add param decorator

src/setter.ts

@@ -9,7 +9,7 @@ export type AllDecorators = MethodDecorator &
 export class MetadataSetter<M extends StringDict, AM extends StringDict> {
   private getMetadataInDecorator<
     K extends MergeKey<M, AM>,
-    GM extends Record<MergeKey<M, AM>, any> = GenericMap<M, AM>
+    GM extends Record<MergeKey<M, AM>, any> = GenericMap<M, AM>,
   >(metaKey: K, target: any, key?: any): GM[K] {
     if (key) {
       return Reflect.getMetadata(metaKey, target, key);
@@ -20,7 +20,7 @@ export class MetadataSetter<M extends StringDict, AM extends StringDict> {
 
   private setMetadataInDecorator<
     K extends MergeKey<M, AM>,
-    GM extends Record<MergeKey<M, AM>, any> = GenericMap<M, AM>
+    GM extends Record<MergeKey<M, AM>, any> = GenericMap<M, AM>,
   >(metaKey: K, value: GM[K], target: any, key?: any) {
     if (key) {
       return Reflect.defineMetadata(metaKey, value, target, key);
@@ -32,23 +32,13 @@ export class MetadataSetter<M extends StringDict, AM extends StringDict> {
   transform<
     K extends MergeKey<M, AM>,
     IK extends Key<AM>,
-    GM extends Record<MergeKey<M, AM>, any> = GenericMap<M, AM>
+    GM extends Record<MergeKey<M, AM>, any> = GenericMap<M, AM>,
   >(
     metadataKey: K,
     metadataValueFun: (oldValue: GM[K]) => GM[K],
     keysIndexMeta?: IK,
   ): AllDecorators {
-    return (target: any, key?: any, descriptorOrParamIndex?: number | any) => {
-      const descriptor =
-        typeof descriptorOrParamIndex === 'number'
-          ? undefined
-          : descriptorOrParamIndex;
-      /*
-      const paramIndex =
-        typeof descriptorOrParamIndex === 'number'
-          ? descriptorOrParamIndex
-          : undefined;
-       */
+    return (target, key?) => {
       const targetClass = getClass(target);
       const oldValue = this.getMetadataInDecorator<K, GM>(
         metadataKey,
@@ -122,4 +112,23 @@ export class MetadataSetter<M extends StringDict, AM extends StringDict> {
       keysIndexMeta,
     );
   }
+
+  param<K extends Key<AM>, IK extends Key<AM>>(
+    metadataKey: K,
+    metadataValue: AM[K],
+    keysIndexMeta?: IK,
+  ): ParameterDecorator {
+    return (obj, key, i) => {
+      const dec = this.transform<K, IK, ArrayValueMap<AM>>(
+        metadataKey,
+        (arr) => {
+          const newArr = arr || [];
+          newArr[i] = metadataValue;
+          return newArr;
+        },
+        keysIndexMeta,
+      );
+      dec(obj, key);
+    };
+  }
 }

src/utility/utility.ts

@@ -6,6 +6,7 @@ export function isClass(target: any) {
   return proto === Function;
 }
 
+// eslint-disable-next-line @typescript-eslint/ban-types
 export function getClass(target: any): Function {
   return isClass(target) ? target : getClass(target.constructor);
 }

tests/reflect.spec.ts

@@ -185,4 +185,31 @@ describe('Reflector', () => {
     expect(reflector.get('keys', B)).toEqual(['a', 'b']);
     expect(reflector.get('keys', b)).toEqual(['a', 'b']);
   });
+
+  it('should work with parameter decorators', () => {
+    class A {
+      constructor(
+        @Metadata.param('bar', 1) a: string,
+        @Metadata.param('bar', 2) b: string,
+      ) {}
+
+      method(
+        @Metadata.param('bar', 3) a: string,
+        @Metadata.param('bar', 4) b: string,
+      ) {}
+
+      static staticMethod(
+        @Metadata.param('bar', 5) a: string,
+        @Metadata.param('bar', 6) b: string,
+      ) {}
+    }
+
+    const a = new A('foo', 'bar');
+    expect(reflector.get('bar', A)).toStrictEqual([1, 2]);
+    expect(reflector.get('bar', a)).toStrictEqual([1, 2]);
+    expect(reflector.get('bar', A, 'method')).toStrictEqual([3, 4]);
+    expect(reflector.get('bar', a, 'method')).toStrictEqual([3, 4]);
+    expect(reflector.get('bar', A, 'staticMethod')).toStrictEqual([5, 6]);
+    expect(reflector.get('bar', a, 'staticMethod')).toStrictEqual([5, 6]);
+  });
 });