实体框架7异步集合

Question

实体框架7中的ToListAsync（）在哪里。如何在EF 7中使用异步方法返回集合或SingleOrDefault。

 public async Task<IEnumerable<TodoItem>> GetAllAsync()
    {   
        //TODO: ToListAsync missing?         

        return await _context.Todos.ToAsyncEnumerable();
    }

这是返回错误，不包含GetAwaiter的定义？ SaveChangesAsync没问题。

Answer 1

Microsoft.EntityFrameworkCore命名空间

Microsoft.EntityFrameworkCore命名空间包含async扩展方法。该命名空间位于Microsoft.EntityFrameworkCore包中。这是the source on GitHub，这是async扩展方法。

• AnyAsync()
• AllAsync()
• CountAsync()
• LongCountAsync()
• FirstAsync()
• FirstOrDefaultAsync()
• LastAsync()
• LastOrDefaultAsync()
• SingleAsync()
• SingleOrDefaultAsync()
• MinAsync()
• MaxAsync()
• SumAsync()
• AverageAsync()
• ContainsAsync()
• ToListAsync()
• ToArrayAsync()
• LoadAsync()
• ToDictionaryAsync()
• ForEachAsync()

使用示例

project.json

"Microsoft.EntityFrameworkCore": "1.0.0",

ApplicationUserRepository.cs

using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;

namespace MyApplication.Models {
    public class ApplicationUserRepository : IApplicationUserRepository
    {
        private ApplicationDbContext _dbContext;

        public ApplicationUserRepository(ApplicationDbContext dbContext) {
            _dbContext = dbContext;
        }

        public async Task<ApplicationUser> Find(Guid id)
        {
            return await _dbContext.Users.SingleAsync(u => u.Id == id);
        }

        public async Task<IEnumerable<ApplicationUser>> GetAll()
        {
            return await _dbContext.Users.ToListAsync();
        }
    }
}

Answer 2

ToListAsync()和SingleOrDefaultAsync()以及Microsoft.Data.Entity包中的名称空间EntityFramework.Core中存在许多其他异步方法。