java - Hibernate CreateCriteria 用于依赖类

Question

我正在开发一个应用程序，我必须在其中显示有关车辆详细信息的数据/信息。我有 2 个表 make 和 model，其中 make_id 是 model 表中的外键。我有 2 个实体类 Make 和 Model 如下所示:

@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
}

我能够检索所有 Make，但我的要求是仅检索 model_creation_date 之间的 Make今天和过去 30 天。任何人都可以帮助我如何为此建立 Hibernate 标准吗？

Answer 1

可能还有另一种解决方案，但要实现此目的，您需要修改 Make 类，如下所示，引入与 Model 类的新关系(@OneToMany):

@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
}

并保持“Model”类不变:

@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
}

一旦您与“Make”中的“Model”建立了关系，您就可以执行以下代码来获取结果:

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();