我想基于modelB中的用户从modelA中获取数据。但是对于每条记录我都必须在modelB中有记录不是强制性的。因此,当我使用下面的代码来获取数据时,它返回0条记录。
BooleanExpression searchCriteria = searchCriteria
.and(
qModelA.modelb.user.id.eq(userId)
)
.and ( some other conditions as well);
modelA.findAll(searchCriteria, pageable);
当我调试时,我发现QueryDsl放置了交叉连接。谁能告诉我如何解决此问题,querydsl是否有任何方法可以添加左联接而不是交叉联接?下面是我的两个模型。
@Entity
public class ModelA implements Serializable {
private Long id;
private String label;
private ModelB modelB;
@Id
@SequenceGenerator(name = "modelASeq", sequenceName = "modela_id_seq", allocationSize = 1)
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "modelASeq")
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
@Column(length = 150, nullable = false)
public String getLabel() {
return label;
}
public void setLabel(String label) {
this.label = label;
}
@OneToOne(mappedBy = "modelA", cascade = CascadeType.REMOVE)
public ModelB getModelB() {
return modelB;
}
public void setModelB(ModelB modelB) {
this.modelB = modelB;
}
}
@Entity
public class ModelB implements Serializable {
private Long id;
private User user;
private ModelA modelA;
@Id
@SequenceGenerator(name = "modelBSeq", sequenceName = "modelb_id_seq", allocationSize = 1)
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "modelBSeq")
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
@NotNull
@ManyToOne
@JoinColumn(name = "user_id", nullable = false )
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
@NotNull
@OneToOne
@JoinColumn(name = "modela_id", nullable = false)
public ModelA getModelA() {
return modelA;
}
public void setModelA(ModelA modelA) {
this.modelA = modelA;
}
}
最佳答案
如果需要左连接,则需要使用显式连接:
query.from(modelA)
.leftJoin(modelA.modelB, modelB)
...