feat(type): allow type annotation options to be extracted

packages/type/src/reflection/type.ts

@@ -1548,7 +1548,9 @@ export interface EntityOptions {
  * const param1 = typeToObject(data[0]); //yes
  * ```
  */
-export type TypeAnnotation<T extends string, Options = never> = { __meta?: never & [T, Options] };
+export type TypeAnnotation<T extends string, Options = never> = { __meta?: [T, never | Options] };
+
+export type ExtractTypeAnnotationOptions<T extends TypeAnnotation<string, any>> = Exclude<NonNullable<T['__meta']>[1], never>;
 
 /**
  * Type to decorate an interface/object literal with entity information.
@@ -1994,34 +1996,25 @@ export function registerTypeDecorator(decorator: TypeDecorator) {
  * type MyAnnotation1<T> = TypeAnnotation<'myAnnotation', T>
  *
  * //under the hood it is:
- * type lowLevel1 = { __meta?: never & ['myAnnotation'] }
- * type lowLevel2<T> = { __meta?: never & ['myAnnotation', T] }
+ * type lowLevel1 = { __meta?: ['myAnnotation', never] }
+ * type lowLevel2<T> = { __meta?: ['myAnnotation', never | T] }
  * ```
  */
 export function getAnnotationMeta(type: TypeObjectLiteral): { id: string, params: Type[] } | undefined {
     const meta = getProperty(type, '__meta');
-    if (!meta || !meta.optional) return;
-    let tuple: TypeTuple | undefined = undefined;
 
-    if (meta.type.kind === ReflectionKind.intersection) {
-        if (meta.type.types.length === 1 && meta.type.types[0].kind === ReflectionKind.tuple) {
-            tuple = meta.type.types[0] as TypeTuple;
-        }
-        if (!tuple && meta.type.types.length === 2) {
-            tuple = meta.type.types.find(v => v.kind === ReflectionKind.tuple) as TypeTuple | undefined;
-            if (tuple && !meta.type.types.find(v => v.kind === ReflectionKind.never)) {
-                tuple = undefined;
-            }
-        }
-    } else if (meta.type.kind === ReflectionKind.tuple) {
-        tuple = meta.type;
-    }
+    if (!meta || !meta.optional) return;
+    if (meta.type.kind !== ReflectionKind.tuple) return;
 
-    if (!tuple) return;
+    const id = meta.type.types[0];
 
-    const id = tuple.types[0];
     if (!id || id.type.kind !== ReflectionKind.literal || 'string' !== typeof id.type.literal) return;
-    const params = tuple.types.slice(1).map(v => v.type);
+
+    const options = meta.type.types[1];
+    if (options.type.kind !== ReflectionKind.union) return;
+    if (options.type.types[0].kind !== ReflectionKind.never) return;
+
+    const params = options.type.types.slice(1);
 
     return { id: id.type.literal, params };
 }

packages/type/tests/annotations.spec.ts

@@ -0,0 +1,34 @@
+import { test, expect } from '@jest/globals';
+import { ExtractTypeAnnotationOptions, getAnnotationMeta, TypeAnnotation, TypeObjectLiteral } from '../src/reflection/type.js';
+import { typeOf } from '../src/reflection/reflection.js';
+import { expectEqualType } from './utils.js';
+
+test('extract type annotation options', () => {
+    type Skip = TypeAnnotation<'skip', { if: boolean }>;
+
+    type SkipOptions = ExtractTypeAnnotationOptions<Skip>;
+
+    const options: SkipOptions = {
+        if: true,
+    };
+});
+
+
+test('getAnnotationMeta', () => {
+    type LevelOptions = { do: boolean };
+
+    const levelOptionsType = typeOf<LevelOptions>();
+
+    type Level = TypeAnnotation<'level', LevelOptions>;
+
+    const levelType = typeOf<Level>() as TypeObjectLiteral;
+
+    const meta = getAnnotationMeta(levelType);
+
+    expect(meta).toBeDefined();
+
+    expect(meta!.id).toBe('level');
+
+    expectEqualType(meta!.params[0], levelOptionsType);
+
+});

packages/type/tests/integration4.spec.ts

@@ -9,7 +9,7 @@
  */
 
 import { expect, test } from '@jest/globals';
-import { assertType, AutoIncrement, Group, groupAnnotation, PrimaryKey, ReflectionKind } from '../src/reflection/type.js';
+import { assertType, AutoIncrement, ExtractTypeAnnotationOptions, Group, groupAnnotation, PrimaryKey, ReflectionKind, TypeAnnotation } from '../src/reflection/type.js';
 import { typeOf } from '../src/reflection/reflection.js';
 import { cast } from '../src/serializer-facade.js';