使用条件和限制进行查询时，Hibernate 异常“无法解析属性”

Question

I have a OneToMany relation in hibernate defined like this:

@Entity
@Table(name = "groups")
public class Group extends BaseModel {// BaseModel defines id as @Id and @GeneratedValue

    @OneToMany
    @JoinColumn(name = "group_id")
    private List<User> users;

    // other fields, getters and setters omitted 
}


@Entity
@Table(name = "users")
public class User extends BaseModel {

    @ManyToOne
    @JoinColumn(name = "group_id")
    private Group group;

    // other fields, getters and setters omitted 
}

Column group_id is in the users table.
Calling methods Group.getUsers() and User.getGroup() work fine. But I also need to do a query after the column group_id :

Criteria criteria = Activator.getDefault().getSQLSession().createCriteria(User.class);
Criterion c = Restrictions.eq("group_id", 1); // an id of a group
criteria.add(c);

The Criterion object is created in a method, and it can be for other one-to-many tables or can contain other columns, so I can't use method getUsers() .

Unfortunatelly, the code above gives the following exception:

org.hibernate.QueryException: could not resolve property: group_id of: com.example.User
    at org.hibernate.persister.entity.AbstractPropertyMapping.propertyException(AbstractPropertyMapping.java:81)
    at org.hibernate.persister.entity.AbstractPropertyMapping.toType(AbstractPropertyMapping.java:75)
    at org.hibernate.persister.entity.AbstractEntityPersister.getSubclassPropertyTableNumber(AbstractEntityPersister.java:1482)
    at org.hibernate.persister.entity.BasicEntityPropertyMapping.toColumns(BasicEntityPropertyMapping.java:62)
    and so on ...

What could be the problem?

---

Edit:

After the change that user759837 suggested ( Criterion c = Restrictions.eq("group", 1); ), when I call criteria.list() , I get this error message: could not get a field value by reflection getter of com.example.Group.id

java.lang.IllegalArgumentException: Can not set java.lang.Long field com.example.BaseModel.id to java.lang.Long
    at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(Unknown Source)
    at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(Unknown Source)
    at sun.reflect.UnsafeFieldAccessorImpl.ensureObj(Unknown Source)
    at sun.reflect.UnsafeObjectFieldAccessorImpl.get(Unknown Source)
    at java.lang.reflect.Field.get(Unknown Source)
    at org.hibernate.property.DirectPropertyAccessor$DirectGetter.get(DirectPropertyAccessor.java:59)
    at org.hibernate.tuple.entity.AbstractEntityTuplizer.getIdentifier(AbstractEntityTuplizer.java:227)
    at org.hibernate.persister.entity.AbstractEntityPersister.getIdentifier(AbstractEntityPersister.java:3875)
    at org.hibernate.persister.entity.AbstractEntityPersister.isTransient(AbstractEntityPersister.java:3583)
    at org.hibernate.engine.ForeignKeys.isTransient(ForeignKeys.java:203)
    at org.hibernate.engine.ForeignKeys.getEntityIdentifierIfNotUnsaved(ForeignKeys.java:242)
    at org.hibernate.type.EntityType.getIdentifier(EntityType.java:456)
    at org.hibernate.type.ManyToOneType.nullSafeSet(ManyToOneType.java:130)
    ...

The BaseModel class is

@MappedSuperclass
public abstract class BaseModel {

    @Id
    @GeneratedValue
    private Long id;

    public Long getId() {
        return id;
    }

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

I tried with long id too, but it's the same error.

---

Edit 2:

After a lot of digging, it looks that the Criterion object should receive a group object as parameter, not an id: Restrictions.eq("group", {A_GROUP_OBJECT});

Could it be possible that I send there an id?

Answer 1

your column is group_id and you should use the property which is group ... Criterion c = Restrictions.eq(" group ", 1); // an id of a group...

Answer 2

This seems to work:

Criterion c = Restrictions.eq("group.id", 1); // an id of a group

Answer 3

If you are using oracle as your DB, the reason might be that group_id is a keyword in it.Change the name to something else and try.