Question

HTTP PUT isn’t entirely cross browser so Rails (I’m using Rails 3) supports using POST and passing the _method query param. This is great, but it doesn’t seem to work when sending JSON.

Example:

$.ajax({
    url: window.location.pathname,
    type: 'POST',
    contentType: 'application/json',
    data: JSON.stringify({_method:'PUT', page:{my_data: 1}),
    dataType: 'json'
});

When Rails sees this, it doesn’t recognize the ‘_method’ override because it’s passed in the JSON format (perhaps that conversion is later?). Rails returns an error “No route matches …” saying it can’t find the route (to the resource), I assume because it doesn’t match the REST update=HTTP PUT verb, I’ve even tried appending this to the URL: ?_method=PUT but got the same result.

The only thing that does seem to work is setting an HTTP header:

$.ajax({
    url: window.location.pathname,
    type: 'POST',
    contentType: 'application/json',
    data: JSON.stringify({my_data: 1}),
    dataType: 'json',
    beforeSend: function(xhr){
        xhr.setRequestHeader("X-Http-Method-Override","put");
    }
});

Is setting the HTTP override header the best way?

Answer 1

AJAX supports the PUT verb directly so why bothering with _method and custom HTTP headers:

$.ajax({
    url: window.location.pathname,
    type: 'PUT',
    contentType: 'application/json',
    data: JSON.stringify({ page: { my_data: 1 }),
    dataType: 'json'
});

Also make sure you are respecting the same origin policy or jquery might try to use JSONP which works only with GET verbs.