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.
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` is being sent as the browser sends chunks of data. The `progress` trigger sends a progress status in percents.
```js
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.
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.
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.
