c# - 发布到 azure 时出现 System.NullReferenceException

Question

您好，我已经发布了我的网站，该网站可以在本地从 Visual Studio fork 到 Azure，现在每次我尝试访问该页面时都会遇到以下异常。

[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

因为它指向 Logic.RoleActions 和 Global.Application_Start，我将在其中发布代码。

角色操作

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 = "<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="9efdfff0dbfaf7eacbedfbecdee9f7f0f9eaf7eeeaf1e7edb0fdf1f3" rel="noreferrer noopener nofollow">[email protected]</a>",
            Email = "<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="a8cbc9c6edccc1dcfddbcddae8dfc1c6cfdcc1d8dcc7d1db86cbc7c5" rel="noreferrer noopener nofollow">[email protected]</a>"
        };
        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("<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="7112101f34151805240214033106181f16051801051e08025f121e1c" rel="noreferrer noopener nofollow">[email protected]</a>").Id, "canEdit"))
        {
            IdUserResult = userMgr.AddToRole(userMgr.FindByEmail("ca<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="3e507b5a574a6b4d5b4c7e495750594a574e4a51474d105d5153" rel="noreferrer noopener nofollow">[email protected]</a>").Id, "canEdit");
        }

        if (!userMgr.IsInRole(userMgr.FindByEmail("<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="cba0aab8a2fdff8bb8aeb1a5aaa6e5a8b1" rel="noreferrer noopener nofollow">[email protected]</a>").Id, "canEdit"))
        {
            IdUserResult = userMgr.AddToRole(userMgr.FindByEmail("<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="7b101a08124d4f3b081e01151a16551801" rel="noreferrer noopener nofollow">[email protected]</a>").Id, "canEdit");
        }
    }
}
}

和全局

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();



        }
    }
}

我不明白为什么它在本地运行良好，但发布时却出现问题。谢谢

Answer 1

NullReferenceException 很可能是由 userMgr.FindByEmail("xxx") 调用之一引起的。您不处理 userMgr.FindByEmail 方法返回 null 的情况，而是直接访问它的 Id 属性。