映射一对多单向关系

Question

Considering these tables as example, where each person can have multiple address es.

CREATE TABLE person (
    id INTEGER NOT NULL PRIMARY KEY,
    name VARCHAR(100) NOT NULL
);

CREATE TABLE address (
    id INTEGER NOT NULL PRIMARY KEY,
    address VARCHAR(100) NOT NULL,
    city VARCHAR(100) NOT NULL,
    person_id INTEGER NOT NULL
);

I would like to map these tables to JPA entities, but I wouldn't like to map a bidirectional relationship between them using mappedBy .

What's the proper way to map a OneToMany unidirectional relationship between Person and Address ? Considering that the Person must know their Address es, but the Address must not know the Person it belongs to.

Answer 1

You can do it using annotations JoinColumn and ManyToOne in Person Entity.

    @OneToMany(cascade = CascadeType.ALL,orphanRemoval = true)
@JoinColumn(name = "person_pkey")
public List<Address> getAddresses() {
    return addresses;
}

Answer 2

You don't need to make it bidirectional. You can simply place the @OneToMany annotation on you collection-typed field in Person and specify the JoinColumn of the address table.

See here , Example 3. I think that's what you're looking for.

So you will have something like:

// In Person class:

@OneToMany
@JoinColumn(name="person_id")
public Set<Address> getAddresses() {return addresses;}

No mappedBy attribute, no bidirectional mapping.