在继承自IHostedService的类中使用Entity Framework Core db上下文时缺少方法

Question

I have set up the example project inside the .NET Core repo for background tasks and I want to play with the real database records for something I need. But that seems impossible because the context methods only show those of Create Update Delete operations. To be more specific, I cannot find a Where , FirstOrDefault , First , .... As in, I can't use the "Read" operations. Has anyone encountered this? Am I doing something wrong?

The problem occurs on .NET Core version 2.2. My DbContext inherits from Microsoft.EntityframeworkCore.DbContext .

My DbContext :

public class APIContext:DbContext
{
    public static string ConnectionString { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseMySql(ConnectionString);
    }

    public DbSet<User> Users { get; set; }
    public DbSet<Userinfo> Userinfos { get; set; }
    public DbSet<Info> Infos { get; set; }
    public DbSet<Picture> Pictures { get; set; }
    public DbSet<Video> Videos { get; set; }
    public DbSet<Feed> Feeds { get; set; }
    public DbSet<Watchlist> Watchlists { get; set; }
    public DbSet<Sale> Sales { get; set; }
    public DbSet<CouponCode> CouponCodes { get; set; }
    public DbSet<CouponUser> CouponUsers { get; set; }
    public DbSet<Order> Orders { get; set; }
}

Hosted service:

internal class TimedHostedService : IHostedService, IDisposable
{
    private readonly ILogger _logger;
    private readonly APIContext context;
    private Timer _timer;

    public TimedHostedService(ILogger<TimedHostedService> logger, APIContext context)
    {
        _logger = logger;
        this.context = context;
    }
    ...

    private void DoWork(object state) //this is called by the start method of the service within this class
    {
        context.Users. //this is where I don't get the other methods of DbContext
        _logger.LogInformation("Timed Background Service is working.");
    }

Answer 1

You should use IQueryable from System.Ling to work with those methods. Here EntityFramework Core reference: