Allow data and errors to be returned with DataFetcherResult (ExpediaGroup#342)

* Allow data and errors to be returned with DataFetcherResult

Fixes ExpediaGroup#244
Rebase of ExpediaGroup#245

Kotlin functions can now return a DataFetcherResult instead of just their return type which allows you to modify the errors field with any extra data you need

* Move output type monad code into the generator

* Move unwrapping logic back to function builder

* Add unit test for publisher implementation

Author: smyrick

examples/spring/src/main/kotlin/com/expediagroup/graphql/sample/query/DataAndErrors.kt

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2019 Expedia, Inc
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.expediagroup.graphql.sample.query
+
+import graphql.ExceptionWhileDataFetching
+import graphql.execution.DataFetcherResult
+import graphql.execution.ExecutionPath
+import graphql.language.SourceLocation
+import org.springframework.stereotype.Component
+import java.util.concurrent.CompletableFuture
+
+@Component
+class DataAndErrors : Query {
+
+    fun returnDataAndErrors(): DataFetcherResult<String> {
+        val error = ExceptionWhileDataFetching(ExecutionPath.rootPath(), RuntimeException(), SourceLocation(1, 1))
+        return DataFetcherResult.newResult<String>()
+            .data("Hello from data fetcher")
+            .error(error)
+            .build()
+    }
+
+    fun completableFutureDataAndErrors(): CompletableFuture<DataFetcherResult<String>> {
+        val error = ExceptionWhileDataFetching(ExecutionPath.rootPath(), RuntimeException(), SourceLocation(1, 1))
+        val dataFetcherResult = DataFetcherResult.newResult<String>()
+            .data("Hello from data fetcher")
+            .error(error)
+            .build()
+
+        return CompletableFuture.completedFuture(dataFetcherResult)
+    }
+}

graphql-kotlin-schema-generator/src/main/kotlin/com/expediagroup/graphql/generator/extensions/kClassExtensions.kt

@@ -62,11 +62,7 @@ internal fun KClass<*>.isUnion(): Boolean =
 
 internal fun KClass<*>.isEnum(): Boolean = this.isSubclassOf(Enum::class)
 
-internal fun KClass<*>.isList(): Boolean = this.isSubclassOf(List::class)
-
-internal fun KClass<*>.isArray(): Boolean = this.java.isArray
-
-internal fun KClass<*>.isListType(): Boolean = this.isList() || this.isArray()
+internal fun KClass<*>.isListType(): Boolean = this.isSubclassOf(List::class) || this.java.isArray
 
 @Throws(CouldNotGetNameOfKClassException::class)
 internal fun KClass<*>.getSimpleName(isInputClass: Boolean = false): String {

graphql-kotlin-schema-generator/src/main/kotlin/com/expediagroup/graphql/generator/extensions/kTypeExtensions.kt

@@ -17,8 +17,10 @@
 package com.expediagroup.graphql.generator.extensions
 
 import com.expediagroup.graphql.exceptions.InvalidListTypeException
+import kotlin.reflect.KClass
 import kotlin.reflect.KType
 import kotlin.reflect.full.createType
+import kotlin.reflect.full.isSubclassOf
 import kotlin.reflect.jvm.jvmErasure
 
 private val primitiveArrayTypes = mapOf(
@@ -33,6 +35,8 @@ private val primitiveArrayTypes = mapOf(
 
 internal fun KType.getKClass() = this.jvmErasure
 
+internal fun KType.isSubclassOf(kClass: KClass<*>) = this.getKClass().isSubclassOf(kClass)
+
 @Throws(InvalidListTypeException::class)
 internal fun KType.getTypeOfFirstArgument(): KType =
     this.arguments.firstOrNull()?.type ?: throw InvalidListTypeException(this)

graphql-kotlin-schema-generator/src/main/kotlin/com/expediagroup/graphql/generator/types/FunctionBuilder.kt

@@ -22,18 +22,13 @@ import com.expediagroup.graphql.generator.TypeBuilder
 import com.expediagroup.graphql.generator.extensions.getDeprecationReason
 import com.expediagroup.graphql.generator.extensions.getFunctionName
 import com.expediagroup.graphql.generator.extensions.getGraphQLDescription
-import com.expediagroup.graphql.generator.extensions.getKClass
-import com.expediagroup.graphql.generator.extensions.getTypeOfFirstArgument
 import com.expediagroup.graphql.generator.extensions.getValidArguments
 import com.expediagroup.graphql.generator.extensions.safeCast
+import com.expediagroup.graphql.generator.types.utils.getWrappedReturnType
 import graphql.schema.FieldCoordinates
 import graphql.schema.GraphQLFieldDefinition
 import graphql.schema.GraphQLOutputType
-import org.reactivestreams.Publisher
-import java.util.concurrent.CompletableFuture
 import kotlin.reflect.KFunction
-import kotlin.reflect.KType
-import kotlin.reflect.full.isSubclassOf
 
 internal class FunctionBuilder(generator: SchemaGenerator) : TypeBuilder(generator) {
 
@@ -58,22 +53,15 @@ internal class FunctionBuilder(generator: SchemaGenerator) : TypeBuilder(generat
 
         val typeFromHooks = config.hooks.willResolveMonad(fn.returnType)
         val returnType = getWrappedReturnType(typeFromHooks)
-        builder.type(graphQLTypeOf(returnType).safeCast<GraphQLOutputType>())
-        val graphQLType = builder.build()
-
+        val graphQLOutputType = graphQLTypeOf(returnType).safeCast<GraphQLOutputType>()
+        val graphQLType = builder.type(graphQLOutputType).build()
         val coordinates = FieldCoordinates.coordinates(parentName, functionName)
+
         if (!abstract) {
             val dataFetcherFactory = config.dataFetcherFactoryProvider.functionDataFetcherFactory(target = target, kFunction = fn)
             generator.codeRegistry.dataFetcher(coordinates, dataFetcherFactory)
         }
 
         return config.hooks.onRewireGraphQLType(graphQLType, coordinates, codeRegistry).safeCast()
     }
-
-    private fun getWrappedReturnType(returnType: KType): KType =
-        when {
-            returnType.getKClass().isSubclassOf(Publisher::class) -> returnType.getTypeOfFirstArgument()
-            returnType.classifier == CompletableFuture::class -> returnType.getTypeOfFirstArgument()
-            else -> returnType
-        }
 }

graphql-kotlin-schema-generator/src/main/kotlin/com/expediagroup/graphql/generator/types/utils/functionReturnTypes.kt

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2019 Expedia, Inc
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.expediagroup.graphql.generator.types.utils
+
+import com.expediagroup.graphql.generator.extensions.getTypeOfFirstArgument
+import com.expediagroup.graphql.generator.extensions.isSubclassOf
+import graphql.execution.DataFetcherResult
+import org.reactivestreams.Publisher
+import java.util.concurrent.CompletableFuture
+import kotlin.reflect.KType
+
+/**
+ * These are the classes that can be returned from data fetchers (ie functions)
+ * but we only want to expose the wrapped type in the schema.
+ *
+ * [Publisher] is used for subscriptions
+ * [CompletableFuture] is used for asynchronous results
+ * [DataFetcherResult] is used for returning data and errors in the same response
+ *
+ * We can return the following combination of types:
+ *      Valid type T
+ *      Publisher<T>
+ *      DataFetcherResult<T>
+ *      CompletableFuture<T>
+ *      CompletableFuture<DataFetcherResult<T>>
+ */
+internal fun getWrappedReturnType(returnType: KType): KType {
+    return when {
+        returnType.isSubclassOf(Publisher::class) -> returnType.getTypeOfFirstArgument()
+        returnType.isSubclassOf(DataFetcherResult::class) -> returnType.getTypeOfFirstArgument()
+        returnType.isSubclassOf(CompletableFuture::class) -> {
+            val wrappedType = returnType.getTypeOfFirstArgument()
+
+            if (wrappedType.isSubclassOf(DataFetcherResult::class)) {
+                return wrappedType.getTypeOfFirstArgument()
+            }
+
+            wrappedType
+        }
+        else -> returnType
+    }
+}

graphql-kotlin-schema-generator/src/test/kotlin/com/expediagroup/graphql/generator/SchemaGeneratorTest.kt

@@ -27,8 +27,12 @@ import com.expediagroup.graphql.exceptions.InvalidIdTypeException
 import com.expediagroup.graphql.extensions.deepName
 import com.expediagroup.graphql.testSchemaConfig
 import com.expediagroup.graphql.toSchema
+import graphql.ExceptionWhileDataFetching
 import graphql.GraphQL
 import graphql.Scalars
+import graphql.execution.DataFetcherResult
+import graphql.execution.ExecutionPath
+import graphql.language.SourceLocation
 import graphql.schema.GraphQLFieldDefinition
 import graphql.schema.GraphQLNonNull
 import graphql.schema.GraphQLObjectType
@@ -353,6 +357,23 @@ class SchemaGeneratorTest {
         assertEquals(Scalars.GraphQLID, serialField?.wrappedType)
     }
 
+    @Test
+    fun `SchemaGenerator supports DataFetcherResult as a return type`() {
+        val schema = toSchema(queries = listOf(TopLevelObject(QueryWithDataFetcherResult())), config = testSchemaConfig)
+
+        val graphQL = GraphQL.newGraphQL(schema).build()
+        val result = graphQL.execute("{ dataAndErrors }")
+        val data = result.getData<Map<String, String>>()
+        val errors = result.errors
+
+        assertNotNull(data)
+        val res: String? = data["dataAndErrors"]
+        assertEquals(actual = res, expected = "Hello")
+
+        assertNotNull(errors)
+        assertEquals(expected = 1, actual = errors.size)
+    }
+
     class QueryObject {
         @GraphQLDescription("A GraphQL query method")
         fun query(@GraphQLDescription("A GraphQL value") value: Int): Geography = Geography(value, GeoType.CITY, listOf())
@@ -550,4 +571,11 @@ class SchemaGeneratorTest {
         @GraphQLID val serial: UUID,
         val type: String
     )
+
+    class QueryWithDataFetcherResult {
+        fun dataAndErrors(): DataFetcherResult<String> {
+            val error = ExceptionWhileDataFetching(ExecutionPath.rootPath(), RuntimeException(), SourceLocation(1, 1))
+            return DataFetcherResult.newResult<String>().data("Hello").error(error).build()
+        }
+    }
 }

graphql-kotlin-schema-generator/src/test/kotlin/com/expediagroup/graphql/generator/extensions/KClassExtensionsTest.kt

@@ -187,22 +187,6 @@ open class KClassExtensionsTest {
         assertFalse(MyTestClass::class.isEnum())
     }
 
-    @Test
-    fun `test list extension`() {
-        assertTrue(listOf(1)::class.isList())
-        assertTrue(arrayListOf(1)::class.isList())
-        assertFalse(arrayOf(1)::class.isList())
-        assertFalse(MyTestClass::class.isList())
-    }
-
-    @Test
-    fun `test array extension`() {
-        assertTrue(arrayOf(1)::class.isArray())
-        assertTrue(intArrayOf(1)::class.isArray())
-        assertFalse(listOf(1)::class.isArray())
-        assertFalse(MyTestClass::class.isArray())
-    }
-
     @Test
     fun `test listType extension`() {
         assertTrue(arrayOf(1)::class.isListType())

graphql-kotlin-schema-generator/src/test/kotlin/com/expediagroup/graphql/generator/extensions/KTypeExtensionsKtTest.kt

@@ -27,6 +27,8 @@ import kotlin.reflect.full.findParameterByName
 import kotlin.reflect.full.starProjectedType
 import kotlin.test.assertEquals
 import kotlin.test.assertFailsWith
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
 
 internal class KTypeExtensionsKtTest {
 
@@ -40,6 +42,10 @@ internal class KTypeExtensionsKtTest {
         fun stringFun(string: String) = "hello $string"
     }
 
+    internal interface SimpleInterface
+
+    internal class SimpleClass(val id: String) : SimpleInterface
+
     @Test
     fun getTypeOfFirstArgument() {
         assertEquals(String::class.starProjectedType, MyClass::listFun.findParameterByName("list")?.type?.getTypeOfFirstArgument())
@@ -72,6 +78,14 @@ internal class KTypeExtensionsKtTest {
         assertEquals(MyClass::class, MyClass::class.starProjectedType.getKClass())
     }
 
+    @Test
+    fun isSubclassOf() {
+        assertTrue(MyClass::class.starProjectedType.isSubclassOf(MyClass::class))
+        assertTrue(SimpleClass::class.starProjectedType.isSubclassOf(SimpleInterface::class))
+        assertFalse(SimpleInterface::class.starProjectedType.isSubclassOf(SimpleClass::class))
+        assertFalse(MyClass::class.starProjectedType.isSubclassOf(SimpleInterface::class))
+    }
+
     @Test
     fun getArrayType() {
         assertEquals(Int::class.starProjectedType, IntArray::class.starProjectedType.getWrappedType())

graphql-kotlin-schema-generator/src/test/kotlin/com/expediagroup/graphql/generator/types/FunctionBuilderTest.kt

@@ -21,18 +21,26 @@ import com.expediagroup.graphql.annotations.GraphQLDescription
 import com.expediagroup.graphql.annotations.GraphQLDirective
 import com.expediagroup.graphql.annotations.GraphQLIgnore
 import com.expediagroup.graphql.annotations.GraphQLName
+import com.expediagroup.graphql.exceptions.TypeNotSupportedException
 import com.expediagroup.graphql.execution.FunctionDataFetcher
+import graphql.ExceptionWhileDataFetching
 import graphql.Scalars
+import graphql.execution.DataFetcherResult
+import graphql.execution.ExecutionPath
 import graphql.introspection.Introspection
+import graphql.language.SourceLocation
 import graphql.schema.DataFetchingEnvironment
 import graphql.schema.FieldCoordinates
+import graphql.schema.GraphQLList
 import graphql.schema.GraphQLNonNull
+import graphql.schema.GraphQLTypeUtil
 import io.reactivex.Flowable
 import org.junit.jupiter.api.Test
 import org.reactivestreams.Publisher
 import java.util.UUID
 import java.util.concurrent.CompletableFuture
 import kotlin.test.assertEquals
+import kotlin.test.assertFailsWith
 import kotlin.test.assertTrue
 
 @Suppress("Detekt.UnusedPrivateClass")
@@ -78,6 +86,25 @@ internal class FunctionBuilderTest : TypeTestHelper() {
         fun completableFuture(num: Int): CompletableFuture<Int> = CompletableFuture.completedFuture(num)
 
         fun dataFetchingEnvironment(environment: DataFetchingEnvironment): String = environment.field.name
+
+        fun dataFetcherResult(): DataFetcherResult<String> {
+            val error = ExceptionWhileDataFetching(ExecutionPath.rootPath(), RuntimeException(), SourceLocation(1, 1))
+            return DataFetcherResult.newResult<String>().data("Hello").error(error).build()
+        }
+
+        fun listDataFetcherResult(): DataFetcherResult<List<String>> = DataFetcherResult.newResult<List<String>>().data(listOf("Hello")).build()
+
+        fun nullalbeListDataFetcherResult(): DataFetcherResult<List<String?>?> = DataFetcherResult.newResult<List<String?>?>().data(listOf("Hello")).build()
+
+        fun dataFetcherCompletableFutureResult(): DataFetcherResult<CompletableFuture<String>> {
+            val completedFuture = CompletableFuture.completedFuture("Hello")
+            return DataFetcherResult.newResult<CompletableFuture<String>>().data(completedFuture).build()
+        }
+
+        fun completableFutureDataFetcherResult(): CompletableFuture<DataFetcherResult<String>> {
+            val dataFetcherResult = DataFetcherResult.newResult<String>().data("Hello").build()
+            return CompletableFuture.completedFuture(dataFetcherResult)
+        }
     }
 
     @Test
@@ -205,4 +232,54 @@ internal class FunctionBuilderTest : TypeTestHelper() {
         assertEquals(expected = 0, actual = result.arguments.size)
         assertEquals("String", (result.type as? GraphQLNonNull)?.wrappedType?.name)
     }
+
+    @Test
+    fun `DataFetcherResult return type is valid and unwrapped in the schema`() {
+        val kFunction = Happy::dataFetcherResult
+        val result = builder.function(fn = kFunction, parentName = "Query", target = null, abstract = false)
+
+        assertEquals("String", (result.type as? GraphQLNonNull)?.wrappedType?.name)
+    }
+
+    @Test
+    fun `DataFetcherResult of a List is valid and unwrapped in the schema`() {
+        val kFunction = Happy::listDataFetcherResult
+        val result = builder.function(fn = kFunction, parentName = "Query", target = null, abstract = false)
+
+        assertTrue(result.type is GraphQLNonNull)
+        val listType = GraphQLTypeUtil.unwrapNonNull(result.type)
+        assertTrue(listType is GraphQLList)
+        val stringType = GraphQLTypeUtil.unwrapNonNull(GraphQLTypeUtil.unwrapOne(listType))
+        assertEquals("String", stringType.name)
+    }
+
+    @Test
+    fun `DataFetcherResult of a nullable List is valid and unwrapped in the schema`() {
+        val kFunction = Happy::nullalbeListDataFetcherResult
+        val result = builder.function(fn = kFunction, parentName = "Query", target = null, abstract = false)
+
+        val listType = result.type
+        assertTrue(listType is GraphQLList)
+        val stringType = listType.wrappedType
+        assertEquals("String", stringType.name)
+    }
+
+    @Test
+    fun `DataFetcherResult of a CompletableFuture is invalid`() {
+        val kFunction = Happy::dataFetcherCompletableFutureResult
+
+        assertFailsWith(TypeNotSupportedException::class) {
+            builder.function(fn = kFunction, parentName = "Query", target = null, abstract = false)
+        }
+    }
+
+    @Test
+    fun `CompletableFuture of a DataFetcherResult is valid and unwrapped in the schema`() {
+        val kFunction = Happy::completableFutureDataFetcherResult
+        val result = builder.function(fn = kFunction, parentName = "Query", target = null, abstract = false)
+
+        assertTrue(result.type is GraphQLNonNull)
+        val stringType = GraphQLTypeUtil.unwrapNonNull(result.type)
+        assertEquals("String", stringType.name)
+    }
 }