我使用.net 5和React模板创建了一个ASP.NET Core Web App,并在VS向导中启用了身份验证。为dbContext创建的代码是这样的:
public class ApplicationDbContext : ApiAuthorizationDbContext<ApplicationUser>
{
public ApplicationDbContext(
DbContextOptions options,
IOptions<OperationalStoreOptions> operationalStoreOptions) : base(options, operationalStoreOptions)
{
}
我想以如下方式从Program.cs调用的seedData方法中访问此dbContext:
var host = CreateHostBuilder(args).Build();
using (var scope = host.Services.CreateScope())
{
var services = scope.ServiceProvider;
try { SeedData.Initialize(services); } ...
当我尝试在SeedData / Initialize中获取对我的上下文的引用时,由于以下实例化DbContextOptions时构造函数的第二个参数丢失,所以我得到了一个空引用错误(null显然是错误的,但是我不知道我在做什么应该通过)
public static class SeedData
{
public static void Initialize(IServiceProvider serviceProvider)
{
using ApplicationDbContext context = new ApplicationDbContext(
serviceProvider.GetRequiredService<
DbContextOptions<ApplicationDbContext>>(),null);
试试这个:
首先,您必须创建范围并从program.cs中获取需求服务(ApplicationUser继承自IdentityUser)。
public static void Main(string[] args)
{
var host = CreateHostBuilder(args).Build();
using (var scope = host.Services.CreateScope())
{
var services = scope.ServiceProvider;
var userManager = services.GetRequiredService<UserManager<ApplicationUser>>();
ApplicationDbContextSeed.SeedDefaultUserAsync(userManager)
.GetAwaiter().GetResult(;
}
host.Run();
}
接下来,您必须在播种类中创建静态播种方法,例如:
public class ApplicationDbContextSeed
{
public static async Task SeedDefaultUserAsync(UserManager<ApplicationUser> userManager)
{
var user = new ApplicationUser()
{
Email = "email",
UserName = "username",
};
await userManager.CreateAsync(user, "password");
}
}
您也可以在此课程中播种数据库
public static async Task SeedSampleDataAsync(ApplicationDbContext context)
{
// Seed, if necessary
if (!context.TodoLists.Any())
{
context.TodoLists.Add(new TodoList
{
Title = "Shopping",
Items =
{
new TodoItem { Title = "Apples", Done = true },
new TodoItem { Title = "Milk", Done = true },
new TodoItem { Title = "Bread", Done = true },
new TodoItem { Title = "Toilet paper" },
new TodoItem { Title = "Pasta" },
new TodoItem { Title = "Tissues" },
new TodoItem { Title = "Tuna" },
new TodoItem { Title = "Water" }
}
});
await context.SaveChangesAsync();
}
}
最后在program.cs中调用此方法
public static void Main(string[] args)
{
var host = CreateHostBuilder(args).Build();
using (var scope = host.Services.CreateScope())
{
var services = scope.ServiceProvider;
var userManager = services.GetRequiredService<UserManager<ApplicationUser>>();
ApplicationDbContextSeed.SeedDefaultUserAsync(userManager)
.GetAwaiter().GetResult(;
var context = services.GetRequiredService<ApplicationDbContext>();
await ApplicationDbContextSeed.SeedSampleDataAsync(context);
}
host.Run();
}
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