System.NullReferenceException發布為Azure時

Question

您好，我已經發布了我的網站，該網站在本地從Visual Studio到Azure都可以，現在每次嘗試訪問該頁面時，都會遇到以下異常。

[NullReferenceException: Object reference not set to an instance of an object.]
   WebApplication1.Logic.RoleActions.AddUserAndRole() +390
   WebApplication1.Global.Application_Start(Object sender, EventArgs e) +47

因為它指向Logic.RoleActions和Global.Application_Start，所以我將在其中發布代碼。

RoleActions

namespace WebApplication1.Logic
{
internal class RoleActions
{
    internal void AddUserAndRole()
    {
        // Access the application context and create result variables.
        Models.ApplicationDbContext context = new ApplicationDbContext();
        IdentityResult IdRoleResult;
        IdentityResult IdUserResult;

        // Create a RoleStore object by using the ApplicationDbContext object. 
        // The RoleStore is only allowed to contain IdentityRole objects.
        var roleStore = new RoleStore<IdentityRole>(context);

        // Create a RoleManager object that is only allowed to contain IdentityRole objects.
        // When creating the RoleManager object, you pass in (as a parameter) a new RoleStore object. 
        var roleMgr = new RoleManager<IdentityRole>(roleStore);

        // Then, you create the "canEdit" role if it doesn't already exist.
        if (!roleMgr.RoleExists("canEdit"))
        {
            IdRoleResult = roleMgr.Create(new IdentityRole { Name = "canEdit" });
        }

        // Create a UserManager object based on the UserStore object and the ApplicationDbContext  
        // object. Note that you can create new objects and use them as parameters in
        // a single line of code, rather than using multiple lines of code, as you did
        // for the RoleManager object.
        var userMgr = new UserManager<ApplicationUser>(new UserStore<ApplicationUser>(context));
        var appUser = new ApplicationUser
        {
            UserName = "canEditUser@wingtiptoys.com",
            Email = "canEditUser@wingtiptoys.com"
        };
        IdUserResult = userMgr.Create(appUser, "Pa$$word1");

        // If the new "canEdit" user was successfully created, 
        // add the "canEdit" user to the "canEdit" role. 
        if (!userMgr.IsInRole(userMgr.FindByEmail("canEditUser@wingtiptoys.com").Id, "canEdit"))
        {
            IdUserResult = userMgr.AddToRole(userMgr.FindByEmail("canEditUser@wingtiptoys.com").Id, "canEdit");
        }

        if (!userMgr.IsInRole(userMgr.FindByEmail("kasi64@seznam.cz").Id, "canEdit"))
        {
            IdUserResult = userMgr.AddToRole(userMgr.FindByEmail("kasi64@seznam.cz").Id, "canEdit");
        }
    }
}
}

和全球

namespace WebApplication1
{
public class Global : HttpApplication
{
    void Application_Start(object sender, EventArgs e)
        {
            // Code that runs on application startup
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);

            // Create the custom role and user.
            RoleActions roleActions = new RoleActions();
            roleActions.AddUserAndRole();



        }
    }
}

我不明白為什么它在本地可以正常工作，但是在發布時卻存在問題。 謝謝

Answer 1

NullReferenceException很可能是由userMgr.FindByEmail("xxx")調用之一引起的。 您不會處理userMgr.FindByEmail方法返回null的情況，而您直接訪問它的Id屬性。

Answer 2

我懷疑是因為在Azure中沒有用戶收到kasi64@seznam.cz的電子郵件。 因此，在此行上調用Id將引發空引用異常。

userMgr.FindByEmail("kasi64@seznam.cz").Id