Backbone.Model File Upload

A concise, non-iframe, & pure XHR2/AJAX Backbone.model file upload. (Good for IE >= 10, FF, Chrome.)

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

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

model.save([file attribute], [file object], [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" />).

File, Blob, and FileList are all valid in the model. Once set it will be uploaded when ready.

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', function(evt) { console.log(evt) });
// Will result: with an event object you can use evt.loaded and evt.total to figure out the 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.

To see how to support file uploads for .NET, see this good link: http://www.asp.net/web-api/overview/working-with-http/sending-html-form-data,-part-2

For java, there's a great example here using the Spring framework: http://viralpatel.net/blogs/spring-mvc-multiple-file-upload-example/

Included here is a "node" js mock file server so you can use to test.

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';

Remember, you would need to "unflatten" the model in the back-end. If you are a "node" user, please see my "mock-file-server" to see what I did there to "unflatten" the model. After the file has been Posted (or Put), send the "unflattened" version back to the client. That way, the Backbone Model will be in sync. Also remember, nested arrays are parsed as objects, so its advised that you don't have nested arrays. The warnings can go on and on. Basic rule, try to avoid nesting if you can.

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" />

Revisions

c Version v0.1

• First release

Version v0.2

• Reformatted to standard AMD boilerplate pattern

Version v0.3

• Fixed the use of "attrs" instead of using "this.attributes" at condition check and model parsing/flattening
• Added the option to save just option, i.e: .save({ silent: true });

Version 0.4

• Fixed all the wonkiness from 0.3 with the attributes and save. Reverted a lot of code and refactored
• Added "blob" support as a FileObj entity
• Added some Jasmine tests

Version 0.5

• Added FileList support

Version 0.5.1

• Fix refactoring error.

Version 0.5.2

• Add jQuery to the UMD dependency model

Version 0.5.3

• Added CommonJS support

Version 1.0.0

• Sticking to a semantic versioning pattern
• Fixed CommonJS argument mess up
• Switching to "Bracket" notation for flattening nested objects
• Added an "unflatten" internal method to unflatten

Dev/Installation

If you want to work on this plugin, test it, etc., it just needs an install of node and grunt.

npm i -d

To build

grunt build

To test

npm test OR grunt test