Fix #413: allow nested defaults on objects.

.eslintignore

@@ -1 +1,2 @@
 examples
+sandbox.js

README.md

@@ -437,10 +437,13 @@ Strict mode sets the `options.convert` options to `false` which prevent type cas
 var schema = Joi.any().strict();
 ```
 
-#### `any.default(value, [description])`
+#### `any.default([value, [description]])`
 
 Sets a default value if the original value is undefined where:
-- `value` - the value. `value` supports [references](#refkey-options). `value` may also be a function which returns the default value. If `value` is specified as a function that accepts a single parameter, that parameter will be a context object that can be used to derive the resulting value. **This clones the object however, which incurs some overhead so if you don't need access to the context define your method so that it does not accept any parameters**.
+- `value` - the value.
+  - `value` supports [references](#refkey-options).
+  - `value` may also be a function which returns the default value. If `value` is specified as a function that accepts a single parameter, that parameter will be a context object that can be used to derive the resulting value. **This clones the object however, which incurs some overhead so if you don't need access to the context define your method so that it does not accept any parameters**.
+  - without any `value`, `default` has no effect, except for `object` that will then create nested defaults (applying inner defaults of that object).
 
 Note that if `value` is an object, any changes to the object after `default()` is called will change the reference
 and any future assignment.

lib/any.js

@@ -500,7 +500,13 @@ internals.Any.prototype._validate = function (value, state, options, reference)
     var presence = this._flags.presence || options.presence;
     if (presence === 'optional') {
         if (value === undefined) {
-            return finish();
+            var isDeepDefault = this._flags.hasOwnProperty('default') && this._flags.default === undefined;
+            if (isDeepDefault && this._type === 'object') {
+                value = {};
+            }
+            else {
+                return finish();
+            }
         }
     }
     else if (presence === 'required' &&

test/any.js

@@ -506,6 +506,34 @@ describe('any', function () {
                 done();
             });
         });
+
+        it('creates deep defaults', function (done) {
+
+            var schema = Joi.object({
+                a: Joi.number().default(42),
+                b: Joi.object({
+                    c: Joi.boolean().default(true),
+                    d: Joi.string()
+                }).default()
+            }).default();
+
+            Helper.validate(schema, [
+                [undefined, true, null, { a: 42, b: { c: true }}],
+                [{ a: 24 }, true, null, { a: 24, b: { c: true }}]
+            ], done);
+        });
+
+        it('should not affect objects other than object when called without an argument', function (done) {
+
+            var schema = Joi.object({
+                a: Joi.number().default()
+            }).default();
+
+            Helper.validate(schema, [
+                [undefined, true, null, {}],
+                [{ a: 24 }, true, null, { a: 24 }]
+            ], done);
+        });
     });
 
     describe('#optional', function () {