从javascript调用webmethod时，ASP.NET 500内部服务器出错

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.

我试图使用AJAX调用webmethod fucntionality但无法获得适当的结果。我搜索了我的问题并找到了许多解决方案，但那些对我没用。请指导我做错了什么。帮助将不胜感激。

Cheers

干杯

Code Snippet

代码片段

 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');
                    }
                }
            }
});
 }

Method in Behind Code file

代码文件后面的方法

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

EXCEPTION

例外

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

4 个解决方案

#1

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

首先，webmethod是在页面类中，而不是在Webservice类中，那么它应该是静态的。

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

其次，传输的数据实际上不是字符串，而是一个对象，因此将其更改为：

var dataString = { 'value':  value  };

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

第三件事，“类型”是旧版本的jquery，您应该将ajax调用更改为：

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

Or change the function in the server side to get post calls, by removing the

或者通过删除，更改服务器端的功能以获得发布呼叫

UseHttpGet = true

#2

Probably you need to add static to your method declaration as below

您可能需要在方法声明中添加静态，如下所示

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

if this isn't the case, you could F12 the browser->network then click on the error message to see it briefly.

如果不是这种情况，您可以使用F12浏览器 - >网络，然后单击错误消息进行简要查看。

Concerning the reported issue,the problem with get request, try to make it post

关于报告的问题，get请求的问题，尽量让它发布

#3

The Answer is here :link

答案在这里：链接

the problem is with the annotation I was using the [ScriptMethod(UseHttpGet = true)] which causing the error. just change the value from true to false.

问题在于我使用的[ScriptMethod（UseHttpGet = true）]注释会导致错误。只需将值从true更改为false。

#4

This is not specific to this question but you can check a few things to get better understanding of what is causing the issue.

这不是特定于这个问题，但你可以检查一些事情，以更好地了解导致问题的原因。

Check the status code and type of request in the General section of Request Headers.
在“请求标头”的“常规”部分中检查请求的状态代码和类型。
Check the Response Headers if there is any json error.
如果有任何json错误，请检查响应标头。
Check the Response to get the message, stacktrace and exception type.
检查响应以获取消息，堆栈跟踪和异常类型。
Check the Request Payload section in Headers for parameters passed.
检查Headers中的Request Payload部分是否已传递参数。

Check this post for more detail.

查看此帖子了解更多详情。

#1