如何确定json对象是否为序列化字典？

Question

My application making an ajax POST to server, and if the server validation fails, server returns string or Dictionary<string, object> back to client.

So if server is sending Dictionary then the serialized responseText that jQuery is receiving something like

"{\"Key1\":[\"Error Message 1\"],\"Key2\":[\"Error message 2\"]}"

i also have corresponding responseJSON available on client side.

    $.ajax({
        cache: false,
        type: 'POST',
        url: url,
        data: data            
    })            
    .fail(function (response, textStatus, errorThrown) {           
            if (response.status === '400') {
                if ($.isArray(response.responseJSON)) {
                    $.each(response.responseJSON, function (index, value) {
                        //do something
                    })
                }
                else if ($.type(response.responseJSON) === 'string') {
                      // do something
                }
            }               
        }

The .isArray method returns false when response is dictionary. How do i determine if responseJSON is Dictionary and how do i loop?

Note
object that server is sending back

Answer 1

You try to interpret the response and see if it ends up being an object (or "Dictionary"). If the response appears to be JSON, and the result of it is also an object ("Dictionary"), then you know the string was an object ("Dictionary").

The code below should outline all necessary techniques for you to integrate it into your own code.

var thatResponseJson = "{\"Key1\":[\"Error Message 1\"],\"Key2\":[\"Error message 2\"]}";
try {
    var result = JSON.parse(thatResponseJson);
    if (result instanceof Array) {
        // An Array
    } else if (typeof result === 'object' && thatResponseJson[0] === '{') {
        // Usually an object
    } else if (typeof result === 'string') {
        // A string
    } else {
        // Neither an Array, some other kind of object, or a string
    }
} catch (err) {
    // Not valid JSON
}