Ajax获取对ASP.NET MVC控制器的调用被视为“ NO'Access-Control-Allow-Origin'错误

Question

I am having a ajax call in view script. From this ajax call i am trying to get the data from controller action in same website. This is triggered as Cross No 'Access-Control-Allow-Origin' problem .

Java script code looks like

function displaydata(id) {
$.ajax({
    type: "GET",
    async: true,
    url: '@Url.Action("GetSomeData", "MyData")',
    contentType: "application/json; charset=utf-8",
    data: "id=" + id,
    dataType: "json",
    error: function (request, error) {

    },
    success: function (response) {
      alert(response);
    }
  });

My MyDataController.cs looks like

public class MyDataController : Controller
{
    [HttpGet]
    public string GetSomeData(int id)
    {  
        // converted object to json string e.g. into jsonString
        return jsonString;
    }
}

This is working fine on local machine but after deployment actual site does not work. I receive the error No 'Access-control-allow-origin' found in header.

My question is that I am calling same server controller from which page is served so how it becomes the candidate for CORS issue? And how to solve it? as a technology I have website built in ASP.NET MVC razor view with Ajax and jquery.

I did some more tests and found that if I deploy the WebSite in IIS in One of the VM it's working. When I deploy it to cloud Web Apps then I get the same issue.

Answer 1

This helped me, although I don't do why some request from the same domain were getting blocked, just like yours.

if (Request.UserHostName == "127.0.0.1")
{
    Response.AddHeader("Access-Control-Allow-Origin", "*");
}

Answer 2

Add this lines into your web config file... And if it doesn't work let me know

 <system.webServer>
    <httpProtocol>
        <customHeaders>
            <add name="Access-Control-Allow-Origin" value="*" />
            <add name="Access-Control-Allow-Methods" value="*" />
            <add name="Access-Control-Allow-Headers" value="*" />
        </customHeaders>
    </httpProtocol>
    <validation validateIntegratedModeConfiguration="false" />
   <modules runAllManagedModulesForAllRequests="true">
       <remove name="WebDAVModule" />
  </modules>
    <handlers>
        <remove name="ExtensionlessUrlHandler-Integrated-4.5" />
        <add name="ExtensionlessUrlHandler-Integrated-4.5" path="*." verb="*" type="System.Web.Handlers.TransferRequestHandler" resourceType="Unspecified" requireAccess="Script" preCondition="integratedMode,runtimeVersionv4.5" />
        <remove name="WebDAV" />
    </handlers>
</system.webServer>