从javascript调用webmethod时ASP.NET 500内部服务器错误 [英] ASP.NET 500 Internal Server Error while calling webmethod from javascript

问题描述

我正在尝试使用AJAX调用webmethod功能，但无法获得适当的结果.我已经搜索了我的问题，找到了许多解决方案，但是这些解决方案对我没有用.请指导我我在做什么错.帮助将不胜感激.

I'm trying to call the webmethod fucntionality using AJAX but unable to get the appropriate results. I have googled my problem and found many solution but those didn't worked for me. Please guide me what I'm doing wrong. Help will be appreciated.

欢呼

代码段

 function checkUserNameExists() {

//initialization
var pagePath = window.location.pathname + "/getUsername";
var value = document.getElementById('control_userName').value;
var dataString = "{ 'value':'" + value + "' }";
$.ajax({
    type: "GET",
    url: pagePath,
    data: dataString,
    contentType: "application/json; charset=utf-8",
    dataType: "json",
    error:
            function (XMLHttpRequest, textStatus, errorThrown) {

            },
    success:
            function (result) {
                var flag = true;
                if (result != null) {
                    flag = result.d;
                    if (flag == "True") {
                        alert('okay fine you are good');
                    }
                    else {
                        alert('try again');
                    }
                }
            }
});
 }

隐藏代码文件中的方法

    [WebMethod]
    [ScriptMethod(UseHttpGet = true)]
    public string getUsername(string value)
    {
        return "True";
    }

EXCEPTION

 ExceptionType: "System.InvalidOperationException"
  Message: "An attempt was made to call the method 'getUsername' using a        POST request, which is not allowed."

推荐答案

首先，如果web方法在页面类中，而不在Webservice类中，则它应该是静态的.

First, it the webmethod is in the page class, and not in a Webservice class, then it should be static.

第二，传输的数据实际上不是字符串，而是对象，因此将其更改为:

Second, the data transfered is not really a string, but an object, so change it to:

var dataString = { 'value':  value  };

第三件事，类型"用于旧版本的jquery，您应该将ajax调用更改为:

Third thing, "type" is for older versions of jquery, you should either change your ajax call to:

method: "GET",
url: pagePath,
data: dataString,
contentType: "application/json; charset=utf-8",
dataType: "json",...

或通过删除

UseHttpGet = true

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