NHibernate 选择特定列

Question

public class Company_Product
{
    public virtual Int32 Id { get; set; }
    public virtual DateTime SalesDate { get; set; }
    public virtual Company Company{ get; set; }
    public virtual Product Product { get; set; }
}

public class Company
{
    public virtual Int32 Id { get; set; }
    public virtual string Name { get; set; }
    public virtual IList<Company_Product> company_product { get; set; }
}

public class Product
{
    public virtual Int32 Id { get; set; }
    public virtual string Name { get; set; }
    public virtual IList<Company_Product> company_product { get; set; }
}

公司.hbm.xml

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
                   assembly="BusinessObjectApp"
                   namespace="BusinessObjectApp.Modal">

    <!-- more mapping info here -->
    <class name="Company" table="[Company]">
        <id name="Id" column="Id">
            <generator class="native" />
        </id>
        <property name="Name" column="Name" />

        <bag name="company_product" table="[Company_Product]" inverse="true" lazy="true">
            <key column="CompanyID" />
            <one-to-many class="Company_Product" />
        </bag>
    </class>
</hibernate-mapping>

Company_Product.hbm.xml

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
                   assembly="BusinessObjectApp"
                   namespace="BusinessObjectApp.Modal">

    <!-- more mapping info here -->
    <class name="Company_Product" table="[Company_Product]">
        <id name="Id" column="Id">
            <generator class="native" />
        </id>
        <property name="SalesDate" column="SalesDate" />

        <!-- Many to many -->
        <many-to-one class="Company" name="Company" column="CompanyID" />
        <many-to-one class="Product" name="Product" column="ProductID" />
    </class>
</hibernate-mapping>

Product.hbm.xml

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
                   assembly="BusinessObjectApp"
                   namespace="BusinessObjectApp.Modal">

  <!-- more mapping info here -->
  <class name="Product" table="[Product]">
      <id name="Id" column="Id">
          <generator class="native" />
      </id>
      <property name="Name" column="Name" />
      <bag name="company_product" table="[Company_Product]" inverse="true" lazy="true">
          <key column="ProductID" />
          <one-to-many class="Company_Product" />
      </bag>
    </class>
</hibernate-mapping>

如果使用以下代码，我可以检索所有项目：

IList<Company_Product> test = session.QueryOver<Company_Product>()
.List<Company_Product>();

但是下面的代码会产生错误。我知道那是因为 Company_Product 类没有属性。我想将它们映射到相应的对象，如上面的输出。有可能吗？

string query = "SELECT C.Name, P.Name, CP.SalesDate FROM [Company_Product] CP " +
"LEFT JOIN [Company] C ON CP.CompanyID = C.Id " +
"LEFT JOIN [Product] P ON CP.ProductID = P.Id";

var test = session.CreateSQLQuery(query)
.SetResultTransformer(Transformers.AliasToBean<Company_Product>())
.List<Company_Product>();

更新：

现在我可以检索整个对象了。

Company_Product company_product = null;
Company company = null;
Product product = null;
IList<Company_Product> test = session.QueryOver<Company_Product>()
                    .Left.JoinAlias(cp => cp.Company, () => company)
                    .Left.JoinAlias(cp => cp.Product, () => product)
                    .SelectList(list => list
                        .Select(cp => cp.Company).WithAlias(() => company_product.Company)
                        .Select(cp => cp.Product).WithAlias(() => company_product.Product)
                        .Select(cp => cp.SalesDate).WithAlias(() => company_product.SalesDate)
                    )
                    .TransformUsing(Transformers.AliasToBean<Company_Product>())
                    .List<Company_Product>();

但我无法设置嵌套属性。

Company_Product company_product = null;
Company company = null;
Product product = null;
IList<Company_Product> test = session.QueryOver<Company_Product>()
                    .Left.JoinAlias(cp => cp.Company, () => company)
                    .Left.JoinAlias(cp => cp.Product, () => product)
                    .SelectList(list => list
                        .Select(cp => cp.Company.Name).WithAlias(() => company_product.Company.Name)
                        .Select(cp => cp.Product.Name).WithAlias(() => company_product.Product.Name)
                        .Select(cp => cp.SalesDate).WithAlias(() => company_product.SalesDate)
                    )
                    .TransformUsing(Transformers.AliasToBean<Company_Product>())
                    .List<Company_Product>();

谁能帮帮我？我是 Nhibernate 的新手，很抱歉我的英语不好。

Answer 1

您不需要使用本机 SQL 查询来实现此目的。 您可以使用 QueryOver，但必须使用投影。

session.QueryOver<Company_Product>()
       .JoinQueryOver<Company>(cp => cp.Company, ()=>companyAlias)
       .JoinQueryOver<Product>(cp => cp.Product, ()=>productAlias)
       .SelectList( l => l.Select( cp => companyAlias.Name)
                          .Select( cp => productAlias.Name)
                          .Select( cp => cp.SalesDate));

我还没有测试过它，自从我使用 NHibernate 以来已经一年多了，但它应该会为您指明正确的方向。 :)

另外，你为什么用包？我认为一套可能更合适。