骨干模型保存状态

I use backbone model to save the data to the server. then I handle the success or error callback after save(post) and set wait:true. my question is why backbone model only trigger the error callback when server returns a string? when server returns a json or any number, it will go to the success. the problem is if I want to return a multiple error message and I want to put all error message into a collection(json), it will never go to error callback. sample code like

echo 'success'; //actually it will go to error callback cuz it return a string(any string)
echo json_encode($some_array); // it will go to success
echo 200/anynumber; // it will go to sucess

My solution is if I wanna return a multiple message, I can separate those message by a delimiter, and use javascript native function split to separate them. is there any better solution like maybe I can return a state(indicate either success or error) and a collection from server?

model code looks like:
somemodel.save({somedata},
    {
        success:function(a,b,c){}, 
        error:function(b,c,d){},
        wait: true
    });

Backbone expects JSON as the default response format. When you get an integer, i suspect, backbone is using jquery $.parseJSON() on the number and returns it as valid JSON while it is not. If you want to return multiple errors messages, i suggest you put them into separate fields of an array and encode them then send as response to backbone.

EDIT

Just checked backbone source code and it doesn't call on $.parseJOSN() contrary to what was guessed above.

EDIT 2

Assume you have the following PHP code (as much as I would like to create a framework agnostic example, it is possible but things will be quicker and smoother using a framework so I have picked Slim).

When you save a model, backbone sends the data to the server using POST as the method. In Slim this will translate into the following:

$app = new \Slim\Slim();
$app->post('/authors/', function() use($app) {
    // We get the request data from backbone in $request
    $request = $app->request()->getBody();
    // We decode them into a PHP object
    $requestData = json_decode($request);
    // We put the response object in $response : this will allow us to set the response data like header values, etc
    $response = $app->response();

    // You do all the awesome stuff here and get an array containing data in $data //

    // Sample $data in case of success
    $data = array(
        'code' => 200,
        'status' => 'OK',
        'data' => array('id'=>1, 'name' => 'John Doe')
    );

    // sample $data in case of error
    $data = array(
        'code' => 500,
        'status' => 'Internal Server Error',
        'message' => 'We were unable to reach the data server, please try again later'
    );

    // Then you set the content type
    $app->contentType('application/json');
    // Don't forget to add the HTTP code, Backbone.js will call "success" only if it has 2xx HTTP code
    $app->response()->status( $data['code']);
    // And finally send the data
    $response->write($data);

I have used Slim simply because it gets the job done and everything should read like English.

As you can see, Backbone will need the response in JSON format. I just tested on one of my websites, if you send an HTTP code different from 2xx, Backbone will actually call error instead of success. But the browser will also catch that HTTP code, so watch out!

REMOVED INFO

Backbone parse function will be expecting JSON as well! Assume we have this collection:

var AuthorsCollection = Backbone.Collection.extend({
    initialize: function( models, options ) {
        this.batch = options.batch
    },

    url: function() {
        return '/authors/' + this.batch;
    },

    // Parse here allows us to play with the response as long as "response" is a JSON object. Otherwise, Backbone will automatically call the "error" function on whatever, say view, is using this collection.
    parse: function( response ) {
        return response.data;
    }
});

parse allows you to inspect the response, but will not accept anything else than JSON!