From 4d8b5aea80eda980b870cd19970fdb7d78eb15f0 Mon Sep 17 00:00:00 2001
From: riley-pikus <riley.pikus@mastery.net>
Date: Wed, 20 Aug 2025 16:07:10 -0500
Subject: [PATCH] feat(@nestjs/graphql): Allow InputType Deprecation (code
 first)

---
 .../input-type-definition.factory.ts          |  1 +
 .../input-type-definition.factory.spec.ts     | 56 +++++++++++++++++++
 2 files changed, 57 insertions(+)
 create mode 100644 packages/graphql/tests/schema-builder/factories/input-type-definition.factory.spec.ts

diff --git a/packages/graphql/lib/schema-builder/factories/input-type-definition.factory.ts b/packages/graphql/lib/schema-builder/factories/input-type-definition.factory.ts
index 788a3ba76..212d3b784 100644
--- a/packages/graphql/lib/schema-builder/factories/input-type-definition.factory.ts
+++ b/packages/graphql/lib/schema-builder/factories/input-type-definition.factory.ts
@@ -80,6 +80,7 @@ export class InputTypeDefinitionFactory {
           description: property.description,
           type,
           defaultValue: property.options.defaultValue,
+          deprecationReason: property.deprecationReason,
           /**
            * AST node has to be manually created in order to define directives
            * (more on this topic here: https://github.com/graphql/graphql-js/issues/1343)
diff --git a/packages/graphql/tests/schema-builder/factories/input-type-definition.factory.spec.ts b/packages/graphql/tests/schema-builder/factories/input-type-definition.factory.spec.ts
new file mode 100644
index 000000000..a0035d4e4
--- /dev/null
+++ b/packages/graphql/tests/schema-builder/factories/input-type-definition.factory.spec.ts
@@ -0,0 +1,56 @@
+import { Test } from '@nestjs/testing';
+import {
+  Field,
+  InputType,
+  GraphQLSchemaBuilderModule,
+  TypeMetadataStorage,
+} from '../../../lib';
+import { TypeDefinitionsGenerator } from '../../../lib/schema-builder/type-definitions.generator';
+import { TypeDefinitionsStorage } from '../../../lib/schema-builder/storages/type-definitions.storage';
+import { LazyMetadataStorage } from '../../../lib/schema-builder/storages/lazy-metadata.storage';
+
+@InputType('DeprecationInput')
+class DeprecationInput {
+  @Field(() => String, { description: 'regular' })
+  regular!: string;
+
+  @Field(() => String, {
+    description: 'deprecated',
+    deprecationReason: 'use something else',
+  })
+  oldField!: string;
+}
+
+describe('InputTypeDefinitionFactory (deprecation)', () => {
+  let generator: TypeDefinitionsGenerator;
+  let storage: TypeDefinitionsStorage;
+
+  beforeAll(async () => {
+    // Register metadata for the input type
+    LazyMetadataStorage.load([DeprecationInput]);
+    TypeMetadataStorage.compile();
+
+    const moduleRef = await Test.createTestingModule({
+      imports: [GraphQLSchemaBuilderModule],
+    }).compile();
+
+    generator = moduleRef.get(TypeDefinitionsGenerator);
+    storage = moduleRef.get(TypeDefinitionsStorage);
+  });
+
+  afterAll(() => {
+    TypeMetadataStorage.clear();
+  });
+
+  it('should mark input fields as deprecated if value is set', () => {
+    // Generate type definitions (inputs included)
+    generator.generate({} as any);
+
+    const inputType: any = storage.getInputTypeAndExtract(DeprecationInput);
+    expect(inputType).toBeDefined();
+
+    const fields = inputType.getFields();
+    expect(fields.regular.deprecationReason).toBeUndefined();
+    expect(fields.oldField.deprecationReason).toBe('use something else');
+  });
+});