MVC6 Cors - intercept preflight

问题

I'm upgrading my WebApi(s) to MVC6.

In WebApi I could intercept every HTTP request and if it was a preflight I could respond with headers the browser would accept.

I'm trying to figure out how to do the same thing in MVC6 WebApi.

Here is the WebApi code.

    protected void Application_BeginRequest(object sender, EventArgs e)
    {
        if (Context.Request.Path.Contains("api/") && Context.Request.HttpMethod == "OPTIONS")
        {
            Context.Response.AddHeader("Access-Control-Allow-Origin", Context.Request.Headers["Origin"]);
            Context.Response.AddHeader("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
            Context.Response.AddHeader("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS");
            Context.Response.AddHeader("Access-Control-Allow-Credentials", "true");
            Context.Response.End();
        }
    }

How do I do the same thing with MVC6?

Thanks, Bob

Here is my next attempt based on feedback. I could probably figure this out on my own if I understood the middleware pipeline. I'll learn it now of course.

I tried this code but it's not hit on http requests as I had hoped.

    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        // Configure the HTTP request pipeline.
        app.UseStaticFiles();

        // Add MVC to the request pipeline.
        app.UseMvc();
        // Add the following route for porting Web API 2 controllers.
        // routes.MapWebApiRoute("DefaultApi", "api/{controller}/{id?}");

        // custom middleware to checked each call as it comes in.
        app.Use(async (httpContext, next) =>
        {
            if (httpContext.Request.Path.Value.Contains("api/") && httpContext.Request.Method == "OPTIONS")
            {
                httpContext.Response.Headers.Add("Access-Control-Allow-Origin", new[] { httpContext.Request.Headers["Origin"] });
                httpContext.Response.Headers.Add("Access-Control-Allow-Headers", new[] { "Origin, X-Requested-With, Content-Type, Accept" });
                httpContext.Response.Headers.Add("Access-Control-Allow-Methods", new[] { "GET, POST, PUT, DELETE, OPTIONS" });
                httpContext.Response.Headers.Add("Access-Control-Allow-Credentials", new[] { "true" });
                return;
            }
            await next();
        });

    }

回答1:

You can add your own middleware for that. Here is a quick example adding it inline, but you could also encapsulate in a class:

app.Use(async (httpContext, next) =>
{
    if (httpContext.Request.Path.Value.Contains("api/") && httpContext.Request.Method == "OPTIONS")
    {
        httpContext.Response.Headers.Add("Access-Control-Allow-Origin", new[] { httpContext.Request.Headers["Origin"] });
        httpContext.Response.Headers.Add("Access-Control-Allow-Headers", new[] { "Origin, X-Requested-With, Content-Type, Accept" });
        httpContext.Response.Headers.Add("Access-Control-Allow-Methods", new[] { "GET, POST, PUT, DELETE, OPTIONS" });
        httpContext.Response.Headers.Add("Access-Control-Allow-Credentials", new[] { "true" });
        return;
    }
    await next();
});

You will probably also want to keep an eye on the ongoing work to support cors within the ASP 5 framework

来源：https://stackoverflow.com/questions/31976337/mvc6-cors-intercept-preflight

标签

cors

asp.net-core-mvc

preflight