[英]Adding a background service that deletes data every 7 days
我有一個 class Issue
,其中包含一些信息,包括它們的日期。 我想創建一個后台服務,從數據庫中刪除超過 7 天的數據。
這是我試過的代碼:
using APIExample;
using Microsoft.Identity.Client;
public class BackgroundWorker : BackgroundService
{
private readonly AppDbContext _appDbContext;
public BackgroundWorker(AppDbContext appDbContext)
{
_appDbContext = appDbContext;
}
protected override Task ExecuteAsync(CancellationToken stoppingToken)
{
_appDbContext.Issue.RemoveRange(_appDbContext.Issue.Where(a => (a.Created.AddDays(7) >= DateTime.Now)));
_appDbContext.SaveChanges();
return Task.CompletedTask;
}
}
我已經在program.cs
中注入了這個 class
builder.Services.AddHostedService<BackgroundWorker>();
這是我得到的錯誤:
System.AggregateException:'無法構建某些服務(驗證服務描述符'ServiceType:Microsoft.Extensions.Hosting.IHostedService Lifetime:Singleton ImplementationType:BackgroundWorker'時出錯:無法使用來自singleton的范圍服務'APIExample.AppDbContext' Microsoft.Extensions.Hosting.IHostedService'.)'
你不能像這樣注入 DbContext,使用 ServiceScopeFactory
public class BackgroundWorker : BackgroundService
{
private readonly IServiceScopeFactory _serviceScopeFactory;
public BackgroundWorker(IServiceScopeFactory serviceScopeFactory)
{
_serviceScopeFactory = serviceScopeFactory;
}
protected override Task ExecuteAsync(CancellationToken stoppingToken)
{
using (var scope = _serviceScopeFactory.CreateScope())
{
var _appDbContext= scope.ServiceProvider.GetService<AppDbContext>();
_appDbContext.Issue.RemoveRange(_appDbContext.Issue.Where(a => (a.Created.AddDays(7) >= DateTime.Now)));
_appDbContext.SaveChanges();
return Task.CompletedTask;
}
}
}
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