小编Dav*_*ave的帖子

在MVC 5模板中实现Facebook登录，已添加了应用ID和密码。

最初登录失败，因为它返回null

public async Task<ActionResult> ExternalLoginCallback(string returnUrl)
{
    // Crashes on this line
    var loginInfo = await AuthenticationManager.GetExternalLoginInfoAsync();
    if (loginInfo == null)
    {
        return RedirectToAction("Login");
    }
}

搜索后遇到一个解决方案，该解决方案说用此替换现有的ExternalLoginCallback方法

[AllowAnonymous]
    public async Task<ActionResult> ExternalLoginCallback(string returnUrl)
    {
        var result = await AuthenticationManager.AuthenticateAsync(DefaultAuthenticationTypes.ExternalCookie);
        if (result == null || result.Identity == null)
        {
            return RedirectToAction("Login");
        }

        var idClaim = result.Identity.FindFirst(ClaimTypes.NameIdentifier);
        if (idClaim == null)
        {
            return RedirectToAction("Login");
        }

        var login = new UserLoginInfo(idClaim.Issuer, idClaim.Value);
        var name = result.Identity.Name == null ? "" : …