Question

这些是我的课程：

public class Restaurant
{
    [Key]
    public int Id { get; set; }
    public string Name { get; set; }
    public City City { get; set; }
    public List<Meal> Meals { get; set; }
}

public class Meal
{
    [Key]
    public int Id { get; set; }
    public string Name { get; set; }
    public DateTime Date { get; set; }
    public int Price { get; set; }
    public int Number { get; set; }
    public int Kind { get; set; }
}

现在我想创建一个查询，它给出了我在城市中的餐馆列表以及今天的日期，所以我开始这样：

return db.Restaurants.Where(rest => rest.City.Name == city).Include(rest => rest.Meals);

但我不确定如何与这部分联系：

.Where(meal => meal.Date == DateTime.Today)

所以我会得到我想要的结果。那怎么可能做到这一点？感谢

修改

我的结果：

        return db.Restaurants
                 .Include(rest => rest.Meals)
                 .Where(rest => rest.City.Name == city)
                 .AsEnumerable()
                 .Select(r => new Restaurant()
                     {
                         City = r.City,
                         Id = r.Id,
                         Name = r.Name,
                         Meals = r.Meals.Where(meal => meal.Date == DateTime.Today).ToList()
                     });

Answer 1

这应该在View Model（或Dto）图层中完成，首先，定义您的视图模型：

public class RestaurantVM
{
    public int Id { get; set; }
    public string Name { get; set; }
    public City City { get; set; }
    public List<MealVM> Meals { get; set; }
}

public class MealVM
{
    public int Id { get; set; }
    public string Name { get; set; }
    public DateTime Date { get; set; }
    public int Price { get; set; }
    public int Number { get; set; }
    public int Kind { get; set; }
}

然后你可以写下面的LINQ：

var restaurantVMs = db.Restaurants
                  .Include(rest => rest.Meals)
                  .Where(rest => rest.City.Name == city)
                  .AsEnumerable()
                  .Select(r => new RestaurantVM(){
                        Id = r.Id,
                        Name = r.Name,
                        City = r.City,
                        Meals = r.Meals.Where(meal => meal.Date == DateTime.Today)
                                       .Select(m => new MealVM(){
                                            ...
                                        }).ToList()
                    }).Where(r => r.Meals.Count > 0);

Linq查询以获取筛选的主集合以及该集合中的每个结果列表

1 个答案: