feat: pass DataFetcherEnvironment to arguments

example/src/main/kotlin/com/expedia/graphql/sample/model/ContextualResponse.kt

@@ -3,4 +3,4 @@ package com.expedia.graphql.sample.model
 import com.expedia.graphql.annotations.GraphQLDescription
 
 @GraphQLDescription("simple response that contains value read from context")
-data class ContextualResponse(val passedInValue: Int, val contextValue: String)
+data class ContextualResponse(val passedInValue: Int, val contextValue: String)

example/src/main/kotlin/com/expedia/graphql/sample/query/ContextualQuery.kt

@@ -11,7 +11,7 @@ import org.springframework.stereotype.Component
  * schema and will be automatically autowired at runtime using value from the environment.
  *
  * @see com.expedia.graphql.sample.context.MyGraphQLContextBuilder
- * @see com.expedia.graphql.FunctionDataFetcher
+ * @see com.expedia.graphql.execution.FunctionDataFetcher
  */
 @Component
 class ContextualQuery: Query {

example/src/main/kotlin/com/expedia/graphql/sample/query/EnvironmentQuery.kt

@@ -0,0 +1,24 @@
+package com.expedia.graphql.sample.query
+
+import graphql.schema.DataFetchingEnvironment
+import org.springframework.stereotype.Component
+
+@Component
+class EnvironmentQuery : Query {
+    fun nestedEnvironment(value: Int) = NestedNode(value)
+}
+
+data class NestedNode(
+    val value: Int,
+    val parentValue: Int? = null
+) {
+    fun nested(environment: DataFetchingEnvironment, value: Int): NestedNode {
+        val parentValue: Int? = if (environment.executionStepInfo.hasParent()) {
+            environment.executionStepInfo.parent.getArgument("value")
+        } else {
+            null
+        }
+
+        return NestedNode(value, parentValue)
+    }
+}

src/main/kotlin/com/expedia/graphql/execution/FunctionDataFetcher.kt

@@ -1,6 +1,7 @@
 package com.expedia.graphql.execution
 
 import com.expedia.graphql.generator.extensions.getName
+import com.expedia.graphql.generator.extensions.isDataFetchingEnvironment
 import com.expedia.graphql.generator.extensions.isGraphQLContext
 import com.expedia.graphql.generator.extensions.javaTypeClass
 import com.fasterxml.jackson.databind.ObjectMapper
@@ -51,14 +52,18 @@ class FunctionDataFetcher(
     }
 
     private fun mapParameterToValue(param: KParameter, environment: DataFetchingEnvironment): Any? =
-        if (param.isGraphQLContext()) {
-            environment.getContext()
-        } else {
-            val name = param.getName()
-            val klazz = param.javaTypeClass()
-            val value = objectMapper.convertValue(environment.arguments[name], klazz)
-            val predicateResult = executionPredicate?.evaluate(value = value, parameter = param, environment = environment)
-
-            predicateResult ?: value
+        when {
+            param.isGraphQLContext() -> environment.getContext()
+            param.isDataFetchingEnvironment() -> environment
+            else -> convertParameterValue(param, environment)
         }
+
+    private fun convertParameterValue(param: KParameter, environment: DataFetchingEnvironment): Any? {
+        val name = param.getName()
+        val klazz = param.javaTypeClass()
+        val value = objectMapper.convertValue(environment.arguments[name], klazz)
+        val predicateResult = executionPredicate?.evaluate(value = value, parameter = param, environment = environment)
+
+        return predicateResult ?: value
+    }
 }

src/main/kotlin/com/expedia/graphql/generator/extensions/kParameterExtensions.kt

@@ -2,13 +2,16 @@ package com.expedia.graphql.generator.extensions
 
 import com.expedia.graphql.annotations.GraphQLContext
 import com.expedia.graphql.exceptions.CouldNotGetNameOfKParameterException
+import graphql.schema.DataFetchingEnvironment
 import kotlin.reflect.KParameter
 import kotlin.reflect.full.findAnnotation
 
 internal fun KParameter.isInterface() = this.type.getKClass().isInterface()
 
 internal fun KParameter.isGraphQLContext() = this.findAnnotation<GraphQLContext>() != null
 
+internal fun KParameter.isDataFetchingEnvironment() = this.type.classifier == DataFetchingEnvironment::class
+
 @Throws(CouldNotGetNameOfKParameterException::class)
 internal fun KParameter.getName(): String =
     this.name ?: throw CouldNotGetNameOfKParameterException(this)

src/main/kotlin/com/expedia/graphql/generator/types/FunctionTypeBuilder.kt

@@ -7,6 +7,7 @@ import com.expedia.graphql.generator.extensions.getDeprecationReason
 import com.expedia.graphql.generator.extensions.getGraphQLDescription
 import com.expedia.graphql.generator.extensions.getName
 import com.expedia.graphql.generator.extensions.getTypeOfFirstArgument
+import com.expedia.graphql.generator.extensions.isDataFetchingEnvironment
 import com.expedia.graphql.generator.extensions.isGraphQLContext
 import com.expedia.graphql.generator.extensions.isInterface
 import com.expedia.graphql.generator.extensions.safeCast
@@ -37,6 +38,7 @@ internal class FunctionTypeBuilder(generator: SchemaGenerator) : TypeBuilder(gen
 
         fn.valueParameters
             .filterNot { it.isGraphQLContext() }
+            .filterNot { it.isDataFetchingEnvironment() }
             .forEach {
                 // deprecation of arguments is currently unsupported: https://github.com/facebook/graphql/issues/197
                 builder.argument(argument(it))

src/test/kotlin/com/expedia/graphql/execution/FunctionDataFetcherTest.kt

@@ -20,6 +20,8 @@ internal class FunctionDataFetcherTest {
         fun printList(items: List<String>) = items.joinToString(separator = ":")
 
         fun context(@GraphQLContext string: String) = string
+
+        fun dataFetchingEnvironment(environment: DataFetchingEnvironment) = environment.field.name
     }
 
     @Test
@@ -93,4 +95,14 @@ internal class FunctionDataFetcherTest {
             dataFetcher.get(mockEnvironmet)
         }
     }
+
+    @Test
+    fun `dataFetchingEnvironement is passed as an argument`() {
+        val dataFetcher = FunctionDataFetcher(target = MyClass(), fn = MyClass::dataFetchingEnvironment)
+        val mockEnvironmet: DataFetchingEnvironment = mockk()
+        every { mockEnvironmet.field } returns mockk {
+            every { name } returns "fooBarBaz"
+        }
+        assertEquals(expected = "fooBarBaz", actual = dataFetcher.get(mockEnvironmet))
+    }
 }

src/test/kotlin/com/expedia/graphql/generator/extensions/KParameterExtensionsKtTest.kt

@@ -2,6 +2,7 @@ package com.expedia.graphql.generator.extensions
 
 import com.expedia.graphql.annotations.GraphQLDescription
 import com.expedia.graphql.exceptions.CouldNotGetNameOfKParameterException
+import graphql.schema.DataFetchingEnvironment
 import io.mockk.every
 import io.mockk.mockk
 import org.junit.jupiter.api.Test
@@ -29,6 +30,8 @@ internal class KParameterExtensionsKtTest {
         internal fun noDescription(myClass: MyClass) = myClass
 
         internal fun paramDescription(@GraphQLDescription("param description") myClass: MyClass) = myClass
+
+        internal fun dataFetchingEnvironment(environment: DataFetchingEnvironment) = environment.field.name
     }
 
     @Test
@@ -69,4 +72,16 @@ internal class KParameterExtensionsKtTest {
         val param = Container::interfaceInput.findParameterByName("myInterface")
         assertTrue(param?.isInterface().isTrue())
     }
+
+    @Test
+    fun `valid DataFetchingEnvironment passes`() {
+        val param = Container::dataFetchingEnvironment.findParameterByName("environment")
+        assertTrue(param?.isDataFetchingEnvironment().isTrue())
+    }
+
+    @Test
+    fun `invalid DataFetchingEnvironment fails`() {
+        val param = Container::interfaceInput.findParameterByName("myInterface")
+        assertFalse(param?.isDataFetchingEnvironment().isTrue())
+    }
 }

src/test/kotlin/com/expedia/graphql/generator/types/FunctionTypeBuilderTest.kt

@@ -6,6 +6,7 @@ import com.expedia.graphql.annotations.GraphQLDirective
 import com.expedia.graphql.execution.FunctionDataFetcher
 import graphql.Scalars
 import graphql.introspection.Introspection
+import graphql.schema.DataFetchingEnvironment
 import graphql.schema.GraphQLNonNull
 import org.junit.jupiter.api.Test
 import java.util.UUID
@@ -52,6 +53,8 @@ internal class FunctionTypeBuilderTest : TypeTestHelper() {
         fun context(@GraphQLContext context: String, string: String) = "$context and $string"
 
         fun completableFuture(num: Int): CompletableFuture<Int> = CompletableFuture.completedFuture(num)
+
+        fun dataFetchingEnvironment(environment: DataFetchingEnvironment): String = environment.field.name
     }
 
     @Test
@@ -160,4 +163,13 @@ internal class FunctionTypeBuilderTest : TypeTestHelper() {
         assertEquals(expected = 1, actual = result.arguments.size)
         assertEquals("Int", (result.type as? GraphQLNonNull)?.wrappedType?.name)
     }
+
+    @Test
+    fun `DataFetchingEnvironment argument type is ignored`() {
+        val kFunction = Happy::dataFetchingEnvironment
+        val result = builder.function(fn = kFunction)
+
+        assertEquals(expected = 0, actual = result.arguments.size)
+        assertEquals("String", (result.type as? GraphQLNonNull)?.wrappedType?.name)
+    }
 }