NHibernate一对多映射

Question

I want to map one to many objects Person and PersonAddress

public class Person{
public virtual int Id {get; set;} public virtual string FirstName {get; set;}
public virtual ICollection<PersonAddress> PersonAddress { get; set; }}

public class PersonAddress{
public virtual int Id {get; set;}
public virtual int PersonId {get; set;}
...     }

I don't want to have person object property in address. It creates cyclic references and don't necessary for my application.

mapping file is like following:

<class name="Person"  table="Persons" >
    <id name="Id" type="Int32" column="PersonId">
        <generator class="identity"/>
    </id>
    <set name="PersonAddress" table="PersonAddress" lazy="true" fetch="join" outer-join="true" cascade="all-delete-orphan">
        <key column="PersonId"></key>
        <one-to-many class="PersonAddress"/>
    </set>  
</class>

<class name="PersonAddress"  table="PersonAddress" >
    <id name="Id" type="Int32" column="Id">
        <generator class="identity"/>
    </id>
    <property name="PersonId" column="PersonId" type="Int32"/>
    <property name="PhoneWork" column="PhoneWork" type="String"/>       
</class>

when trying to insert Person with person address I am receiving exception. Because it tries to insert PersonAddress with invalid id (default -1, 0, etc).

in samples that I have found it is specified back reference from child to parent

Answer 1

Try this:

public class Person {
    public virtual int Id { get; set; }
    public virtual string FirstName { get; set; }
    public virtual IList<PersonAddress> PersonAddress { get; set; }
    ... }

public class PersonAddress {
    public virtual int Id { get; set; }
    public virtual Person Person { get; set; }
    ... }

You should have a reference to the Person, and not just a PersonId. And if you have difficulties with the .hbm.xml mapping files, consider using Fluent NHibernate instead. Its automatic mapping feature works like a charm.

There is also a video series on NHibernate, which covers the subject pretty well.

Answer 2

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