c# – 在asp net中从facebook获取用户电子邮件

我正在尝试从Facebook获取用户名和用户电子邮件.我阅读了很多关于这个主题的信息,这是我的最终代码,仅在我的facebook app管理员帐户上有效：

public partial class Startup
{
    public void ConfigureAuth(IAppBuilder app)
    {

        /*Other external login options*/

         var FacebookOptions = new FacebookAuthenticationoptions()
                {
                    AppId = "My App Id",AppSecret = "My App Secret",SignInAsAuthenticationType = DefaultAuthenticationTypes.ExternalCookie,BackchannelHttpHandler = new FacebookBackChannelHandler(),UserinformationEndpoint = "https://graph.facebook.com/v2.7/me?fields=id,name,email"
                };


    }
}
public class FacebookBackChannelHandler : httpclienthandler
{
    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request,System.Threading.CancellationToken cancellationToken)
    {
        if (!request.RequestUri.AbsolutePath.Contains("/oauth"))
        {
            request.RequestUri = new Uri(request.RequestUri.AbsoluteUri.Replace("?access_token","&access_token"));
        }

        return await base.SendAsync(request,cancellationToken);
    }
}
public class AccountController : Controller
{
    public async Task<ActionResult> ExternalLoginCallback(string returnUrl)
    {
        var loginInfo = await AuthenticationManager.GetExternalLoginInfoAsync();
        /*my sign in code that works on my facebook app admin account*/
    }  
}

在每个帐号我得到loginInfo.Email等于null.

在developers.facebook.com我有：

当有人点击“使用Facebook登录”时,他会收到以下消息：

如果我点击“查看您提供的信息”,我会得到：

我错过了什么？为什么不起作用？

解决方法

终于找到了答案！所有需要做的就是将Scope = {“email”}添加到FacebookOptions,这就解决了这个问题！

我的代码现在：

public partial class Startup
{
    public void ConfigureAuth(IAppBuilder app)
    {

        /*Other external login options*/

         var FacebookOptions = new FacebookAuthenticationoptions()
                {
                    AppId = "My App Id",Scope = { "email" },email"
                };
    }
}

其余代码保持不变.如果此问题返回,我只为案例添加了错误页面：

public class AccountController : Controller
{
    public async Task<ActionResult> ExternalLoginCallback(string returnUrl)
    {
        var loginInfo = await AuthenticationManager.GetExternalLoginInfoAsync();
        if(loginInfo.Email == null)
        {
             return RedirectToAction("FacebookError","Account");
        }
        /*my sign in code*/
    }  
}