Hibernate CreateCriteria for dependent class

Question

I am working on an application where I have to display data/information about the vehicle details. I have 2 tables make and model with make_id being the foreign key in model table. I have 2 entity classes Make and Model as shown below:

@Entity
@Table(name = "make")
@PrimaryKeyJoinColumn(name="make_id")
public class Make {
    @Id
    @Column(name = "make_id")
    private String makeId;

    @Column(name = "make_name")
    private String makeName;

    @ManyToOne
    @JoinColumn(name = "mfg_unit_id")
    private MfgUnit mfgUnit;

    // Getter and Setters
}


@Entity
@Table(name = "model")
public class Model {
    @Id
    @Column(name = "model_id")
    private String modelId;

    @Column(name = "model_creation_date")
    private Date modelCreationDate;

    @Column(name = "make_id")
    private long makeId;

    @ManyToOne
    @JoinColumn(name = "make_id")
    private Make make;

    // Getter and Setters
}

I am able to retrieve all the Makes, but my requirement is to only retrieve the Makes for which the model_creation_date is between today and last 30 days. Can anyone help me with how to build the Hibernate criteria for this?

Answer 1

there can be another solution, but to achieve this you need to modify your Make class as following introducing a new relationship (@OneToMany) with Model class:

@Entity
@Table(name = "make")
@PrimaryKeyJoinColumn(name="make_id")
public class Make {
    @Id
    @Column(name = "make_id")
    private String makeId;

    @Column(name = "make_name")
    private String makeName;

    // ** introduced new relationship **
    @OneToMany(mappedBy="make", fetch = FetchType.LAZY)
    private List<Model> models;

    @ManyToOne
    @JoinColumn(name = "mfg_unit_id")
    private MfgUnit mfgUnit;

    // Getter and Setters
}

And keep the 'Model' class as it is:

@Entity
@Table(name = "model")
public class Model {
    @Id
    @Column(name = "model_id")
    private String modelId;

    // change the datatype as Date or similar Datatype
    @Column(name = "model_creation_date")
    private Date modelCreationDate;

    @Column(name = "make_id")
    private long makeId;

    @ManyToOne
    @JoinColumn(name = "make_id")
    private Make make;

    // Getter and Setters
}

Once you have the relationship with 'Model' from 'Make' you can execute the following code to get your result:

Calendar cal = Calendar.getInstance();
// today 
Date toDate=cal.getTime(); 
cal.add( Calendar.DATE, -30 );
//date before 30 days
Date fromDate=cal.getTime();


Criteria criteria = session.createCriteria(Make.class , "m")
        .createAlias("models", "s")
        .add(Restrictions.between("s.modelCreationDate",  fromDate, toDate))
        // if the above condition dosen't give you exact result you may try following(2)
        // try gt or lt ... as needed 
        //.add(Restrictions.ge("publicationDate", fromDate)) 
        //.add(Restrictions.le("publicationDate", fromDate))
        .setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);

List<Make> ll2 = criteria.list();