jQuery getJSON回调函数未在asp.net mvc jsonresult上触发，但在twitter json api上有效

问题描述

从子域调用json api似乎是什么问题?

What seems to be the problem calling the json api from a subdomain?

Asp.net MVC操作

Asp.net MVC Action

        [AllowAnonymous]
        [OutputCache(NoStore = true, Duration = 0, VaryByParam = "*")]
        public JsonResult getBalances()
        {
            var balances = new[]
                               {
                                   new {Id = 1, Balance = 3},
                                   new {Id = 2, Balance = 2},
                                   new {Id = 3, Balance = 1}
                               };
            return Json(balances, JsonRequestBehavior.AllowGet);
        }

jquery代码

var url = "http://subdomain.mysite.com/getBalances/";

$.getJSON(url + '?callback=?', function (data) {
           alert(data);
        });

但是如果我使用twitter api url，以上脚本将起作用:

But the above script works if I used the twitter api url:

var url = "https://api.twitter.com/1/statuses/user_timeline.json?include_entities=true&include_rts=true&screen_name=twitterapi&count=2";

json响应为:[{"Id":1,"Balance":3},{"Id":2,"Balance":2},{"Id":3,"Balance":1}]

The json response is:[{"Id":1,"Balance":3},{"Id":2,"Balance":2},{"Id":3,"Balance":1}]

推荐答案

我怀疑您违反了相同来源政策.该代码可与Twitter一起使用，因为Twitter支持 JSONP ，而您的控制器操作仅返回JSON.

I suspect that you are violating the same origin policy. The code works with Twitter because Twitter supports JSONP, whereas your controller action simply returns JSON.

如果导航到http://api.twitter.com/1/statuses/user_timeline.json?include_entities=true&include_rts=true&screen_name=twitterapi&count=2&callback=abc，您会注意到JSON响应是如何与您作为查询字符串参数提供的callback包装在一起的:

If you navigate to http://api.twitter.com/1/statuses/user_timeline.json?include_entities=true&include_rts=true&screen_name=twitterapi&count=2&callback=abc you wil notice how the JSON response is wrapped with the callback that you provided as query string parameter:

abc([...])

如果要在网站上实现相同目标，则应返回JSONP.这是您可以使用的自定义JSONP操作结果的示例:

If you want to achieve the same with your site you should return JSONP. Here's an example of a custom JSONP action result that you could use:

public class JsonpResult : ActionResult
{
    private readonly object _obj;

    public JsonpResult(object obj)
    {
        _obj = obj;
    }

    public override void ExecuteResult(ControllerContext context)
    {
        var serializer = new JavaScriptSerializer();
        var callbackname = context.HttpContext.Request["callback"];
        var jsonp = string.Format("{0}({1})", callbackname, serializer.Serialize(_obj));
        var response = context.HttpContext.Response;
        response.ContentType = "application/json";
        response.Write(jsonp);
    }
}

，您的控制器操作将变为:

and your controller action becomes:

[AllowAnonymous]
[OutputCache(NoStore = true, Duration = 0, VaryByParam = "*")]
public JsonResult getBalances()
{
    var balances = new[]
    {
        new { Id = 1, Balance = 3 },
        new { Id = 2, Balance = 2 },
        new { Id = 3, Balance = 1 }
    };
    return new JsonpResult(balances);
}

和通话:

var url = "http://subdomain.mysite.com/getBalances/";
$.getJSON(url + '?callback=?', function (data) {
    alert(data);
});

这篇关于jQuery getJSON回调函数未在asp.net mvc jsonresult上触发，但在twitter json api上有效的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！