
InstrumentationContext<ExecutionResult> ctxCompleteField = nonNullCtx(instrumentation.beginFieldComplete(
instrumentationParams, executionContext.getInstrumentationState()
));
NonNullableFieldValidator nonNullableFieldValidator = new NonNullableFieldValidator(executionContext, executionStepInfo);
ExecutionStrategyParameters newParameters = parameters.transform(builder ->
builder.executionStepInfo(executionStepInfo)
.source(fetchedValue.getFetchedValue())
.localContext(fetchedValue.getLocalContext())
.nonNullFieldValidator(nonNullableFieldValidator)
);
if (log.isDebugEnabled()) {
log.debug("'{}' completing field '{}'...", executionContext.getExecutionId(), executionStepInfo.getPath());
}
FieldValueInfo fieldValueInfo = completeValue(executionContext, newParameters);
CompletableFuture<ExecutionResult> executionResultFuture = fieldValueInfo.getFieldValue();
ctxCompleteField.onDispatched(executionResultFuture);
executionResultFuture.whenComplete(ctxCompleteField::onCompleted);
return fieldValueInfo;
}
/**
* Called to complete a value for a field based on the type of the field.
* <p>
* If the field is a scalar type, then it will be coerced and returned. However if the field type is an complex object type, then
* the execution strategy will be called recursively again to execute the fields of that type before returning.
* <p>
* Graphql fragments mean that for any give logical field can have one or more {@link Field} values associated with it
* in the query, hence the fieldList. However the first entry is representative of the field for most purposes.
*
* @param executionContext contains the top level execution parameters
* @param parameters contains the parameters holding the fields to be executed and source object
*
* @return a {@link FieldValueInfo}
*
* @throws NonNullableFieldWasNullException if a non null field resolves to a null value
*/
protected FieldValueInfo completeValue(ExecutionContext executionContext, ExecutionStrategyParameters parameters) throws NonNullableFieldWasNullException {
ExecutionStepInfo executionStepInfo = parameters.getExecutionStepInfo();
Object result = executionContext.getValueUnboxer().unbox(parameters.getSource());
GraphQLType fieldType = executionStepInfo.getUnwrappedNonNullType();
CompletableFuture<ExecutionResult> fieldValue;
if (result == null) {
return getFieldValueInfoForNull(executionContext, parameters);
} else if (isList(fieldType)) {
return completeValueForList(executionContext, parameters, result);
} else if (isScalar(fieldType)) {
fieldValue = completeValueForScalar(executionContext, parameters, (GraphQLScalarType) fieldType, result);
return FieldValueInfo.newFieldValueInfo(SCALAR).fieldValue(fieldValue).build();
} else if (isEnum(fieldType)) {
fieldValue = completeValueForEnum(executionContext, parameters, (GraphQLEnumType) fieldType, result);
return FieldValueInfo.newFieldValueInfo(ENUM).fieldValue(fieldValue).build();
}
// when we are here, we have a complex type: Interface, Union or Object
// and we must go deeper
//
GraphQLObjectType resolvedObjectType;
try {
resolvedObjectType = resolveType(executionContext, parameters, fieldType);
fieldValue = completeValueForObject(executionContext, parameters, resolvedObjectType, result);
} catch (UnresolvedTypeException ex) {
// consider the result to be null and add the error on the context
handleUnresolvedTypeProblem(executionContext, parameters, ex);
// complete field as null, validating it is nullable
return getFieldValueInfoForNull(executionContext, parameters);
}
return FieldValueInfo.newFieldValueInfo(OBJECT).fieldValue(fieldValue).build();
}
private void handleUnresolvedTypeProblem(ExecutionContext context, ExecutionStrategyParameters parameters, UnresolvedTypeException e) {
UnresolvedTypeError error = new UnresolvedTypeError(parameters.getPath(), parameters.getExecutionStepInfo(), e);
logNotSafe.warn(error.getMessage(), e);
context.addError(error);
}
/**
* Called to complete a null value.
*
* @param executionContext contains the top level execution parameters
* @param parameters contains the parameters holding the fields to be executed and source object
*
* @return a {@link FieldValueInfo}
*
* @throws NonNullableFieldWasNullException if a non null field resolves to a null value
*/
private FieldValueInfo getFieldValueInfoForNull(ExecutionContext executionContext, ExecutionStrategyParameters parameters) {
CompletableFuture<ExecutionResult> fieldValue = completeValueForNull(executionContext, parameters);
return FieldValueInfo.newFieldValueInfo(NULL).fieldValue(fieldValue).build();
}
protected CompletableFuture<ExecutionResult> completeValueForNull(ExecutionContext executionContext, ExecutionStrategyParameters parameters) {
return Async.tryCatch(() -> {
Object nullValue = parameters.getNonNullFieldValidator().validate(parameters.getPath(), null);
return completedFuture(new ExecutionResultImpl(nullValue, executionContext.getErrors()));
});
}
/**
* Called to complete a list of value for a field based on a list type. This iterates the values and calls
* {@link #completeValue(ExecutionContext, ExecutionStrategyParameters)} for each value.
*
* @param executionContext contains the top level execution parameters
* @param parameters contains the parameters holding the fields to be executed and source object
* @param result the result to complete, raw result
*
* @return a {@link FieldValueInfo}
*/
protected FieldValueInfo completeValueForList(ExecutionContext executionContext, ExecutionStrategyParameters parameters, Object result) {
Iterable<Object> resultIterable = toIterable(executionContext, parameters, result);
try {
resultIterable = parameters.getNonNullFieldValidator().validate(parameters.getPath(), resultIterable);
} catch (NonNullableFieldWasNullException e) {
return FieldValueInfo.newFieldValueInfo(LIST).fieldValue(exceptionallyCompletedFuture(e)).build();
}
if (resultIterable == null) {
return FieldValueInfo.newFieldValueInfo(LIST).fieldValue(completedFuture(new ExecutionResultImpl(null, executionContext.getErrors()))).build();
}
return completeValueForList(executionContext, parameters, resultIterable);
}
/**
* Called to complete a list of value for a field based on a list type. This iterates the values and calls
* {@link #completeValue(ExecutionContext, ExecutionStrategyParameters)} for each value.
*
* @param executionContext contains the top level execution parameters
* @param parameters contains the parameters holding the fields to be executed and source object
* @param iterableValues the values to complete, can't be null
*
* @return a {@link FieldValueInfo}
*/
protected FieldValueInfo completeValueForList(ExecutionContext executionContext, ExecutionStrategyParameters parameters, Iterable<Object> iterableValues) {
OptionalInt size = FpKit.toSize(iterableValues);
ExecutionStepInfo executionStepInfo = parameters.getExecutionStepInfo();
InstrumentationFieldCompleteParameters instrumentationParams = new InstrumentationFieldCompleteParameters(executionContext, parameters, () -> executionStepInfo, iterableValues);
Instrumentation instrumentation = executionContext.getInstrumentation();
InstrumentationContext<ExecutionResult> completeListCtx = nonNullCtx(instrumentation.beginFieldListComplete(
instrumentationParams, executionContext.getInstrumentationState()
));
List<FieldValueInfo> fieldValueInfos = new ArrayList<>(size.orElse(1));
int index = 0;
for (Object item : iterableValues) {
ResultPath indexedPath = parameters.getPath().segment(index);
ExecutionStepInfo stepInfoForListElement = executionStepInfoFactory.newExecutionStepInfoForListElement(executionStepInfo, indexedPath);
NonNullableFieldValidator nonNullableFieldValidator = new NonNullableFieldValidator(executionContext, stepInfoForListElement);
FetchedValue value = unboxPossibleDataFetcherResult(executionContext, parameters, item);
ExecutionStrategyParameters newParameters = parameters.transform(builder ->
builder.executionStepInfo(stepInfoForListElement)
.nonNullFieldValidator(nonNullableFieldValidator)
.localContext(value.getLocalContext())
.path(indexedPath)
.source(value.getFetchedValue())
);
fieldValueInfos.add(completeValue(executionContext, newParameters));
index++;
}
CompletableFuture<List<ExecutionResult>> resultsFuture = Async.each(fieldValueInfos, FieldValueInfo::getFieldValue);
CompletableFuture<ExecutionResult> overallResult = new CompletableFuture<>();
completeListCtx.onDispatched(overallResult);
resultsFuture.whenComplete((results, exception) -> {
if (exception != null) {
ExecutionResult executionResult = handleNonNullException(executionContext, overallResult, exception);
completeListCtx.onCompleted(executionResult, exception);
return;
}
List<Object> completedResults = new ArrayList<>(results.size());
for (ExecutionResult completedValue : results) {
completedResults.add(completedValue.getData());
}
ExecutionResultImpl executionResult = new ExecutionResultImpl(completedResults, executionContext.getErrors());
overallResult.complete(executionResult);
});
overallResult.whenComplete(completeListCtx::onCompleted);
return FieldValueInfo.newFieldValueInfo(LIST)
.fieldValue(overallResult)
.fieldValueInfos(fieldValueInfos)
.build();
}
/**
* Called to turn an object into a scalar value according to the {@link GraphQLScalarType} by asking that scalar type to coerce the object
* into a valid value
*
* @param executionContext contains the top level execution parameters
* @param parameters contains the parameters holding the fields to be executed and source object
* @param scalarType the type of the scalar
* @param result the result to be coerced
*
* @return a promise to an {@link ExecutionResult}
*/
protected CompletableFuture<ExecutionResult> completeValueForScalar(ExecutionContext executionContext, ExecutionStrategyParameters parameters, GraphQLScalarType scalarType, Object result) {
Object serialized;
try {
serialized = scalarType.getCoercing().serialize(result, executionContext.getGraphQLContext(), executionContext.getLocale());
} catch (CoercingSerializeException e) {
serialized = handleCoercionProblem(executionContext, parameters, e);
}
try {
serialized = parameters.getNonNullFieldValidator().validate(parameters.getPath(), serialized);
} catch (NonNullableFieldWasNullException e) {
return exceptionallyCompletedFuture(e);
}
return completedFuture(new ExecutionResultImpl(serialized, executionContext.getErrors()));
}
/**
* Called to turn an object into a enum value according to the {@link GraphQLEnumType} by asking that enum type to coerce the object into a valid value
*
* @param executionContext contains the top level execution parameters
* @param parameters contains the parameters holding the fields to be executed and source object
* @param enumType the type of the enum
* @param result the result to be coerced
*
* @return a promise to an {@link ExecutionResult}
*/
protected CompletableFuture<ExecutionResult> completeValueForEnum(ExecutionContext executionContext, ExecutionStrategyParameters parameters, GraphQLEnumType enumType, Object result) {
Object serialized;
try {
serialized = enumType.serialize(result, executionContext.getGraphQLContext(), executionContext.getLocale());
} catch (CoercingSerializeException e) {
serialized = handleCoercionProblem(executionContext, parameters, e);
}
try {
serialized = parameters.getNonNullFieldValidator().validate(parameters.getPath(), serialized);
} catch (NonNullableFieldWasNullException e) {
return exceptionallyCompletedFuture(e);
}
return completedFuture(new ExecutionResultImpl(serialized, executionContext.getErrors()));
}
/**
* Called to turn a java object value into an graphql object value
*
* @param executionContext contains the top level execution parameters
* @param parameters contains the parameters holding the fields to be executed and source object
* @param resolvedObjectType the resolved object type
* @param result the result to be coerced
*
* @return a promise to an {@link ExecutionResult}
*/
protected CompletableFuture<ExecutionResult> completeValueForObject(ExecutionContext executionContext, ExecutionStrategyParameters parameters, GraphQLObjectType resolvedObjectType, Object result) {
ExecutionStepInfo executionStepInfo = parameters.getExecutionStepInfo();
FieldCollectorParameters collectorParameters = newParameters()
.schema(executionContext.getGraphQLSchema())
.objectType(resolvedObjectType)
.fragments(executionContext.getFragmentsByName())
.variables(executionContext.getCoercedVariables().toMap())
.build();
MergedSelectionSet subFields = fieldCollector.collectFields(collectorParameters, parameters.getField());
ExecutionStepInfo newExecutionStepInfo = executionStepInfo.changeTypeWithPreservedNonNull(resolvedObjectType);
NonNullableFieldValidator nonNullableFieldValidator = new NonNullableFieldValidator(executionContext, newExecutionStepInfo);
ExecutionStrategyParameters newParameters = parameters.transform(builder ->
builder.executionStepInfo(newExecutionStepInfo)
.fields(subFields)
.nonNullFieldValidator(nonNullableFieldValidator)
.source(result)
);
// Calling this from the executionContext to ensure we shift back from mutation strategy to the query strategy.
return executionContext.getQueryStrategy().execute(executionContext, newParameters);
}
@SuppressWarnings("SameReturnValue")
private Object handleCoercionProblem(ExecutionContext context, ExecutionStrategyParameters parameters, CoercingSerializeException e) {
SerializationError error = new SerializationError(parameters.getPath(), e);
logNotSafe.warn(error.getMessage(), e);
context.addError(error);
return null;
}
protected GraphQLObjectType resolveType(ExecutionContext executionContext, ExecutionStrategyParameters parameters, GraphQLType fieldType) {
// we can avoid a method call and type resolver environment allocation if we know it's an object type
if (fieldType instanceof GraphQLObjectType) {
return (GraphQLObjectType) fieldType;
}
return resolvedType.resolveType(executionContext, parameters.getField(), parameters.getSource(), parameters.getExecutionStepInfo(), fieldType, parameters.getLocalContext());
}
protected Iterable<Object> toIterable(ExecutionContext context, ExecutionStrategyParameters parameters, Object result) {
if (FpKit.isIterable(result)) {
return FpKit.toIterable(result);
}
handleTypeMismatchProblem(context, parameters, result);
return null;
}
private void handleTypeMismatchProblem(ExecutionContext context, ExecutionStrategyParameters parameters, Object result) {
TypeMismatchError error = new TypeMismatchError(parameters.getPath(), parameters.getExecutionStepInfo().getUnwrappedNonNullType());
logNotSafe.warn("{} got {}", error.getMessage(), result.getClass());
context.addError(error);
}
/**
* Called to discover the field definition give the current parameters and the AST {@link Field}
*
* @param executionContext contains the top level execution parameters
* @param parameters contains the parameters holding the fields to be executed and source object
* @param field the field to find the definition of
*
* @return a {@link GraphQLFieldDefinition}
*/
protected GraphQLFieldDefinition getFieldDef(ExecutionContext executionContext, ExecutionStrategyParameters parameters, Field field) {
GraphQLObjectType parentType = (GraphQLObjectType) parameters.getExecutionStepInfo().getUnwrappedNonNullType();
return getFieldDef(executionContext.getGraphQLSchema(), parentType, field);
}
/**
* Called to discover the field definition give the current parameters and the AST {@link Field}
*
* @param schema the schema in play
* @param parentType the parent type of the field
* @param field the field to find the definition of
*
* @return a {@link GraphQLFieldDefinition}
*/
protected GraphQLFieldDefinition getFieldDef(GraphQLSchema schema, GraphQLObjectType parentType, Field field) {
return Introspection.getFieldDef(schema, parentType, field.getName());
}
/**
* See (<a href="https://spec.graphql.org/October2021/#sec-Errors-and-Non-Nullability">...</a>),
* <p>
* If a non nullable child field type actually resolves to a null value and the parent type is nullable
* then the parent must in fact become null
* so we use exceptions to indicate this special case. However if the parent is in fact a non nullable type
* itself then we need to bubble that upwards again until we get to the root in which case the result
* is meant to be null.
*
* @param e this indicates that a null value was returned for a non null field, which needs to cause the parent field
* to become null OR continue on as an exception
*
* @throws NonNullableFieldWasNullException if a non null field resolves to a null value
*/
protected void assertNonNullFieldPrecondition(NonNullableFieldWasNullException e) throws NonNullableFieldWasNullException {
ExecutionStepInfo executionStepInfo = e.getExecutionStepInfo();
if (executionStepInfo.hasParent() && executionStepInfo.getParent().isNonNullType()) {
throw new NonNullableFieldWasNullException(e);
}
}
protected void assertNonNullFieldPrecondition(NonNullableFieldWasNullException e, CompletableFuture<?> completableFuture) throws NonNullableFieldWasNullException {
ExecutionStepInfo executionStepInfo = e.getExecutionStepInfo();
if (executionStepInfo.hasParent() && executionStepInfo.getParent().isNonNullType()) {
completableFuture.completeExceptionally(new NonNullableFieldWasNullException(e));
}
}
protected ExecutionResult handleNonNullException(ExecutionContext executionContext, CompletableFuture<ExecutionResult> result, Throwable e) {
ExecutionResult executionResult = null;
List<GraphQLError> errors = ImmutableList.copyOf(executionContext.getErrors());
Throwable underlyingException = e;
if (e instanceof CompletionException) {
underlyingException = e.getCause();
}
if (underlyingException instanceof NonNullableFieldWasNullException) {
assertNonNullFieldPrecondition((NonNullableFieldWasNullException) underlyingException, result);
if (!result.isDone()) {
executionResult = new ExecutionResultImpl(null, errors);
result.complete(executionResult);
}
} else if (underlyingException instanceof AbortExecutionException) {
AbortExecutionException abortException = (AbortExecutionException) underlyingException;
executionResult = abortException.toExecutionResult();
result.complete(executionResult);
} else {
result.completeExceptionally(e);
}
return executionResult;
}
/**
* Builds the type info hierarchy for the current field
*
* @param executionContext the execution context in play
* @param parameters contains the parameters holding the fields to be executed and source object
* @param fieldDefinition the field definition to build type info for
* @param fieldContainer the field container
*
* @return a new type info
*/
protected ExecutionStepInfo createExecutionStepInfo(ExecutionContext executionContext,
ExecutionStrategyParameters parameters,
GraphQLFieldDefinition fieldDefinition,
GraphQLObjectType fieldContainer) {
MergedField field = parameters.getField();
ExecutionStepInfo parentStepInfo = parameters.getExecutionStepInfo();
GraphQLOutputType fieldType = fieldDefinition.getType();
List<GraphQLArgument> fieldArgDefs = fieldDefinition.getArguments();
Supplier<Map<String, Object>> argumentValues = ImmutableKit::emptyMap;
//
// no need to create args at all if there are none on the field def
//
if (!fieldArgDefs.isEmpty()) {
List<Argument> fieldArgs = field.getArguments();
GraphQLCodeRegistry codeRegistry = executionContext.getGraphQLSchema().getCodeRegistry();
Supplier<Map<String, Object>> argValuesSupplier = () -> ValuesResolver.getArgumentValues(codeRegistry,
fieldArgDefs,
fieldArgs,
executionContext.getCoercedVariables(),
executionContext.getGraphQLContext(),
executionContext.getLocale());
argumentValues = FpKit.intraThreadMemoize(argValuesSupplier);
}
return newExecutionStepInfo()
.type(fieldType)
.fieldDefinition(fieldDefinition)
.fieldContainer(fieldContainer)
.field(field)
.path(parameters.getPath())
.parentInfo(parentStepInfo)
.arguments(argumentValues)
.build();
}
@Internal
public static String mkNameForPath(Field currentField) {
return mkNameForPath(Collections.singletonList(currentField));
}
@Internal
public static String mkNameForPath(MergedField mergedField) {
return mkNameForPath(mergedField.getFields());
}
@Internal
public static String mkNameForPath(List<Field> currentField) {
Field field = currentField.get(0);
return field.getResultKey();
}
}