播种会员用户会引发空引用异常答案

【问题标题】：Seeding a membership user throws null reference exception播种会员用户会引发空引用异常
【发布时间】：2014-03-17 13:33:57
【问题描述】：

使用 MVC5 和 EF6，我试图通过从 AccountController 注册操作复制代码来创建虚拟用户帐户，如下所示：

class SampleData : DropCreateDatabaseAlways<EFDbContext>
{
 public Microsoft.AspNet.Identity.UserManager<ApplicationUser> UserManager { get; private set; }

protected override void Seed(EFDbContext context)
    {

        base.Seed(context);
        var user = new ApplicationUser() { UserName = "Candidate1", AboutSelf = "", FirstName = "Candidate1",LastName="Candidate1",Sex=SexType.Unspecified,Id= Guid.NewGuid().ToString() };
         UserManager.CreateAsync(user, "Candidate1");
...

在上面的代码中，添加了一些自定义配置文件属性，我已经填充了所有属性，但仍然出现空引用异常：

at TestPro.WebUI.SampleData.Seed(EFDbContext context) in d:\Users\Arvind\Documents\Visual Studio 2013\Projects\TestPro\TestPro.WebUI\Models\SampleData.cs:line 22
at System.Data.Entity.DropCreateDatabaseAlways`1.InitializeDatabase(TContext context)
at System.Data.Entity.Internal.InternalContext.<>c__DisplayClasse`1.<CreateInitializationAction>b__d()
at System.Data.Entity.Internal.InternalContext.PerformInitializationAction(Action action)
at System.Data.Entity.Internal.InternalContext.PerformDatabaseInitialization()
at System.Data.Entity.Database.Initialize(Boolean force)
at TestPro.WebUI.MvcApplication.Application_Start() in d:\Users\Arvind\Documents\Visual Studio 2013\Projects\TestPro\TestPro.WebUI\Global.asax.cs:line 17

【问题讨论】：

标签： entity-framework asp.net-membership asp.net-mvc-5 seeding

【解决方案1】：

知道了，我错过了在使用前初始化 UserManager 属性

class SampleData : DropCreateDatabaseAlways<EFDbContext>
{
public Microsoft.AspNet.Identity.UserManager<ApplicationUser> UserManager { get; private set; }

protected override void Seed(EFDbContext context)
{
//Need to initialize UserManager property
UserManager = new UserManager<ApplicationUser>(new UserStore<ApplicationUser>(context));
    base.Seed(context);
    var user = new ApplicationUser() { UserName = "Candidate1", AboutSelf = "", FirstName = "Candidate1",LastName="Candidate1",Sex=SexType.Unspecified,Id= Guid.NewGuid().ToString() };
     UserManager.CreateAsync(user, "Candidate1");

...

【讨论】：