nhibernate - Nhibernate联接另一个表

我需要对客户进行加入。地址为主要地址，并填充PrimaryAddress1和PrimaryCity字段。客户映射已经与地址类具有很多关系，但是我不想获取所有地址（性能问题）。

请帮忙..

类：

public class Customer
{
    public Customer()
    {
        Addressess = new List<Address>();
    }
   public virtual int CustomerID { get; set; }
    public virtual int? BranchID { get; set; }
    public virtual int? CustTypeID { get; set; }
    public virtual string CompanyName { get; set; }
    public virtual string Prefix { get; set; }
    public virtual string FirstName { get; set; }
    public virtual string MiddleName { get; set; }
    public virtual string LastName { get; set; }
    public virtual string PrimaryAddress1 { get; set; }
    public virtual string PrimaryCity { get; set; }
    public virtual List<Address> Addresses { get; set; }
}


public class Address
{
    public Address()
    {
    }
    public virtual int LocationID { get; set; }
    public virtual int? CustomerID { get; set; }
    public virtual string LocationName { get; set; }
    public virtual string Address1 { get; set; }
    public virtual string Address2 { get; set; }
    public virtual string Address3 { get; set; }
    public virtual string City { get; set; }
    public virtual bool Primary { get; set; }
}

对应：

public TblCustomerMap()
{
    Table("tblCustomers");
    LazyLoad();
    Id(x => x.CustomerID).GeneratedBy.Identity().Column("CustomerID");
    Map(x => x.ProfileID).Column("ProfileID");
    Map(x => x.BranchID).Column("BranchID");
    Map(x => x.DateEntered).Column("DateEntered");
    Map(x => x.DateTerminated).Column("DateTerminated");
    Map(x => x.CustTypeID).Column("CustTypeID");
    Map(x => x.CompanyName).Column("CompanyName").Not.Nullable().Length(50);
    Map(x => x.Prefix).Column("Prefix").Not.Nullable().Length(50);
    Map(x => x.FirstName).Column("FirstName").Not.Nullable().Length(50);
    Map(x => x.MiddleName).Column("MiddleName").Not.Nullable().Length(50);
    Map(x => x.LastName).Column("LastName").Not.Nullable().Length(50);
    HasMany(x => x.Address).KeyColumn("CustomerID");
    Map(x => x.PrimaryAddress1).Column("PrimaryAddress1") // from table tbladdress where address is primary and get data from address1 column
    Map(x => x.PrimaryCity).Column("PrimaryCity") // from table tbladdress where address is primary and get data from city column
}

查询：

 var query = session
            .QueryOver<Customer>(() => customer)
            .JoinQueryOver(() => customer.Addresses, () => address)
            .Where(() => address.Primary)
            .List();

        foreach (var customer1 in query)
        {
            customer1.PrimaryAddress1 = customer1.Addresses[0].Address1;
            customer1.PrimaryCity = customer1.Addresses[0].City;
            customer1.PrimaryState = customer1.Addresses[0].StateOrProvince;

        }

新查询：

  var query = session.Query<Customer>()
            .SelectMany(c => c.Addresses,
                        (c, a) => new {c, a})
            .Where(cust => cust.a.Primary)
            .Select(item => new CustomerView()
                              {
                                 CustomerID = item.c.CustomerID,
                                 CompanyName=  item.c.CompanyName,
                                 FirstName=  item.c.FirstName,
                                  LastName=item.c.LastName,
                                  Address1=item.a.Address1,
                                  Address2=item.a.Address2,
                                 Address3= item.a.Address3,
                                 City= item.a.City,
                                 StateOrProvince= item.a.StateOrProvince
                              });
        return query.ToList();

最佳答案

有（至少）两种方法可以实现此目的。

1）扩展DB和调整NHibernate映射更加直观和可读。我们将需要创建新的视图viewPrimaryAddress。

SELECT ***columns*** FROM [tbladdress] WHERE Primary = true

客户映射将如下所示：

Join("[viewPrimaryAddress]",
{
  m.Fetch.Join();
  m.KeyColumn("CustomerID");
  m.Map(t => t.PrimaryAddress1).Column("PrimaryAddress1");
  m.Map(t => t.PrimaryCity).Column("PrimaryCity");
});

就是这样。将发出一条SQL语句，因此无需加载Address集合

2）第二种方法的概述

第二种方法将通过新的类映射来创建该视图，这有点复杂，但是只能在应用程序端完成（C＃和NHiberante）。

将创建新的类PrimaryAddress，并在类级别定义中包含ilter（xml映射示例：

<class name="PrimaryAddress" ... where="Primary = true" >

然后，我们可以使用与Customer的新的多对一关系扩展PrimaryAddress。因此，将通过在WHERE子句中过滤的SQL select获得“ PrimaryAddress1”和“ PrimaryCity”列的属性。

扩展：

后续步骤应指导您如何创建新映射，并将主地址定位为一对一属性
1）C＃PrimaryAddress：

public class PrimaryAddress
{
    public virtual Customer Customer { get; set; }
    public virtual string Address { get; set; }
    public virtual string City { get; set; }
}

2）对应：

public TblPrimaryAddressMap()
{
    Table("tbladdress");
    LazyLoad();
    Where("Primary = 1");
    // Id as AddressId
    References(x => x.Customer).Column("CustomerID");
    Map(x => x.Address).Column("PrimaryAddress1")
    Map(x => x.PrimaryCity).Column("PrimaryCity")
}

3）Customer的新属性

public class Customer
{
   ..
   public virtual PrimaryAddress PrimaryAddress { get; set; }

4）Customer的新映射
公共TblCustomerMap（）
{
...
HasOne（x => x.PrimaryAddress）

此时，当您从会话获取Customer时。您可以访问

customer.PrimaryAddress.Address
customer.PrimaryAddress.City

我主要使用XML映射。但是从这些方面来看，这个概念应该很清楚...使用某些fetch="join"，您可以在一个SQL select中加载Customer及其PrimaryAddress

如果您甚至需要客户属性Customer.PrimaryAddress1，只需将PrimaryAddress.Address包装在getter中。

您将获得的更多收益是，可以通过此新属性PrimaryAddress进行过滤和排序

注意：这种方法对于缓存是脆弱的。原因是，您将更改实际的Address实体时，没有建立用于撤消PrimaryAddress的机制。而且，您还应强制业务定位器仅允许将一个地址设置为primary = true的客户

primaryAddress

nhibernate - Nhibernate联接另一个表