FluenNHibernate .Formula("...")不工作

Question

我在AutoMapping中使用FluentNHibernate。不使用自定义约定或更改。NHibernate和FluentNHibernate程序集都是最新版本。数据库为Sqlite3

我尝试使用以下实体(每个层次结构的表)：

public abstract class Unit
{
  public virtual int Id { get; set; }
  public virtual string Name { get; set; }
}

public class Employee : Unit
{       
  public Employee()
  {
    this.Groups = new List<Group>();
  }

  public virtual IList<Group> Groups { get; private set; }      
}

public class Group : Unit
{
  public Group ()
  {
    this.Employees = new List<Employee>();
  }

  public virtual int EmployeesCount { get; set; }

  public virtual IList<Employee> Employees { get; private set; }

}   

public class GroupAutoMappingOverride : IAutoMappingOverride<Group>
{
  public void Override (AutoMapping<Group> mapping)
  {
    mapping.Map(g => g.EmployeesCount).Formula("count(*)");
  }
}

我自动生成模式。一切都很好：

create table "Unit" (
  Id  integer,
  TypeId TEXT not null, //discriminator column
  Name TEXT,
  primary key (Id)
)

create table EmployeesToGroups (
  Employee_id INTEGER not null,
  Group_id INTEGER not null
)

我检查了自动生成的映射：

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
  <class xmlns="urn:nhibernate-mapping-2.2" name="App.Models.Entities.Unit, App, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null" table="`Unit`">
    <id name="Id" type="System.Int32, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
      <column name="Id" />
      <generator class="identity" />
    </id>
    <discriminator type="String">
      <column name="TypeId" />
    </discriminator>
    <property name="Name" type="System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
      <column name="Name" />
    </property>
   <subclass name="App.Models.Entities.Employee, App, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null">
      <bag access="backfield" name="Groups" table="GroupToEmployee">
        <key>
          <column name="Employee_id" />
        </key>
        <many-to-many class="App.Models.Entities.Group, App, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null">
          <column name="Group_id" />
        </many-to-many>
      </bag>      
    </subclass>
    <subclass name="App.Models.Entities.Group, App, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null">
      <bag access="backfield" inverse="true" name="Employees" table="EmployeeToGroup">
        <key>
          <column name="Group_id" />
        </key>
        <many-to-many class="App.Models.Entities.Employee, App, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null">
          <column name="Employee_id" />
        </many-to-many>
      </bag>
      <property name="EmployeesCount" type="System.Int32, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
        <column name="EmployeesCount" />
      </property>
    </subclass>
  </class>
</hibernate-mapping>

嗯..。没有公式。当我尝试从group中获取所有记录时，我得到一个异常：

SQLite error
no such column: group0_.EmployeesCount

生成的查询错误：

NHibernate: select group0_.Id as Id6_, group0_.Name as Name6_, **group0_.EmployeesCount** as Employee9_6_ from "Unit" group0_ where group0_.TypeId='App.Models.Entities
.Group'

怎么了？它应该是有效的吗？

Answer 1

您的映射覆盖似乎没有被考虑在内。如果是这样的话，您应该会在映射文件中看到类似以下内容：

<property name="EmployeesCount" formula="count(*)" type="System.Int32, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />

在构建如下映射时，是否包含了映射覆盖：

“要使用重写，您需要指示您的AutoMap实例使用它们。通常，这将在流畅的配置设置的上下文中完成，但我将仅使用AutoMap本身进行说明。”

AutoMap.AssemblyOf<Person>(cfg)
  .UseOverridesFromAssemblyOf<PersonMappingOverride>();

以上内容摘自http://wiki.fluentnhibernate.org/Auto_mapping#Overrides