Allow model.schema to be a function that returns the schema object

README.md

@@ -145,6 +145,8 @@ If a form has a model attached to it, the initial values are taken from the mode
 <a name="schema-definition"/>
 #Schema definition
 
+The schema defined on your model can be the schema object itself, or a function that returns a schema object. This can be useful if you're referencing variables that haven't been initialized yet.
+
 The following default editors are included:
 
 - [Text](#editor-text)

src/backbone-forms.js

@@ -329,13 +329,25 @@
      *          data    {Array} : Pass this when not using a model. Use getValue() to get out value
      *          fields  {Array} : Keys of fields to include in the form, in display order (default: all fields)
      */
-    initialize: function(options) {
-      this.schema = options.schema || (options.model ? options.model.schema : {}),
+    initialize: function(options) { 
+      //Get the schema
+      this.schema = (function() {
+        if (options.schema) return options.schema;
+
+        var model = options.model;
+        if (!model) throw new Error('Could not find schema');
+
+        if (_.isFunction(model.schema)) return model.schema();
+
+        return model.schema;
+      })();
+
+      //Handle other options
       this.model = options.model;
       this.data = options.data;
       this.fieldsToRender = options.fields || _.keys(this.schema);
       this.fieldsets = options.fieldsets;
-
+      
       //Stores all Field views
       this.fields = {};
     },

test/form.js

@@ -30,6 +30,24 @@ test("'schema' option - If not present, the 'schema' attribute on the model is u
     equal($('textarea', form.el).length, 1);
 });
 
+test('The schema on the model can be a function', function() {
+  var post = new Post,
+      _schema = post.schema;
+
+  post.schema = function() {
+    return _schema;
+  }
+
+  var form = new Form({
+    model: post
+  }).render();
+
+
+
+  //Stored correct schema object
+  equal(form.schema, _schema);
+});
+
 test("'model' option - Populates the form", function() {
     var post = new Post();