实体框架支架和迁移不起作用

Question

我在asp.net webapi项目中使用一个具有1个代码优先DbContext和1个数据库优先DbContext的项目。运行以下命令更新db/context会导致以下错误:

---

dotnet ef dbcontext scaffold Name=ConnectionStrings:Cloud Microsoft.EntityFrameworkCore.SqlServer

System.InvalidOperationException: A named connection string was used, but the name 'ConnectionStrings:Cloud' was not found in the application's configuration. Note that named connection strings are only supported when using 'IConfiguration' and a service provider, such as in a typical ASP.NET Core application. See
https://go.microsoft.com/fwlink/?linkid=850912 for more information.
at Microsoft.EntityFrameworkCore.Storage.Internal.NamedConnectionStringResolverBase.ResolveConnectionString(String connectionString)
at Microsoft.EntityFrameworkCore.Scaffolding.Internal.ReverseEngineerScaffolder.ScaffoldModel(String connectionString, DatabaseModelFactoryOptions databaseOptions, ModelReverseEngineerOptions modelOptions, ModelCodeGenerationOptions codeOptions)
at Microsoft.EntityFrameworkCore.Design.Internal.DatabaseOperations.ScaffoldContext(String provider, String connectionString, String outputDir, String outputContextDir, String dbContextClassName, IEnumerable`1 schemas, IEnumerable`1 tables, String modelNamespace, String contextNamespace, Boolean useDataAnnotati
ons, Boolean overwriteFiles, Boolean useDatabaseNames, Boolean suppressOnConfiguring, Boolean noPluralize)
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.ScaffoldContextImpl(String provider, String connectionString, String outputDir, String outputDbContextDir, String dbContextClassName, IEnumerable`1 schemaFilters, IEnumerable`1 tableFilters, String modelNamespace, String contextNamespace, Boolean useData
Annotations, Boolean overwriteFiles, Boolean useDatabaseNames, Boolean suppressOnConfiguring, Boolean noPluarlize)
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.ScaffoldContext.<>c__DisplayClass0_0.<.ctor>b__0()
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0()
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)

---

dotnet迁移添加测试-c AdminContext

System.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.
at Microsoft.EntityFrameworkCore.Internal.DbContextServices.Initialize(IServiceProvider scopedProvider, IDbContextOptions contextOptions, DbContext context)
at Microsoft.EntityFrameworkCore.DbContext.get_InternalServiceProvider()
at Microsoft.EntityFrameworkCore.DbContext.Microsoft.EntityFrameworkCore.Infrastructure.IInfrastructure<System.IServiceProvider>.get_Instance()
at Microsoft.EntityFrameworkCore.Infrastructure.Internal.InfrastructureExtensions.GetService[TService](IInfrastructure`1 accessor)
at Microsoft.EntityFrameworkCore.Infrastructure.AccessorExtensions.GetService[TService](IInfrastructure`1 accessor)
at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(Func`1 factory)
at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(String contextType)
at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.AddMigration(String name, String outputDir, String contextType, String namespace)
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType, String namespace)
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigration.<>c__DisplayClass0_0.<.ctor>b__0()
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0()
at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)

---

这是我的代码

public static class Program {
public static void Main(string[] args) {
Host.CreateDefaultBuilder(args).ConfigureWebHostDefaults(webBuilder => { webBuilder.UseStartup<Startup>(); }).Build().Run();
}
}

public class Startup {
public Startup(IConfiguration configuration) {
Configuration = configuration;
}
private IConfiguration Configuration { get; }
// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services) {
services.AddDbContext<AdminContext>(options => options.UseSqlServer(Configuration.GetConnectionString("Admin")));
services.AddDbContext<CloudContext>(options => options.UseSqlServer(Configuration.GetConnectionString("Cloud")));
services.AddControllers();
}
public void Configure(IApplicationBuilder app, IWebHostEnvironment env) {
app.UseHsts();
app.UseHttpsRedirection();
app.UseRouting();
app.UseAuthorization();
app.UseEndpoints(endpoints => { endpoints.MapControllers(); });
}
}

public class AdminContext : DbContext {
public AdminContext() { }
public AdminContext(DbContextOptions<AdminContext> options) : base(options) { }

public DbSet<User> Users { get; set; }
}

我真的在做异常想让我做的事吗?有人能告诉我如何解决这个问题吗?
应用程序本身运行良好，并正确地使用了appsettings/user-secrets和连接字符串。
我使用的是。net 5.0.402和ef 5.0.11

Answer 1

我猜你的配置(appsettings.json/usersecrets)是畸形的，应该是这样的:

{
"ConnectionStrings": {
"Admin": "***",
"Cloud": "***"
},
...
}

也尝试从上下文中删除空构造函数(可能会导致使用而不是DbContextOptions)

Answer 2

change my Program.cs to

public static class Program {
public static void Main(string[] args) => CreateHostBuilder(args).Build().Run();
// EF Core uses this method at design time to access the DbContext
public static IHostBuilder CreateHostBuilder(string[] args) =>
Host.CreateDefaultBuilder(args).ConfigureWebHostDefaults(webBuilder => webBuilder.UseStartup<Startup>());
}

修复了