Question

我有两个类，形成多对多的关系。

public class Product
{
    public int ID { get; set; }
    public virtual ICollection<Category> Categories{ get; set; }
}

public class Category
{
    public int ID { get; set; }
    public virtual ICollection<Product> Products{ get; set; }
}

我需要选择某些类别中包含的所有产品。例如，ID等于1的所有类别的产品，或ID为1和3的类别中的所有产品。如何在Linq中编写此查询？

注意：我想用它作为过滤技术。我有这段代码：

public IQueryable<Product> GVProducts_GetData(string Sort)
        {
            var query = _db.Products.AsQueryable();

            //Here I want filter my data 
            if (Sort == "1")
            {
                query = (here should select all the product which are in category 1)
            }
            else if (Sort == "2")
            {
                query = (here should select all the product which are in category 2)
            }
        return query;

}

Answer 1

     DbContext.Category.Where(c => c.ID == 1)
      .Include(c => c.Products).Select(x => x.Products).ToList();

可能是这样的。请务必使用Include。

Answer 2

创建方法：

  public IEnumerable<Product> GetProducts(params int[] selectCategory )
   {               
     return repository.Query<Category>       
    (p => selectCategory.Contains(p.ID)).SelectMany(p => p.Products).ToList()

   }

使用示例：

var product = GetProducts(1,3,5);

其中1,3,5寻求类别

EF Code First Linq查询多对多

2 个答案: