为什么我从Membership.GetCurrentUserName得到NullReferenceException? [英] Why am I getting a NullReferenceException from Membership.GetCurrentUserName?

问题描述

我刚改用msbuild来预编译我的网站，现在我遇到了这个奇怪的错误:

I've just switched to using msbuild to precompile my website and now I'm getting this strange error:

我有一个对Membership.GetUser()的调用，它引发:

I have a call to Membership.GetUser() which throws:

[NullReferenceException: Object reference not set to an instance of an object.]
System.Web.Security.Membership.GetCurrentUserName() +36
System.Web.Security.Membership.GetUser() +7
...

推荐答案

Reflector显示Membership.GetCurrentUserName的实现是:

Reflector shows the implementation of Membership.GetCurrentUserName is:

private static string GetCurrentUserName()
{
    if (HostingEnvironment.IsHosted)
    {
        HttpContext current = HttpContext.Current;
        if (current != null)
        {
            return current.User.Identity.Name;
        }
    }
    IPrincipal currentPrincipal = Thread.CurrentPrincipal;
    if ((currentPrincipal != null) && (currentPrincipal.Identity != null))
    {
        return currentPrincipal.Identity.Name;
    }
    return string.Empty;
}

乍一看，最可能的解释是:

At first glance the most likely explanation is that:

• HttpContext.Current不为null，并且

• HttpContext.Current is not null, and

HttpContext.Current.User为null或具有空的Identity属性.

HttpContext.Current.User is null or has a null Identity property.

所有其他路径似乎都对null进行了测试.

All other paths seem to have a test for null.

所以我建议您跟踪HttpContext.User的类型和内容.

So I suggest you trace the type and contents of HttpContext.User.

HttpContext.Current.User是一个IPrincipal，我所知道的IPrincipal的大多数具体实现都不允许使用null身份，因此我押注HttpContext.User为null.

HttpContext.Current.User is an IPrincipal, and most concrete implementations of IPrincipal that I know of don't allow a null identity, so I'd bet on HttpContext.User being null.

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