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I have an ASP.Net Core and a Web Api Project in the same solution. I'm calling Get, Post, Put, Delete from my Core Project which is defined in my Api project. Definitely I need to enable CORS.

Bellow is the code that I added in my Web Api web.config file,

<httpProtocol>
  <customHeaders>
    <!-- Enable Cross Domain AJAX calls -->
     <clear />
          <add name="Access-Control-Allow-Origin" value="*" />
          <add name="Access-Control-Allow-Headers" value="Content-Type"/>
  </customHeaders>
</httpProtocol>

And my Ajax code from Core project,

$.ajax({
        "url": "myApiUrl",
        "type": "Get",
        "data": {
            //Here I'm passing a value
        },
         success: function (d) {
        }

I set both the projects as startup project. Not an issue. It's calling the Api method and returning the data. But some times it's not returning anything, even the method returns data, I'm getting the error in browser console that I mentioned in my question title. I checked many answers in SO, including this one, all said that I need to add access control in my response header. Any one tell me where I need to add exactly and what I need to add so that it will work as expected.

I checked with Asp.net MVC project too instead Core, same thing happened.

Note: I added CORS in my Web Api Project not in my Web Project.

Community
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Basanta Matia
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2 Answers2

1

I guess you have not correctly enabled CORS in Web API. You can do this by following process:

1) You can put [EnableCors] Attribute at the controller in Web API or globally in WebAPI Config.

Example - [EnableCors("*", "*", "*")]. Put this on the controller (for which you want to allow CORS). Note: You can modify attributes to this filter to allow certain methods, URLs etc

2) Call enableCors in WebAPi.config i.e. 

public static void Register(HttpConfiguration config)
  {
    // Other configuration omitted
    config.EnableCors();
  }

EDIT: If you need to Enable CORS globally, delete EnableCors attribute from controller and modify EnableCors() line in WebApiConfig.cs file to be :

config.EnableCors(new EnableCorsAttribute("*", "*", "*"));
Rohit Garg
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  • Though I want globally, that's why I added in web.config file. No issue. But where I need to write Register method ? – Basanta Matia May 12 '17 at 06:47
  • You don't need to write register method. It is already there in WebApiConfig.cs file in web api project. Its created by default. You just neeed to add the line inside it. – Rohit Garg May 12 '17 at 06:48
  • Currently I'm working on ASP.Net Core. There is no file called WebApiConfig.cs. I added in startup.cs file under Configure method. Saying, does not contain a definition for EnableCors. – Basanta Matia May 12 '17 at 07:01
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    For Asp.Net Core, this should help you : http://stackoverflow.com/questions/31942037/how-to-enable-cors-in-asp-net-core – Rohit Garg May 12 '17 at 07:25
0

Try this:

   public void ConfigureServices(IServiceCollection services)
{
    services.AddCors(o => o.AddPolicy("CrossPolicy", builder =>
    {
        builder.AllowAnyOrigin()
               .AllowAnyMethod()
               .AllowAnyHeader();
    }));

    // ...
}

For every request:

public void Configure(IApplicationBuilder app)
{
    app.UseCors("CrossPolicy");

    // ...
}

OR

[EnableCors("CrossPolicy")]

You can find more information in this and this link.

Hopefully it's help for you.

Ashiquzzaman
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  • There is no ApplicationOAuthProvider class or MatchEndpoint in my application. Do I need to add those or what ? If I need to add then where I need to add ? – Basanta Matia May 12 '17 at 05:31
  • I update my answer. And sorry for my previous answer. that is for ASP.NET web api 2@BasantaMatia – Ashiquzzaman May 12 '17 at 08:43