我正在尝试使用 DataNucleus 2.1.1 将 Employee 对象插入数据库，但在执行“插入”准备语句之前未设置外键位置参数。我在做什么阻止设置参数？我是不是遗漏了什么？阅读效果很好。
DEBUG [DataNucleus.Datastore.Native] - INSERT INTO MYSCHEMA.EMPLOYEE ("NAME",POSITION_ID,ID) VALUES (<'John Doe'>,<UNPRINTABLE>,<100>)
WARN [DataNucleus.Datastore.Persist] - Insert of object "com.example.staff.Employee@50 7895d8" using statement "INSERT INTO MYSCHEMA.EMPLOYEE ("NAME",POSITION_ID,ID) VALUES (?,?,?)" failed : Invalid operation: parameter 2 not set or registered
PersistenceManager pm = // obtain PersistenceManager
Position position = // obtain Position using pm (I can post this code upon request)
Employee employee =new Employee(100, "John Doe", position);
pm.makePersistent(employee);
pm.close();
<jdo>
<package name="com.example.staff">
<class name="Position" identity-type="application" schema="MYSCHEMA" table="Position">
<inheritance strategy="new-table"/>
<field name="id" primary-key="true" persistence-modifier="persistent" default-fetch-group="true">
<column name="ID" jdbc-type="integer"/>
</field>
<field name="title" persistence-modifier="persistent" default-fetch-group="true">
<column name="TITLE" jdbc-type="varchar"/>
</field>
</class>
</package>
</jdo>
<jdo>
<package name="com.example.staff">
<class name="Employee" identity-type="application" schema="MYSCHEMA" table="EMPLOYEE">
<inheritance strategy="new-table"/>
<field name="id" primary-key="true" persistence-modifier="persistent" default-fetch-group="true">
<column name="ID" jdbc-type="integer"/>
</field>
<field name="name" persistence-modifier="persistent" default-fetch-group="true">
<column name="NAME" jdbc-type="varchar"/>
</field>
<field name="position" persistence-modifier="persistent" default-fetch-group="true">
<column name="POSITION_ID" jdbc-type="integer" />
</field>
</class>
</package>
</jdo>
@PersistenceCapable
public class Employee extends Object {
private Integer id;
private String name;
private Position position;
public Employee(Integer id, String name, Position position) {
this.id =id;
this.name =name;
this.position =position;
}
}
@PersistenceCapable
public class Position extends Object {
private Integer id;
private String title;
}