feat(core): require transform option if second type arg is provided

nestjs · Aug 24, 2023 · 7944f6e · 7944f6e
1 parent 22ffa76
commit 7944f6e
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Showing 2 changed files with 20 additions and 1 deletion.
diff --git a/packages/core/services/reflector.service.ts b/packages/core/services/reflector.service.ts
@@ -19,10 +19,18 @@ export interface CreateDecoratorOptions<TParam = any, TTransformed = TParam> {
   transform?: (value: TParam) => TTransformed;
 }
 
+export type CreateDecoratorWithTransformOptions<
+  TParam,
+  TTransformed = TParam,
+> = CreateDecoratorOptions<TParam, TTransformed> &
+  Required<Pick<CreateDecoratorOptions<TParam, TTransformed>, 'transform'>>;
+
 /**
  * @publicApi
  */
-export type ReflectableDecorator<TParam, TTransformedValue = TParam> = ((opts?: TParam) => CustomDecorator) & {
+export type ReflectableDecorator<TParam, TTransformedValue = TParam> = ((
+  opts?: TParam,
+) => CustomDecorator) & {
   KEY: string;
 };
 
@@ -40,6 +48,12 @@ export class Reflector {
    * @param options Decorator options.
    * @returns A decorator function.
    */
+  static createDecorator<TParam>(
+    options?: CreateDecoratorOptions<TParam>,
+  ): ReflectableDecorator<TParam, TParam>;
+  static createDecorator<TParam, TTransformed>(
+    options: CreateDecoratorWithTransformOptions<TParam, TTransformed>,
+  ): ReflectableDecorator<TParam, TTransformed>;
   static createDecorator<TParam, TTransformed = TParam>(
     options: CreateDecoratorOptions<TParam, TTransformed> = {},
   ): ReflectableDecorator<TParam, TTransformed> {

diff --git a/packages/core/test/services/reflector.service.spec.ts b/packages/core/test/services/reflector.service.spec.ts
@@ -56,6 +56,11 @@ describe('Reflector', () => {
       // @ts-expect-error 'value' is not assignable to type 'number'
       reflectedValue = [];
     });
+
+    it('should require transform option when second generic type is provided', () => {
+      // @ts-expect-error Property 'transform' is missing in type {} but required in type
+      const decorator = Reflector.createDecorator<string[], number>({});
+    });
   });
 
   describe('getAll', () => {