fix(schema): fix Default decorator signature

Closes: #2968

Author: Romakita

packages/specs/schema/src/components/default/schemaMapper.ts

@@ -1,4 +1,4 @@
-import {getValue, isObject} from "@tsed/core";
+import {getValue, isFunction, isObject} from "@tsed/core";
 
 import {mapAliasedProperties} from "../../domain/JsonAliasMap.js";
 import {JsonSchema} from "../../domain/JsonSchema.js";
@@ -127,6 +127,10 @@ function serializeSchema(schema: JsonSchema, options: JsonSchemaOptions) {
     };
   }
 
+  if (isFunction(obj.default)) {
+    obj.default = obj.default();
+  }
+
   obj = execMapper("required", [obj, schema], options);
   obj = execMapper("nullable", [obj, schema], options);
   obj = alterOneOf(obj, schema, options);

packages/specs/schema/src/decorators/common/default.spec.ts

@@ -22,4 +22,24 @@ describe("@Default", () => {
       type: "object"
     });
   });
+  it("should declare prop (Date.now)", () => {
+    // WHEN
+    class Model {
+      @Default(Date.now)
+      num: Date = new Date();
+
+      constructor() {}
+    }
+
+    // THEN
+    expect(getJsonSchema(Model)).toEqual({
+      properties: {
+        num: {
+          default: expect.any(Number),
+          type: "string"
+        }
+      },
+      type: "object"
+    });
+  });
 });

packages/specs/schema/src/decorators/common/default.ts

@@ -42,7 +42,7 @@ import {JsonEntityFn} from "./jsonEntityFn.js";
  * @schema
  * @input
  */
-export function Default(defaultValue: JSONSchema6Type | undefined) {
+export function Default(defaultValue: JSONSchema6Type | undefined | (() => JSONSchema6Type)) {
   return JsonEntityFn((store) => {
     store.itemSchema.default(defaultValue);
   });

packages/specs/schema/src/domain/JsonSchema.ts

@@ -259,7 +259,7 @@ export class JsonSchema extends Map<string, any> implements NestedGenerics {
    * It is RECOMMENDED that a default value be valid against the associated schema.
    * @see https://tools.ietf.org/html/draft-wright-json-schema-validation-01#section-7.3
    */
-  default(value: JSONSchema6Type | undefined) {
+  default(value: JSONSchema6Type | undefined | (() => JSONSchema6Type)) {
     super.set("default", value);
 
     return this;