Java Hibernate Criteria：在子查询/DetachedCriteria 中执行 JOIN

Hibernate Criteria: Perform JOIN in Subquery/DetachedCriteria

提问by Gilean

I'm running into an issue with adding JOIN's to a subquery using DetachedCriteria. The code looks roughly like this:

我在使用 DetachedCriteria 将 JOIN 添加到子查询时遇到了问题。代码大致如下：

Criteria criteria = createCacheableCriteria(ProductLine.class, "productLine");
criteria.add(Expression.eq("productLine.active", "Y"));

DetachedCriteria subCriteria = DetachedCriteria.forClass(Model.class, "model");
subCriteria.setProjection(Projections.rowCount());
subCriteria.createAlias("model.modelLanguages", "modelLang");
subCriteria.createAlias("modelLang.language", "lang");
criteria.add(Expression.eq("lang.langCode", "EN"));
subCriteria.add(Restrictions.eqProperty("model.productLine.productLineId","productLine.productLineId"));
criteria.add(Subqueries.lt(0, subCriteria));

But the logged SQL does not contain the JOIN in the subquery, but does include the alias which is throwing an error

但是记录的 SQL 不包含子查询中的 JOIN，但包含抛出错误的别名

SELECT *
FROM PRODUCT_LINE this_
WHERE this_.ACTIVE=?
AND ?                  <
  (SELECT COUNT(*) AS y0_
  FROM MODEL this0__
  WHERE lang3_.LANG_CODE      ='EN'
  AND this0__.PRODUCT_LINE_ID     =this_.ID
  )

How can I add the joins to the DetachedCriteria?

如何将连接添加到 DetachedCriteria？

---

---

@Entity
@Table(name = "PRODUCT_LINE")
public class ProductLine implements java.io.Serializable {

    private long productLineId;
    private char active;
    private Set<Models> models = new HashSet<Models>(0);

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "productLine")
    public Set<Models> getModels() {
        return this.models;
    }

}

@Entity
@Table(name = "MODEL")
public class Model implements java.io.Serializable {

    private long modelId;
    private ProductLine productLine;
    private String name;
    private Set<ModelLanguages> modelLanguages = new HashSet<ModelLanguages>(0);

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "PRODUCT_LINE_ID")
    public ProductLine getProductLine() {
        return this.productLine;
    }

    @Column(name = "NAME", nullable = false)
    public String getName() {
        return this.name;
    }

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "model")
    public Set<ModelLanguages> getModelLanguages() {
        return this.modelLanguages;
    }

}

@Entity
@Table(name = "MODEL_LANGUAGES")
public class ModelLanguages implements java.io.Serializable {

    private long id;
    private Language language;
    private Model model;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "LANGUAGE_ID", nullable = false, insertable = false, updatable = false)
    public Language getLanguage() {
        return this.language;
    }

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "MODEL_ID", nullable = false, insertable = false, updatable = false)
    public Model getModel() {
        return this.model;
    }
}


@Entity
@Table(name = "LANGUAGES", uniqueConstraints = @UniqueConstraint(columnNames = "LANG_CODE"))
public class Language implements java.io.Serializable {

    private long languageId;
    private String langCode;
    private Set<ModelLanguages> modelLanguages = new HashSet<ModelLanguages>(
            0);

    @Column(name = "LANG_CODE", unique = true, nullable = false)
    public String getLangCode() {
        return this.langCode;
    }

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "language")
    public Set<ModelLanguages> getModelLanguages() {
        return this.modelLanguages;
    }
}

Hibernate version: 3.2.6.ga
Hibernate core: 3.3.2.GA
Hibernate annotations: 3.4.0.GA
Hibernate commons-annotations: 3.3.0.ga
Hibernate entitymanager: 3.4.0.GA
Hibernate validator: 3.1.0.GA

回答by Thierry

Don't you have a typo in your code at the following line :

您在以下行的代码中是否有拼写错误：

criteria.add(Expression.eq("lang.langCode", "EN"));

I think, you should add this restriction on the subcriteria and not the criteria.

我认为，您应该在子标准而不是标准上添加此限制。

回答by stviper

If you need to join tables in subquery can you try make this. It is explicitly specifying joinType in your detached criteria.

如果您需要在子查询中连接表，您可以尝试进行此操作。它在您的分离条件中明确指定了 joinType。

subCriteria.createAlias("model.modelLanguages", "modelLang", CriteriaSpecification.LEFT_JOIN);
subCriteria.createAlias("modelLang.language", "lang", CriteriaSpecification.LEFT_JOIN);