JPA - 注入或实例化自定义属性/对象以进行 JSF 写访问？

发布于 2024-12-10 15:01:16 字数 522 浏览 0 评论 0原文

我正在使用 OpenJPA，想知道如何引用另一个自定义实体。假设有一个人和一个地址。两者都是我的建模实体。

Person 如何正确引用地址？

这样：

@Entity
public class Person {

    @Column
    @Inject
    Address adr;
}

或者像这样：

@Entity
public class Person {

    @Column
    Address adr = new Address();
}

我宁愿注入或实例化的原因是当我访问这样的地址时看到空指针异常：#{myBean.personA.adr.street} 因为当对象不是从现有记录加载而是在创建新记录时使用时，adr 返回 null

您如何解决实体中的这些问题？我错过了什么吗？顺便说一句：我使用 openJPA 和 Webbeans

原文

I am using OpenJPA and was wondering how to reference another custom entity. Let's assume there is a Person and an Address. Both are my modeled entities.

How would Person correctly refer to Address?

This way:

@Entity
public class Person {

    @Column
    @Inject
    Address adr;
}

or like this:

@Entity
public class Person {

    @Column
    Address adr = new Address();
}

The reason why I rather want to inject or instantiate is I see null pointer exception when I access Address like this: #{myBean.personA.adr.street}
because adr returns null when the object is not loaded from an existing record, but used when creating a new one

How do you solve auch issues in your entities? Am I missing sth.? BTW: I use openJPA and Webbeans

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幸福％小乖 2024-12-17 15:01:16

我会在您显式创建新的 Person 时创建它。

@ManagedBean
@ViewScoped
public class Register {

    private Person person;

    @PostConstruct
    public void init() {
        person = new Person();
        person.setAddress(new Address());
    }

    // ...
}

或者，也可以在 Person 中完成这项工作，这样您就不需要重复它

@ManagedBean
@ViewScoped
public class Register {

    private Person person;

    @PostConstruct
    public void init() {
        person = Person.create();
    }

    // ...
}

：

@Entity
public class Person {

    public static Person create() {
        Person person = new Person();
        person.setAddress(new Address());
        return person;
    }

    // ...
}

I would create it at the point where you're explicitly creating a new Person.

@ManagedBean
@ViewScoped
public class Register {

    private Person person;

    @PostConstruct
    public void init() {
        person = new Person();
        person.setAddress(new Address());
    }

    // ...
}

Or, alternatively, do the job in Person so that you don't need to repeat it:

@ManagedBean
@ViewScoped
public class Register {

    private Person person;

    @PostConstruct
    public void init() {
        person = Person.create();
    }

    // ...
}

with

@Entity
public class Person {

    public static Person create() {
        Person person = new Person();
        person.setAddress(new Address());
        return person;
    }

    // ...
}

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