Backbone.Model File Upload

A concise, non-iframe, & pure XHR2/AJAX Backbone.model file upload. (Good for IE >= 9, FF, Chrome.)

This plugin upgrades the current save method to be able to upload files using the HTML5's File API and FormData class.

NOTE: This plugin will require deep parsing in the back-end since it won't be using a JSON object. In other words, your normal JSON serialization won't work here. It will convert the model to a key/value pattern. Model will be flattened on request.

How to use

Grab the File object from the DOM, set it to an attribute, then call save. That's it! (save with the attribute parameter works as well)

model.save([file attribute], [file object], [options]);

model.set('file', [file object]);
model.save({}, [options])

set & save

model.set( [file attribute], [file object], [options] )

model.save( [file attribute], [file object], [options] )

In terms of how to use these methods, they have not changed. The only difference is that it has the capability to take a File object grabbed from the DOM (i.e. <input type="file" />).

As the file is being uploaded, a trigger progress fires as the browser sends chunks of data. The progress trigger sends a progress status in percents.

If you want to force not using FormData, add the option { formData: false } and the whether or not you have a file object in the model, it'll try to send it as part of the JSON object. Opposite is true (for whichever circumstance) is that if you set { formData: true }, it will force the usage of FormData. Not setting it will leave it automatic and it'll try to detect if there is the file in the model.

var fileObject = $(':input[type="file"]')[0].files[0];

var Email = Backbone.Model.extend({ url: 'upload.php', fileAttribute: 'attachment' });
var email = new Email();

email.set('from',       'me@somewhere.com');
email.set('to',         'somebody@somewhere.com');
email.set('subject',    'Greetings!');
email.set('body',       'Just wanted to say hello. Yours truly');
email.set('attachment', fileObject);

email.save();

email.on('progress', console.log);
// Will result: the status in percent i.e. 0.3233

fileAttribute

model.fileAttribute = [attribute]

The attribute file is the default. As you can see from the example above, you can set it to whatever you want.

How it works

This plugin will use the FormData class to wrap all the attributes in. That basically means it's making what we used to know as the old-fashioned "form" into a data object. The old-fashion "form" only took key-value pairs, so the same applies here. The attributes gets converted into a FormData object then is sent through as a "multipart/data-form". So it is recommended to use a flattened model for easier parsing as Jeremy Ashkenas himself usually recommends for all scenarios.

What happens to a model with nested objects/arrays?

The model will be flattened and the nested value will be separated with it's own unique composite "breadcrumb" key. The key parsing will reflect the array or object with the index or property respectively.

var obj = {
  'family': 'The Smiths',
  'grandpa': {
    'name': 'Ole Joe Smith',
    'children': [
      {
        'name': 'Mary Lee',
        'spouse': 'John Lee',
        'children': [
          {
            'name': 'Tiny Lee'
          }
        ]
      },
      {
        'name': 'Susan Smith'
      }
    ]
  }
}

Will parse into

obj['family']                             => 'The Smiths';
obj['grandpa.name']                       => 'Ole Joe Smith';
obj['grandpa.children.0.name']            => 'Mary Lee'; 
obj['grandpa.children.0.spouse']          => 'John Lee';
obj['grandpa.children.0.children.0.name'] => 'Tiny Lee';
obj['grandpa.children.1.name']            => 'Susan Smith'; 

Non-destructive plugin

The plugin is non-destructive to the existing behaviors. When a file object is detected, then the method is tweaked and converted to a FormData object.

Prerequisites

• jQuery
• Backbone v1.0
• Underscore v1.4

How to load

Require.js AMD

requirejs.config({
  paths: {
    'jquery': 'assets/js/jquery',
    'underscore': 'assets/js/underscore',
    'backbone': 'assets/js/backbone',
    'backbone-model-file-upload': 'assets/js/backbone-model-file-upload'
  },

  shim: {
    'backbone': {
      deps: ['underscore'],
      exports: 'Backbone'
    },
    'backbone-model-file-upload': {
      deps: ['jquery', 'underscore', 'backbone'],
      exports: 'Backbone'
    }
  }
});

Static

<script src="assets/js/jquery.js" />
<script src="assets/js/underscore.js" />
<script src="assets/js/backbone.js" />
<script src="assets/js/backbone-model-file-upload.js" />