我目前正在 Visual Studio Express 2013 for Web 中构建一个网站,并且使用默认的成员(member)功能供用户注册。但是,当我在本地主机上打开网站并尝试注册用户时,我收到以下错误:
An exception of type 'System.MissingMethodException' occurred in mscorlib.dll
but was not handled in user code
Additional information: Method not found: 'System.Threading.Tasks.Task`1<!!0>
System.Data.Entity.QueryableExtensions.FirstOrDefaultAsync(System.Linq.IQueryable`1<!!0>,
System.Linq.Expressions.Expression`1<System.Func`2<!!0,Boolean>>)'.
这是我的浏览器的堆栈跟踪:
[MissingMethodException: Method not found: 'System.Threading.Tasks.Task`1<!!0> System.Data.Entity.QueryableExtensions.FirstOrDefaultAsync(System.Linq.IQueryable`1<!!0>, System.Linq.Expressions.Expression`1<System.Func`2<!!0,Boolean>>)'.]
Microsoft.AspNet.Identity.EntityFramework.UserStore`6.GetUserAggregateAsync(Expression`1 filter) +0
Microsoft.AspNet.Identity.EntityFramework.UserStore`6.FindByNameAsync(String userName) +1071
Microsoft.AspNet.Identity.UserManager`2.FindByNameAsync(String userName) +177
Microsoft.AspNet.Identity.<ValidateUserName>d__4.MoveNext() +803
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +93
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +52
System.Runtime.CompilerServices.TaskAwaiter.GetResult() +21
Microsoft.AspNet.Identity.<ValidateAsync>d__0.MoveNext() +468
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +93
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +52
System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() +24
Microsoft.AspNet.Identity.CultureAwaiter`1.GetResult() +123
Microsoft.AspNet.Identity.<CreateAsync>d__0.MoveNext() +795
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +93
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +52
System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() +24
Microsoft.AspNet.Identity.CultureAwaiter`1.GetResult() +123
Microsoft.AspNet.Identity.<CreateAsync>d__d.MoveNext() +970
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +93
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +52
System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() +24
Microsoft.AspNet.Identity.AsyncHelper.RunSync(Func`1 func) +409
Microsoft.AspNet.Identity.UserManagerExtensions.Create(UserManager`2 manager, TUser user, String password) +260
Account_Register.CreateUser_Click(Object sender, EventArgs e) in c:\Users\Matthew\Documents\College\Senior\CSE 448\Capstone\Capstone\Account\Register.aspx.cs:14
System.Web.UI.WebControls.Button.OnClick(EventArgs e) +9628026
System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +103
System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +35
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1724
抛出异常的代码用星号标记:
protected void CreateUser_Click(object sender, EventArgs e)
{
var manager = new UserManager();
var user = new ApplicationUser() { UserName = UserName.Text };
*****IdentityResult result = manager.Create(user, Password.Text);
if (result.Succeeded)
{
IdentityHelper.SignIn(manager, user, isPersistent: false);
IdentityHelper.RedirectToReturnUrl(Request.QueryString["ReturnUrl"], Response);
}
else
{
ErrorMessage.Text = result.Errors.FirstOrDefault();
}
}
我已经搜索了一段时间,但似乎找不到解决方案。我尝试更新所有引用资料,但无济于事。还有其他人遇到过这种情况吗?
请您参考如下方法:
明白了! FirstOrDefaultAsync
扩展方法仅存在于 .Net 4.5 Entity Framework 程序集中。我在不同的项目中引用了 .Net 4.0 和 .Net 4.5 的混合体。当我将它们全部更改为 .Net 4.5 时,它可以使用 Async
代码。