初学ASP.NET CORE,按照文档练习,在使用SQL的时候代码出现如下错误
System.InvalidOperationException
HResult=0x80131509
Message=Cannot resolve scoped service 'Microsoft.EntityFrameworkCore.DbContextOptions`1[WebApplication2.Models.WebApplication2Context]' from root provider.
Source=Microsoft.Extensions.DependencyInjection
StackTrace:
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteValidator.ValidateResolution(Type serviceType, IServiceScope scope, IServiceScope rootScope)
at Microsoft.Extensions.DependencyInjection.ServiceProvider.Microsoft.Extensions.DependencyInjection.ServiceLookup.IServiceProviderEngineCallback.OnResolve(Type serviceType, IServiceScope scope)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService(Type serviceType, ServiceProviderEngineScope serviceProviderEngineScope)
at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService(Type serviceType)
at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Type serviceType)
at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)
at WebApplication2.Models.SeedData.Initialize(IServiceProvider serviceProvider) in C:\Users\guosiqi\source\repos\WebApplication2\WebApplication2\Models\SeedData.cs:line 18
at WebApplication2.Startup.Configure(IApplicationBuilder app, IHostingEnvironment env) in C:\Users\guosiqi\source\repos\WebApplication2\WebApplication2\Startup.cs:line 71
这是因为注册的WebApplication2Context用的是Scope,但是在Scope外访问WebApplication2Context,所以抛出了异常
在这个方法中单独创建一个Scope
public class SeedData
{
public static void Initialize(IServiceProvider serviceProvider)
{
//注册的WebApplication2Context用的是Scope,但是在Scope外访问WebApplication2Context,所以抛出了异常
//在这个方法中单独创建一个Scope
using (var serviceScope = serviceProvider.CreateScope()) //手动高亮
{
using (var context = new WebApplication2Context(
//这里要使用serviceScope.ServiceProvider
serviceScope.ServiceProvider.GetRequiredService<DbContextOptions<WebApplication2Context>>()))
{
// Look for any movies.
}
}
}
}
问题解决