尝试激活控制器时无法解析服务 DbContext

Question

我有自己的

DbContext

:

public class DreamsContext : DbContext
{
    public DbSet<UserAccount> UserAccounts { get; set; }
    public DbSet<DreamPublication> DreamPublications { get; set; }

    public DreamsContext(DbContextOptions<DreamsContext> options) : base(options)
    {
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<UserAccount>().ToTable("dreams_user");
        modelBuilder.Entity<DreamPublication>().ToTable("dream_publications");

        base.OnModelCreating(modelBuilder);
    }
}

其中

UserAccount

和

DreamPublication

仅包含几个带有 get 和 set 的字段。

在我的启动中，我为

DbContext

添加了这个：

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<Models.DreamsContext>(options =>
                options.UseSqlServer("server = SCAT\\SQLEXPRESS; database = dreams_web; Trusted_Connection=True ; MultipleActiveResultSets = true"));
}

然后我尝试使用 DI 将我的

DbContext

注入到控制器中：

private readonly Models.DreamsContext _context;

public SignUpController (Models.DreamsContext dbContext)
{
    _context = dbContext;
}

但是当我尝试在这种情况下做某事时，我遇到了一个例外：

尝试激活“（我的控制器）”时无法解析类型“（我的 DbContext）”的服务

我不知道该怎么办，在 MSDN 上他们就是这么做的，一切正常

更新。这是console中写的

System.InvalidOperationException: Unable to resolve service for type 'DreamWeb.Models.DreamsContext' while attempting to activate 'DreamWeb.Controllers.SignUpController'.
         at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetService(IServiceProvider sp, Type type, Type requiredBy, Boolean isDefaultParameterRequired)
         at lambda_method25(Closure , IServiceProvider , Object[] )
         at Microsoft.AspNetCore.Mvc.Controllers.ControllerActivatorProvider.<>c__DisplayClass7_0.<CreateActivator>b__0(ControllerContext controllerContext)
         at Microsoft.AspNetCore.Mvc.Controllers.ControllerFactoryProvider.<>c__DisplayClass6_0.<CreateControllerFactory>g__CreateController|0(ControllerContext controllerContext)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync()
      --- End of stack trace from previous location ---
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|25_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()
      --- End of stack trace from previous location ---
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
         at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
         at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
         at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

Answer 1

主要问题是我试图在 Startup 类中配置服务，而我正在使用 asp.net CORE，所以主要的魔力在于 program.cs 我将所有内容移至program.cs，一切正常。就这么点小错误也花了我好几天时间

https://learn.microsoft.com/en-us/dotnet/architecture/porting-existing-aspnet-apps/app-startup-differences

据此，启动应该继续在asp.net core中工作，但我遇到了问题

Answer 2

我遇到了同样的问题，通过在 Project Program.cs 的主文件中添加到数据库的连接来解决，将其添加到 var builder 行之后：

// db connection 
builder.Services.AddDbContext<Dbcontexclass>(options =>
    options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnectionString"));

在appsettings.json中添加：

 "ConnectionStrings": {
    "DefaultConnectionString": "SERVER=server;DATABASE=database;User ID=user;PASSWORD=password;"
  }

填写 Connection String 、 Dbcontexclass ，它应该可以工作，我给您留下文档链接（https://learn.microsoft.com/en-us/aspnet/core/tutorials/first-mvc-app/working-with -sql?view=aspnetcore-7.0&tabs=visual-studio )

Answer 3

在

appsettings.json

中添加以下内容解决了我的问题，谢谢！

  "ConnectionStrings": {
      "DefaultConnection": "Connection String Value"
    }