Question

我正在尝试使用Cosmos DB for Database创建基于.Net Core 3和EF Core 3的应用程序。

我已经按照以下步骤操作了，

public void ConfigureServices(IServiceCollection services)
{
 services.AddDbContext<MyDbContext>();
}

public class MyDbContextFactory : IDesignTimeDbContextFactory<MyDbContextFactory >
    {

        public MyDbContextFactory CreateDbContext(string[] args)
        {

            // Get environment
            string environment = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT");

            // Build config
            var config = new ConfigurationBuilder()
                .SetBasePath(Path.Combine(Directory.GetCurrentDirectory()))
                .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
                .AddJsonFile($"appsettings.{environment}.json", optional: true)
                .AddEnvironmentVariables()
                .Build();

            var cosmosDbOptions = config.GetSection("CosmosDb").Get<CosmosDbOptions>();
            var (cosmosDbEndpoint, cosmosDbKey, databaseName, collectionData) = cosmosDbOptions;
            var collectionNames = collectionData.Select(c => c.Name).ToList();

            var optionsBuilder = new DbContextOptionsBuilder<MyDbContextFactory>();
            optionsBuilder.UseCosmos(cosmosDbEndpoint, cosmosDbKey, databaseName);

            return new ActivityLoggerContext(optionsBuilder.Options);
        }

和

public class MyDbContextFactory : DbContext
    {
        public MyDbContextFactory (DbContextOptions<MyDbContextFactory > dbContextOptions) : base(dbContextOptions)
        {
        }

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

    }

当我执行命令时，

> dotnet ef database update

我收到以下错误。任何帮助或指针将不胜感激

System.InvalidOperationException：无法解析“ Microsoft.EntityFrameworkCore.Migrations.IMigrator”类型的服务。这通常是因为尚未为此DbContext配置任何数据库提供程序。可以通过重写DbContext.OnConfiguring方法或在应用程序服务提供程序上使用AddDbContext来配置提供程序。如果使用AddDbContext，则还应确保DbContext类型在其构造函数中接受DbContextOptions对象，并将其传递给DbContext的基本构造函数。在Microsoft.EntityFrameworkCore.Infrastructure.Internal.InfrastructureExtensions.GetService [TService]（IInfrastructure 1 accessor) at Microsoft.EntityFrameworkCore.Infrastructure.AccessorExtensions.GetService[TService](IInfrastructure 1访问器）处在Microsoft.EntityFrameworkCore.Design.DesignTimeServiceCollectionExtensions。<> c__DisplayClass1_0.b__7（IServiceProvider _）在Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitFactory（FactoryCallSite factoryCallSite，RuntimeResolverContext上下文）在Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor 2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument) at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitDisposeCache(ServiceCallSite transientCallSite, RuntimeResolverContext context) at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor 2.VisitCallSite（ServiceCallSite callSite，TArgument参数）处在Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve（ServiceCallSite callSite，ServiceProviderEngineScope范围）在Microsoft.Extensions.DependencyInjection.ServiceLookup.DynamicServiceProviderEngine。<> c__DisplayClass1_0.b__0（ServiceProviderEngineScope范围）在Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService（类型serviceType，ServiceProviderEngineScope serviceProviderEngineScope）在Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService（Type serviceType）在Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService（类型serviceType）在Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetService [T]（IServiceProvider提供程序）在Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.EnsureServices（IServiceProvider服务）在Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.UpdateDatabase（String targetMigration，String contextType）在Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabaseImpl（String targetMigration，String contextType）在Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabase。<> c__DisplayClass0_0。<。ctor> b__0（）在Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute（Action操作）无法解析类型为“ Microsoft.EntityFrameworkCore.Migrations.IMigrator”的服务。这通常是因为尚未为此DbContext配置任何数据库提供程序。可以通过重写DbContext.OnConfiguring方法或在应用程序服务提供程序上使用AddDbContext来配置提供程序。如果使用AddDbContext，则还要确保您的DbContext类型在其构造函数中接受DbContextOptions对象，并将其传递给DbContext的基本构造函数。

Answer 1

基于异常消息，您需要在添加dbcontext服务时或在dbcontext的OnConfiguring方法中配置数据库提供程序。

通过参考以下教程，我获得了成功：Using DbContext with dependency injection

在该教程中，它使用SqlLite，您可以通过添加Microsoft.EntityFrameworkCore.Cosmos

更改为使用consmos db。

带有Cosmos DB问题的DotNet Core 3 EF 3

1 个答案: