Question

我正在使用带有Hibernate 4.x的JPA 2.1。我发现@MakKeyColumn不是在打瞌睡。

@Entity
public class Department {
    @Id private int id;

    @OneToMany(mappedBy = "department")
    @MapKeyColumn(name = "cub_id")
    private Map<String, Employee> employeesByCubicle = new HashMap<>();

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public Map<String, Employee> getEmployeesByCubicle() {
        return employeesByCubicle;
    }

    public void setEmployeesByCubicle(Map<String, Employee> employeesByCubicle) {
        this.employeesByCubicle = employeesByCubicle;
    }
}

如果执行上面的代码，我可以看到以下错误

Caused by: org.postgresql.util.PSQLException: ERROR: null value in column "cub_id" violates not-null constraint
  Detail: Failing row contains (2, xxxxxx, null, null).

但是，如果我省略@MapKeyColumn，它就可以了。任何人都可以告诉我为什么在使用@MapKeyColumn

时它无法正常工作

感谢您提前回复：）

Answer 1

尝试将MapKeyColumn定义为可为空：

from django.conf.urls import include, url

from .app_views import index

urlpatterns = [
    url(r'^.*$', index, name='app'),
]

可以为null的属性的默认值为＆＃39; false＆＃39;。

@MapKeyColumn（name =＆＃34; XXX＆＃34;）无效

1 个答案: