我的 ef 核心有问题。我有两个从数据库读取数据的服务。在一个页面上调用第一个服务,在第二个页面上调用第二个服务。当我单击按钮创建新程序时,出现错误。我通常从带有注入服务的页面调用它。有人可以帮我吗?
在应用程序中显示 https://i.stack.imgur.com/9NOmg.png
builder.Services.AddDbContextPool<Context>(options =>
{
options.UseSqlServer(builder.Configuration.GetConnectionString("Connection"));
});
测试服务1:
public class TestService1 : ITestService1
{
private readonly Context _context;
private readonly IMapper _mapper;
public TestService1(Context context, IMapper mapper)
{
_kreativgangContext = kreativgangContext;
_mapper = mapper;
}
public virtual async Task<AllProgramViewModel> HandleAsync(AllProgramFilterViewModel filter)
{
var model = new AllProgramViewModel();
var data = _context.Programs.Where(x => (EF.Functions.Like(x.Name ?? "", "%" + filter.Name + "%") || string.IsNullOrEmpty(filter.Name)))
.Select(x => new Core.Models.Program() { ID = x.ID, Name = x.Name, Order = x.Order });
result.Model.TotalCount = await data.CountAsync();
result.Model.Items = data.Select(x => _mapper.Map<AllProgramItemViewModel>(x));
return model;
}
}
public interface ITestService1
{
public Task<AllProgramViewModel> HandleAsync(AllProgramFilterViewModel filter);
}
测试服务2:
public class TestService2 : ITestService2
{
private readonly Context _context;
public TestService2(Context context)
{
_context = context;
}
public virtual async Task<NewProgramViewModel> HandleAsync()
{
var model = new NewProgramViewModel();
List<ProgramOrderViewModel> items = _context.Programs.Select(x => new Core.Models.Program() { Order = x.Order, ID = x.ID })
.Select(x => new ProgramOrderViewModel()
{
ID = x.ID,
Order = x.Order
}).ToList();
return await Task.FromResult(model);
}
}
public interface ITestService2
{
public Task<NewProgramViewModel> HandleAsync();
}
Error:
Error: System.InvalidOperationException: A second operation was started on this context instance before a previous operation completed. This is usually caused by different threads concurrently using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.
at Microsoft.EntityFrameworkCore.Infrastructure.Internal.ConcurrencyDetector.EnterCriticalSection()
at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.Enumerator.MoveNext()
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
at Mitar.Kreativgang.Admin.Handlers.TestService2.HandleAsync() in D:\Programming\Kreativgang\Src\Mitar.Kreativgang.Admin\Handlers\TestService2.cs:line 26
at Mitar.Kreativgang.Admin.Pages.Program.ProgramNew.OnInitializedAsync() in D:\Programming\Kreativgang\Src\Mitar.Kreativgang.Admin\Pages\Program\ProgramNew.razor:line 114
at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()