Add a new property option `defaultFn`

The property allows developers to specify that the default value
should be retrieved via a named function.

Only two built-in functions are supported at the moment:

  "guid", "uuid" - generate a new GUID/UUID
  "now" - use the current date and time

Support for custom (user-provided) functions is not implemented yet.

lib/model.js

@@ -16,6 +16,7 @@ var validations = require('./validations');
 var _extend = util._extend;
 var utils = require('./utils');
 var fieldsToArray = utils.fieldsToArray;
+var uuid = require('node-uuid');
 
 // Set up an object for quick lookup
 var BASE_TYPES = {
@@ -228,10 +229,34 @@ ModelBaseClass.prototype._initProperties = function (data, options) {
         }
         // FIXME: We should coerce the value
         // will implement it after we refactor the PropertyDefinition
-        self.__data[p] = def;
+        self.__data[p] = propVal = def;
       }
     }
 
+    // Set default value using a named function
+    if (propVal === undefined) {
+      var defn = properties[p].defaultFn;
+      switch (defn) {
+        case undefined:
+          break;
+        case 'guid':
+        case 'uuid':
+          // Generate a v1 (time-based) id
+          propVal = uuid.v1();
+          break;
+        case 'now':
+          propVal = new Date();
+          break;
+        default:
+          // TODO Support user-provided functions via a registry of functions
+          console.warn('Unknown default value provider ' + defn);
+      }
+      // FIXME: We should coerce the value
+      // will implement it after we refactor the PropertyDefinition
+      if (propVal !== undefined)
+        self.__data[p] = propVal;
+    }
+
     // Handle complex types (JSON/Object)
     if (!BASE_TYPES[type.name]) {
 

package.json

@@ -33,6 +33,7 @@
     "inflection": "^1.6.0",
     "lodash": "~3.0.1",
     "loopback-connector": "1.x",
+    "node-uuid": "^1.4.2",
     "qs": "^2.3.3",
     "traverse": "^0.6.6"
   },

test/manipulation.test.js

@@ -4,6 +4,8 @@ var should = require('./init.js');
 var db, Person;
 var ValidationError = require('..').ValidationError;
 
+var UUID_REGEXP = /^[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i;
+
 describe('manipulation', function () {
 
   before(function (done) {
@@ -471,6 +473,42 @@ describe('manipulation', function () {
 
         done();
     });
+
+    it('should generate a new id when "defaultFn" is "guid"', function (done) {
+      var CustomModel = db.define('CustomModel', {
+        guid: { type: String, defaultFn: 'guid' }
+      });
+
+      var inst = CustomModel.create(function (err, m) {
+        m.guid.should.match(UUID_REGEXP);
+        done();
+      });
+    });
+
+    it('should generate a new id when "defaultfn" is "uuid"', function (done) {
+      var CustomModel = db.define('custommodel', {
+        guid: { type: String, defaultFn: 'uuid' }
+      });
+
+      var inst = CustomModel.create(function (err, m) {
+        m.guid.should.match(UUID_REGEXP);
+        done();
+      });
+    });
+
+    it('should generate current time when "defaultFn" is "now"', function (done) {
+      var CustomModel = db.define('CustomModel', {
+        now: { type: Date, defaultFn: 'now' }
+      });
+
+      var now = Date.now();
+      var inst = CustomModel.create(function (err, m) {
+        m.now.should.be.instanceOf(Date);
+        m.now.should.be.within(now, now + 200);
+        done();
+      });
+    });
+
     // it('should work when constructor called as function', function() {
     //     var p = Person({name: 'John Resig'});
     //     p.should.be.an.instanceOf(Person);