Question

我的关系像客户一样分层 - ＆gt;地址 - ＆gt;接触

单个客户可能有多个地址，而单个地址可能有多个联系人。看我的班级结构。

   public class CustomerBase
    {
        public int CustomerID { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
    }

    public class Customer : CustomerBase
    {
        public virtual List<Addresses> Addresses { get; set; }
    }

    public class Addresses
    {
        [Key]
        public int AddressID { get; set; }
        public string Address1 { get; set; }
        public string Address2 { get; set; }
        public bool IsDefault { get; set; }
        public virtual List<Contacts> Contacts { get; set; }

        public int CustomerID { get; set; }
        public virtual Customer Customer { get; set; } 

    }

    public class Contacts
    {
        [Key]
        public int ContactID { get; set; }

        public string Phone { get; set; }
        public string Fax { get; set; }

        public int AddressID { get; set; }
        public virtual Addresses Customer { get; set; } 

    }

    public class TestDBContext : DbContext
    {
        public TestDBContext()
            : base("name=TestDBContext")
        {
        }

        public DbSet<Customer> Customer { get; set; }
        public DbSet<Addresses> Addresses { get; set; }
        public DbSet<Contacts> Contacts { get; set; }
    }

这样我就是db表中的人口数据，首先是EF代码。

    using (var db = new TestDBContext())
    {
        var customer = new Customer
        {
            FirstName = "Test Customer2",
            LastName = "Test Customer2",
            Addresses = new List<Addresses>
            {
                new Addresses
                {
                    Address1 = "foo1",
                    Address2 = "foo2",
                    IsDefault=true,
                    Contacts =  new List<Contacts>
                    {
                       new Contacts {  Phone = "22222222", Fax = "1-999999999" }
                    }
                }
            }
        };

        db.Customer.Add(customer);
        db.SaveChanges();

现在我想查询数据。假设我想要获取customerid is 1并希望加载与客户ID相关的地址为1并且地址Isdefault为真且默认地址相关的联系人详细信息的客户。

我尝试以这种方式撰写它因此无法完成，因为我在EF和LINQ查询。

var bsCustomer = db.Customer.Where(c => c.CustomerID == 2).Include(a=> 
a.Addresses.Where(a=> a.IsDefault==true)).Include(c=> c.)

所以请告诉我什么是查询，结果客户ID 1相关地址将加载其isdefault将为true并且将加载与地址相关的联系人。感谢

Answer 1

您可以尝试如下所示。

基于查询的语法：

var dbquery =  from cu in db.Customers 
               where (cu.CustomerID  == 1) 
               select new { 
                           cu,  
                           Addresses= from ad in cu.Addresses
                                      where (ad.IsDefault == true) 
                                      from ct in ad.Contacts  
                                      select ad,

             };

您可以根据需要进行迭代：

var customers = dbquery.AsEnumerable() 
                       .Select(c => c.cu);

foreach(var customer in customers ) 
{ 
    foreach(var address in customer.Addresses) 
     {
       //your code; 
     }
}

基于方法的语法：

var dbquery =  db.Customers.Where(cu=>cu.CustomerID  == 1) 
               .Select(cus=> new { 
                   cus,  
                   Addresses= cus.Addresses.Where(ad=>ad.IsDefault == true).Include(c=>c.Contacts)
                   }).AsEnumerable()
                   .Select(f => f.cus).ToList();

使用实体框架

这样我就是db表中的人口数据，首先是EF代码。

1 个答案: