graphql.kickstart.tools.resolver.MethodFieldResolver.kt Maven / Gradle / Ivy
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Tools to help map a GraphQL schema to existing Java objects.
package graphql.kickstart.tools.resolver
import com.fasterxml.jackson.core.type.TypeReference
import graphql.TrivialDataFetcher
import graphql.kickstart.tools.*
import graphql.kickstart.tools.SchemaParserOptions.GenericWrapper
import graphql.kickstart.tools.util.JavaType
import graphql.kickstart.tools.util.coroutineScope
import graphql.kickstart.tools.util.isTrivialDataFetcher
import graphql.kickstart.tools.util.unwrap
import graphql.language.*
import graphql.schema.DataFetcher
import graphql.schema.DataFetchingEnvironment
import graphql.schema.GraphQLTypeUtil.isScalar
import kotlinx.coroutines.future.future
import java.lang.reflect.Method
import java.util.*
import kotlin.coroutines.intrinsics.suspendCoroutineUninterceptedOrReturn
import kotlin.reflect.full.valueParameters
import kotlin.reflect.jvm.javaType
import kotlin.reflect.jvm.kotlinFunction
/**
* @author Andrew Potter
*/
internal class MethodFieldResolver(
field: FieldDefinition,
search: FieldResolverScanner.Search,
options: SchemaParserOptions,
val method: Method
) : FieldResolver(field, search, options, search.type) {
private val additionalLastArgument =
try {
method.kotlinFunction?.valueParameters?.size ?: method.parameterCount == (field.inputValueDefinitions.size + getIndexOffset() + 1)
} catch (e: InternalError) {
method.parameterCount == (field.inputValueDefinitions.size + getIndexOffset() + 1)
}
override fun createDataFetcher(): DataFetcher<*> {
val args = mutableListOf()
val mapper = options.objectMapperProvider.provide(field)
// Add source argument if this is a resolver (but not a root resolver)
if (this.search.requiredFirstParameterType != null) {
val expectedType = this.search.requiredFirstParameterType
args.add { environment ->
val source = environment.getSource()
if (!expectedType.isAssignableFrom(source.javaClass)) {
throw ResolverError("Source type (${source.javaClass.name}) is not expected type (${expectedType.name})!")
}
source
}
}
// Add an argument for each argument defined in the GraphQL schema
this.field.inputValueDefinitions.forEachIndexed { index, definition ->
val parameterType = this.getMethodParameterType(index)
?.apply { genericType.getRawClass(this) }
?: throw ResolverError("Missing method type at position ${this.getJavaMethodParameterIndex(index)}, this is most likely a bug with graphql-java-tools")
val isNonNull = definition.type is NonNullType
val isOptional = this.genericType.getRawClass(parameterType) == Optional::class.java
args.add { environment ->
val argumentPresent = environment.arguments.containsKey(definition.name)
if (!argumentPresent && isNonNull) {
throw ResolverError("Missing required argument with name '${definition.name}', this is most likely a bug with graphql-java-tools")
}
val value = environment.arguments[definition.name]
if (value == null && isOptional) {
if (options.inputArgumentOptionalDetectOmission && !environment.containsArgument(definition.name)) {
return@add null
}
return@add Optional.empty()
}
if (value == null || shouldValueBeConverted(value, definition, parameterType, environment)) {
return@add mapper.convertValue(value, object : TypeReference() {
override fun getType() = parameterType
})
}
return@add value
}
}
// Add DataFetchingEnvironment/Context argument
if (this.additionalLastArgument) {
when (this.method.parameterTypes.last()) {
null -> throw ResolverError("Expected at least one argument but got none, this is most likely a bug with graphql-java-tools")
options.contextClass -> args.add { environment -> environment.getContext() }
else -> args.add { environment -> environment }
}
}
return if (args.isEmpty() && isTrivialDataFetcher(this.method)) {
TrivialMethodFieldResolverDataFetcher(getSourceResolver(), this.method, args, options)
} else {
MethodFieldResolverDataFetcher(getSourceResolver(), this.method, args, options)
}
}
private fun shouldValueBeConverted(value: Any, definition: InputValueDefinition, parameterType: JavaType, environment: DataFetchingEnvironment): Boolean {
return !parameterType.unwrap().isAssignableFrom(value.javaClass) || !isConcreteScalarType(environment, definition.type, parameterType)
}
/**
* A concrete scalar type is a scalar type where values always coerce to the same Java type. The ID scalar type is not concrete
* because values can be coerced to multiple different Java types (eg. String, Long, UUID). All values of a non-concrete scalar
* type must be converted to the target method parameter type.
*/
private fun isConcreteScalarType(environment: DataFetchingEnvironment, type: Type<*>, genericParameterType: JavaType): Boolean {
return when (type) {
is ListType -> List::class.java.isAssignableFrom(this.genericType.getRawClass(genericParameterType))
&& isConcreteScalarType(environment, type.type, this.genericType.unwrapGenericType(genericParameterType))
is TypeName -> environment.graphQLSchema?.getType(type.name)?.let { isScalar(it) && type.name != "ID" }
?: false
is NonNullType -> isConcreteScalarType(environment, type.type, genericParameterType)
else -> false
}
}
override fun scanForMatches(): List {
val unwrappedGenericType = genericType.unwrapGenericType(try {
method.kotlinFunction?.returnType?.javaType ?: method.genericReturnType
} catch (e: InternalError) {
method.genericReturnType
})
val returnValueMatch = TypeClassMatcher.PotentialMatch.returnValue(field.type, unwrappedGenericType, genericType, SchemaClassScanner.ReturnValueReference(method))
return field.inputValueDefinitions.mapIndexed { i, inputDefinition ->
TypeClassMatcher.PotentialMatch.parameterType(inputDefinition.type, getMethodParameterType(i)!!, genericType, SchemaClassScanner.MethodParameterReference(method, i))
} + listOf(returnValueMatch)
}
private fun getIndexOffset(): Int {
return if (resolverInfo is DataClassTypeResolverInfo && !method.declaringClass.isAssignableFrom(resolverInfo.dataClassType)) {
1
} else {
0
}
}
private fun getJavaMethodParameterIndex(index: Int) = index + getIndexOffset()
private fun getMethodParameterType(index: Int): JavaType? {
val methodIndex = getJavaMethodParameterIndex(index)
val parameters = method.parameterTypes
return if (parameters.size > methodIndex) {
method.genericParameterTypes[methodIndex]
} else {
null
}
}
override fun toString() = "MethodFieldResolver{method=$method}"
}
internal open class MethodFieldResolverDataFetcher(
private val sourceResolver: SourceResolver,
method: Method,
private val args: List,
private val options: SchemaParserOptions
) : DataFetcher {
private val resolverMethod = method
private val isSuspendFunction = try {
method.kotlinFunction?.isSuspend == true
} catch (e: InternalError) {
false
}
private class CompareGenericWrappers {
companion object : Comparator {
override fun compare(w1: GenericWrapper, w2: GenericWrapper): Int = when {
w1.type.isAssignableFrom(w2.type) -> 1
else -> -1
}
}
}
override fun get(environment: DataFetchingEnvironment): Any? {
val source = sourceResolver(environment)
val args = this.args.map { it(environment) }.toTypedArray()
return if (isSuspendFunction) {
environment.coroutineScope().future(options.coroutineContextProvider.provide()) {
invokeSuspend(source, resolverMethod, args)?.transformWithGenericWrapper(environment)
}
} else {
invoke(resolverMethod, source, args)?.transformWithGenericWrapper(environment)
}
}
private fun Any.transformWithGenericWrapper(environment: DataFetchingEnvironment): Any? {
return options.genericWrappers
.asSequence()
.filter { it.type.isInstance(this) }
.sortedWith(CompareGenericWrappers)
.firstOrNull()
?.transformer?.invoke(this, environment) ?: this
}
/**
* Function that returns the object used to fetch the data.
* It can be a DataFetcher or an entity.
*/
@Suppress("unused")
open fun getWrappedFetchingObject(environment: DataFetchingEnvironment): Any {
return sourceResolver(environment)
}
}
internal class TrivialMethodFieldResolverDataFetcher(
sourceResolver: SourceResolver,
method: Method,
args: List,
options: SchemaParserOptions
) : MethodFieldResolverDataFetcher(sourceResolver, method, args, options),
TrivialDataFetcher // just to mark it for tracing and optimizations
private suspend inline fun invokeSuspend(target: Any, resolverMethod: Method, args: Array): Any? {
return suspendCoroutineUninterceptedOrReturn { continuation ->
invoke(resolverMethod, target, args + continuation)
}
}
@Suppress("NOTHING_TO_INLINE")
private inline fun invoke(method: Method, instance: Any, args: Array): Any? {
try {
return method.invoke(instance, *args)
} catch (invocationException: java.lang.reflect.InvocationTargetException) {
val e = invocationException.cause
if (e is RuntimeException) {
throw e
}
if (e is Error) {
throw e
}
throw java.lang.reflect.UndeclaredThrowableException(e)
}
}
internal typealias ArgumentPlaceholder = (DataFetchingEnvironment) -> Any?