如何在控制台应用程序 C# 中使用异步等待

Question

This is the method inside the repository:

public async Task<IEnumerable<T>> FindAll()
    {
        IQueryable<T> query = this.Context.Set<T>();
        return await query.Select(e => e).ToListAsync();
    }


public class Program
{
    static void Main(string[] args)
    {
        DB dB = new DB();
        IUnitOfWork unitOfWork = new UnitOfWork(dB);
        Task<IEnumerable<User>> users = unitOfWork.UserRepository.FindAll();
        users.Wait();
        Console.WriteLine(users);
    }
}

When I run my code I am getting:

System.Runtime.CompilerServices.AsyncTaskMethodBuilder'1+AsyncStateMachineBox'1[System.Collections.Generic.IEnumerable'1[PasteBook.WebApi.Models.User],PasteBook.WebApi.Repositories.GenericRepository'1+d__5[PasteBook.WebApi.Models.User]]

Answer 1

The simplest option is just to use an async entry point:

public class Program
{
    // async Main method, with a Task return type
    static async Task Main(string[] args)
    {
        DB dB = new DB();
        IUnitOfWork unitOfWork = new UnitOfWork(dB);
        // It's fine to await within the async method
        var users = await unitOfWork.UserRepository.FindAll();
        foreach (var user in users)
        {
            Console.WriteLine(user);
        }
    }
}

(Note that this answer doesn't try to address whether you should be using this particular database access pattern - it's focused on "how to use await from a console app.)