AJAX 发布请求不会发送 JSON 数据答案

【问题标题】：AJAX post request will not send JSON dataAJAX 发布请求不会发送 JSON 数据
【发布时间】：2011-06-07 18:07:37
【问题描述】：

在过去几个小时试图调试这个问题之后，我终于决定寻求帮助。

我有这样的数据，我想发送到 ashx 处理程序（这是大量数据）。

var value = [{"start":["3,0"],"block":["0,0","1,2"],"end":["2,1"],"star":"gold","moves":3,"difficulty":"easy"},{"start":["1,0"],"block":["1,3","3,0","4,2"],"end":["0,1"],"star":"gold","moves":4,"difficulty":"easy"},{"start":["3,0"],"block":["0,0","0,2","2,0","3,2"],"end":["1,0"],"star":"silver","moves":4,"difficulty":"easy"},{"start":["3,0"],"block":["0,0","2,0","3,1"],"end":["1,3"],"star":"gold","moves":6,"difficulty":"easy"},{"start":["0,0","2,0"],"block":["2,3"],"end":["1,2"],"star":"gold","moves":4,"difficulty":"easy"},{"start":["2,1"],"block":["0,1","0,2","1,0","1,1","2,0","2,2","2,3","3,1","3,2"],"end":["1,3"],"star":"gold","moves":5,"difficulty":"easy"},{"start":["1,0"],"block":["0,0","3,0","2,3"],"end":["4,1"],"star":"gold","moves":5,"difficulty":"medium"},{"start":["0,0","0,4"],"block":["0,5","0,2","3,3"],"end":["1,1"],"star":"gold","moves":7,"difficulty":"medium"},{"start":["0,0","2,6"],"block":["0,5","3,3","2,1"],"end":["3,5"],"star":"gold","moves":8,"difficulty":"medium"},{"start":["4,1","4,3"],"block":["3,0","4,2"],"end":["0,1","1,4","3,2"],"star":"gold","moves":8,"difficulty":"medium"},{"start":["1,2","3,4","4,2"],"block":["0,2","3,0"],"end":["2,3"],"star":"gold","moves":9,"difficulty":"medium"},{"start":["3,1","3,6"],"block":["0,0","0,3","0,7","2,5"],"end":["2,3"],"star":"gold","moves":11,"difficulty":"hard"},{"start":["0,7","0,2"],"block":["2,0","3,2","0,6","1,6","1,7"],"end":["3,3"],"star":"gold","moves":12,"difficulty":"hard"},{"start":["0,0","0,3"],"block":["0,1","2,2","3,0","3,3"],"end":["4,2"],"star":"gold","moves":8,"difficulty":"hard"},{"start":["0,0","0,6"],"block":["0,1","1,0","1,1","2,5","3,7"],"end":["3,4"],"star":"gold","moves":13,"difficulty":"hard"},{"start":["0,0","0,2","0,4","2,0","2,4","3,2","4,0","4,4"],"block":["0,1","0,3","1,0","1,1","1,2","1,3","1,4","2,1","2,3","3,0","3,1","3,3","3,4","4,1","4,2","4,3"],"end":["2,2"]},{"start":["0,0","0,2","0,4","1,1","2,0","2,4","3,2","4,0","4,2","4,4"],"block":["0,1","0,3","1,0","1,2","1,3","1,4","2,1","2,3","3,0","3,1","3,3","3,4","4,1","4,3"],"end":["2,2"],"star":"silver","moves":42,"difficulty":"medium"},{"start":["0,0","3,3","4,0"],"block":["0,1","2,3","3,0","4,4"],"end":["0,3"],"star":"gold","moves":11,"difficulty":"hard"},{"start":["0,4","1,1","3,5","4,2"],"block":["0,0","3,1","4,1"],"end":["2,3"],"star":"gold","moves":14,"difficulty":"hard"},{"start":["0,0","3,2","3,6"],"block":["0,4","0,5","4,4"],"end":["1,1"],"star":"gold","moves":13,"difficulty":"hard"},{"start":["0,2"],"block":["0,7","4,0","4,6","5,0","6,0","6,5"],"end":["2,0"]}]

我正在使用这个函数来发送请求：

function storeValue(value) {
    var val = encodeURIComponent(JSON.stringify(value));
    $.ajax({
        url: "DataHandler.ashx",
        async: false,
        data: { key: "someKey", value: val, action: "store" },
        datatype: "json",
        success: function (data) {
        }
    });
};

在DataHandler.ashx中，相关代码如下：

public class DataHandler : IHttpHandler, IReadOnlySessionState
    {
        public void ProcessRequest(HttpContext context)
        {
             var query = context.Request.QueryString;
             string action = query["action"];
             string key = query["key"];
             string val = query["value"];
        }
    }

通过调试，我发现 DataHander 甚至没有被调用。如果我从查询字符串中删除value，如下所示：

data: { key: key, action: "store" },

ProcessRequest 方法将按照我的预期被调用。

我猜value 可能太长了。为什么没有发送，我该如何解决？

【问题讨论】：

您是否尝试过通过 Fiddler 或 Firebug 监控您的请求？此外，将其设为 GET 可能会导致您遇到 URI + 查询字符串的最大长度，我认为这是 2000-4000 字符限制。我认为 IE8 有 2048 个限制。如果你通过 Fiddler 运行你的请求，你看到它被发送了吗？如果是这样，您在响应中看到了什么错误（如果有）？
为什么你没有在$.ajax 中添加type: "POST"？其他方式，我认为它确实 GET 请求，并且必须在一个字符串中给出数据，如下所示：var=val&var2=val2 等等......
@David 它有一个400 Bad Request 错误。
尝试将方法更改为 POST 看看会发生什么。如果这可行，您可能已达到 GET 长度限制。
@David 更改为 POST 并将 context.Request.QueryString 更改为 context.Request.Form 已修复，谢谢。你能发布一个我可以接受的答案吗？

标签： jquery ajax json ashx

【解决方案1】：

当我运行测试代码时，我看到 jQuery ajax 调用返回以下错误：

异常详情：System.Web.HttpException：长度此请求的查询字符串超出配置 maxQueryStringLength 值。

所以您的查询字符串太长（至少对于我正在测试的 IE9 而言）。

正如 cmets 建议的那样，将其更改为 POST 允许在您的 ASHX 文件中访问 ProcessRequest 方法。

您还想更改 ProcessRequest 以从请求正文中检索值，而不是从查询字符串中检索......

public void ProcessRequest(HttpContext context)
{
    var query = context.Request;
    string action = query["action"];
    string key = query["key"];
    string val = query["value"];
}

我希望这会有所帮助！

【讨论】：