插入值时的 SCOPE_IDENTITY

Question

我在尝试执行我的 ORM 程序时收到此错误消息。

NHibernate.Exceptions.GenericADOException: '无法插入： [NHibernateWinFormsApp.Employee][SQL: INSERT INTO Employee DEFAULT 价值观；选择 SCOPE_IDENTITY()]'

这是我的映射文件编辑

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

  <class name="Employee">
    <id name="EmployeeId" column="EmployeeId">
      <column name="EmployeeId" not-null="true" />
      <column name="FirstName" />
      <column name="LastName" />
      <generator class="native"/>
    </id>

    <bag name="Department" table="EmployeeDepartment" >
      <key column="EmployeeId" not-null="true" />
      <many-to-many class="Department" column="DepartmentId"/>
    </bag>
  </class>

  <class name="Department">
    <id name="DepartmentId">
      <column name="DepartmentId" not-null="true" />
      <column name="DepartmentName" />
      <generator class="native"/>
    </id>

    <bag name="Employee" table="EmployeeDepartment" inverse="true">
      <key column="DepartmentId" not-null="true"/>
      <many-to-many class="Employee" column="EmployeeId"/>
    </bag>
    <property name="DepartmentName" type="string"/>
  </class>

</hibernate-mapping>

然后，进入我的会话：

DepartmentRepository departmentRepository = new DepartmentRepository(session);

// get department by id
Department department = departmentRepository.GetById(int.Parse(textDepartment.Text));
employeeData.Department = new List<Department>();
employeeData.Department.Add(department);
department.Employee.Add(employeeData);

有人知道如何解决这个小问题吗？

Answer 1

您似乎没有映射一些必须在两条记录之间具有不同值的列。所以他们总是插入null，但你只能有一个这样的员工，导致所有其他插入失败。

要么删除该约束，要么放松它（通过将其替换为忽略null 值的过滤唯一索引），或者将这些列映射到某些属性并为每个员工赋予它们唯一值。

但是，您的问题的底线是：始终咨询所有 InnerException 及其特定属性（如果有）。这不是 NHibernate 特定的建议，您应该在遇到的所有异常情况下都这样做。