[generator] support input field deprecation (#1361)

With recent GraphQL spec changes, deprecation should be supported on fields, input fields (new), arguments (new) and enum values. This change adds the support for deprecating input fields.

Argument deprecation is not supported as Kotlin `@Deprecated` is not applicable to parameters. See https://youtrack.jetbrains.com/issue/KT-25643

Author: Dariusz Kuc

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

@@ -50,7 +50,7 @@ internal fun generateArgument(generator: SchemaGenerator, parameter: KParameter)
     val typeInfo = GraphQLKTypeMetadata(inputType = true, fieldName = parameter.getName(), fieldAnnotations = parameter.annotations)
     val graphQLType = generateGraphQLType(generator = generator, type = unwrappedType, typeInfo)
 
-    // Deprecation of arguments is currently unsupported: https://github.com/facebook/graphql/issues/197
+    // Deprecation of arguments is currently unsupported: https://youtrack.jetbrains.com/issue/KT-25643
     val builder = GraphQLArgument.newArgument()
         .name(parameter.getName())
         .description(parameter.getGraphQLDescription())

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2021 Expedia, Inc
+ * Copyright 2022 Expedia, Inc
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,7 +17,9 @@
 package com.expediagroup.graphql.generator.internal.types
 
 import com.expediagroup.graphql.generator.SchemaGenerator
+import com.expediagroup.graphql.generator.directives.deprecatedDirectiveWithReason
 import com.expediagroup.graphql.generator.internal.extensions.getPropertyAnnotations
+import com.expediagroup.graphql.generator.internal.extensions.getPropertyDeprecationReason
 import com.expediagroup.graphql.generator.internal.extensions.getPropertyDescription
 import com.expediagroup.graphql.generator.internal.extensions.getPropertyName
 import com.expediagroup.graphql.generator.internal.extensions.safeCast
@@ -29,18 +31,22 @@ import kotlin.reflect.KClass
 import kotlin.reflect.KProperty
 
 internal fun generateInputProperty(generator: SchemaGenerator, prop: KProperty<*>, parentClass: KClass<*>): GraphQLInputObjectField {
-    val builder = GraphQLInputObjectField.newInputObjectField()
-
-    // Verfiy that the unwrapped GraphQL type is a valid input type
+    // Verify that the unwrapped GraphQL type is a valid input type
     val inputTypeFromHooks = generator.config.hooks.willResolveInputMonad(prop.returnType)
     val unwrappedType = inputTypeFromHooks.unwrapOptionalInputType()
     val propertyName = prop.getPropertyName(parentClass)
     val typeInfo = GraphQLKTypeMetadata(inputType = true, fieldName = propertyName, fieldAnnotations = prop.getPropertyAnnotations(parentClass))
     val graphQLInputType = generateGraphQLType(generator = generator, type = unwrappedType, typeInfo).safeCast<GraphQLInputType>()
 
-    builder.name(propertyName)
-    builder.description(prop.getPropertyDescription(parentClass))
-    builder.type(graphQLInputType)
+    val builder = GraphQLInputObjectField.newInputObjectField()
+        .name(propertyName)
+        .description(prop.getPropertyDescription(parentClass))
+        .type(graphQLInputType)
+
+    prop.getPropertyDeprecationReason(parentClass)?.let {
+        builder.deprecate(it)
+        builder.withDirective(deprecatedDirectiveWithReason(it))
+    }
 
     generateDirectives(generator, prop, DirectiveLocation.INPUT_FIELD_DEFINITION, parentClass).forEach {
         builder.withDirective(it)

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019 Expedia, Inc
+ * Copyright 2022 Expedia, Inc
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,21 +21,21 @@ import com.expediagroup.graphql.generator.annotations.GraphQLName
 import com.expediagroup.graphql.generator.test.utils.SimpleDirective
 import org.junit.jupiter.api.Test
 import kotlin.test.assertEquals
+import kotlin.test.assertTrue
 
 internal class GenerateInputPropertyTest : TypeTestHelper() {
 
     private data class InputPropertyTestClass(
         @GraphQLDescription("Custom description")
         val description: String,
-
         @GraphQLName("newName")
         val changeMe: String,
-
         @SimpleDirective
         val directiveWithNoPrefix: String,
-
         @property:SimpleDirective
-        val directiveWithPrefix: String
+        val directiveWithPrefix: String,
+        @Deprecated("This field is deprecated")
+        val deprecatedDescription: String? = null
     )
 
     @Test
@@ -60,4 +60,11 @@ internal class GenerateInputPropertyTest : TypeTestHelper() {
         assertEquals(1, resultWithPrefix.directives.size)
         assertEquals("simpleDirective", resultWithPrefix.directives.first().name)
     }
+
+    @Test
+    fun `Input properties can be deprecated`() {
+        val deprecatedResult = generateInputProperty(generator, InputPropertyTestClass::deprecatedDescription, InputPropertyTestClass::class)
+        assertTrue(deprecatedResult.isDeprecated)
+        assertEquals("This field is deprecated", deprecatedResult.deprecationReason)
+    }
 }

website/docs/schema-generator/customizing-schemas/deprecating-schema.md

@@ -26,6 +26,6 @@ type Query {
 ```
 
 While you can deprecate any fields/functions/classes in your Kotlin code, GraphQL only supports deprecation directive on
-the fields (which correspond to Kotlin fields and functions) and enum values.
+the fields (which correspond to Kotlin properties and functions), input fields and enum values.
 
-Deprecation of input types is not yet supported [in the GraphQL spec](https://github.com/graphql/graphql-spec/pull/525).
+Deprecation of arguments is currently not supported [in Kotlin](https://youtrack.jetbrains.com/issue/KT-25643).