C# 无法解决此错误，"；没有为此DbContext配置数据库提供程序；

经过长时间的休息后，我最近回到了ASP.Net，并一直在尝试使用Core2.1开发web应用程序

我遵循了Microsoft网站上的一个“开始”指南，我与SQLExpress连接字符串的数据提供程序有问题

当我尝试访问SQLExpress时，不断出现错误“没有为此DbContext配置数据库提供程序”

完全错误

An unhandled exception occurred while processing the request.
InvalidOperationException: No database provider has been configured for this DbContext. A provider can be configured by overriding the DbContext.OnConfiguring method or by using AddDbContext on the application service provider. If AddDbContext is used, then also ensure that your DbContext type accepts a DbContextOptions<TContext> object in its constructor and passes it to the base constructor for DbContext.
Microsoft.EntityFrameworkCore.Internal.DbContextServices.Initialize(IServiceProvider scopedProvider, IDbContextOptions contextOptions, DbContext context)

Stack Query Cookies Headers
InvalidOperationException: No database provider has been configured for this DbContext. A provider can be configured by overriding the DbContext.OnConfiguring method or by using AddDbContext on the application service provider. If AddDbContext is used, then also ensure that your DbContext type accepts a DbContextOptions<TContext> object in its constructor and passes it to the base constructor for DbContext.
Microsoft.EntityFrameworkCore.Internal.DbContextServices.Initialize(IServiceProvider scopedProvider, IDbContextOptions contextOptions, DbContext context)
Microsoft.EntityFrameworkCore.DbContext.get_InternalServiceProvider()
Microsoft.EntityFrameworkCore.DbContext.get_DbContextDependencies()
Microsoft.EntityFrameworkCore.DbContext.get_Model()
Microsoft.EntityFrameworkCore.Internal.InternalDbSet<TEntity>.get_EntityType()
Microsoft.EntityFrameworkCore.Internal.InternalDbSet<TEntity>.get_EntityQueryable()
Microsoft.EntityFrameworkCore.Internal.InternalDbSet<TEntity>.System.Linq.IQueryable.get_Provider()
Microsoft.EntityFrameworkCore.RelationalQueryableExtensions.FromSql<TEntity>(IQueryable<TEntity> source, RawSqlString sql, object[] parameters)
SQL_Connection_2.Pages.ContactModel.OnGet() in Contact.cshtml.cs
Microsoft.AspNetCore.Mvc.RazorPages.Internal.ExecutorFactory+VoidHandlerMethod.Execute(object receiver, object[] arguments)
Microsoft.AspNetCore.Mvc.RazorPages.Internal.PageActionInvoker.InvokeHandlerMethodAsync()
Microsoft.AspNetCore.Mvc.RazorPages.Internal.PageActionInvoker.InvokeNextPageFilterAsync()
Microsoft.AspNetCore.Mvc.RazorPages.Internal.PageActionInvoker.Rethrow(PageHandlerExecutedContext context)
Microsoft.AspNetCore.Mvc.RazorPages.Internal.PageActionInvoker.Next(ref State next, ref Scope scope, ref object state, ref bool isCompleted)
Microsoft.AspNetCore.Mvc.RazorPages.Internal.PageActionInvoker.InvokeInnerFilterAsync()
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResourceFilter()
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(ref State next, ref Scope scope, ref object state, ref bool isCompleted)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeFilterPipelineAsync()
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeAsync()
Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)
Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

ConfigurationContext.cs

公共类配置上下文：DbContext{
公共配置上下文（）{}
公共配置上下文（DbContextOptions选项）：基本（选项）{}
公共DbSet Persons{get；set；}
}

如果我将

ConfigurationContext.cs

中的代码更改为（以下），一切都可以正常工作，但这绕过了

appsettings.json

中的连接字符串，因此看起来好像

services.AddDbContext

在

Startup.cs

文件中执行

公共类配置上下文：DbContext{
配置时受保护的覆盖无效（DBContextOptions Builder Options Builder）{
optionsBuilder.UseSqlServer（@“服务器=。\SQLExpress；数据库=WebApp\u测试；受信任的\u连接=真；MultipleActiveResultSets=真；”）；
}
}

有人能就如何修复此问题提供建议吗？理想情况下，我希望在

appsettings.json

文件中配置连接字符串

---

我花了很多时间试图解决这个问题，寻找发现和学习的时刻。

尝试使用您在onconfigurang方法中使用的连接字符串，因为您发布的内容不同

像这样-

  "ConnectionStrings": {
    "MyConnection": "Server=.\SQLExpress;Database=WebApp_Test;Trusted_Connection=True;MultipleActiveResultSets=true;"
  }

---

Startup.cs，添加ConnectionService.Set

public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
        ConnectionService.Set(configuration);
    }

ConnectionService.cs

public static string connstring = "";
public static string Set(IConfiguration config)
    {
        connstring = config.GetConnectionString("MyConnection");
    }

ConfigurationContext.cs

public class ConfigurationContext : DbContext {

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) {
        optionsBuilder.UseSqlServer(ConnectionService.connstring);
    }

}

---

太好了，成功了，谢谢！我确实需要做一个小小的调整<代码>公共静态无效集（IConfiguration config）我的荣幸。只要一切正常，你可以随意调整。：）我非常不喜欢这种解决办法。为什么要创建一些虚拟服务来只保存这个连接字符串，而EF配置清楚地说明您应该能够将选项传递给dbcontexts构造函数？这段代码太脏了…你把答案贴出来吧。他想将connectionstring从appsettings.json传递到Dbcontext，而Startup.cs中的AddDbContext无法获得它。没有别的了。