Java 如何在CriteriaAPI/JPQL中使用具有一对多属性的JPA投影

我很难使用CriteriaAPI创建一个查询，该API可以投影查询实体的属性并实例化DTO。其中一个投影属性将一对多关系映射到另一个实体，因此它是一组依赖实体。我正在使用fetch join检索集合。但我得到了以下错误：

org.hibernate.QueryException: query specified join fetching, but the owner of the fetched association was not present in the select list

我已经尝试过使用常规联接，但是在这种情况下，依赖实体集不会被填充。完全删除联接和/或获取也没有帮助

我使用的是JPA规范2.0、Hibernate 4.2.21.Final、Spring数据JPA 1.10.11.RELEASE。

有人能给我提些建议吗？我也会很高兴有一个工作的JPQL

这是我对查询的实现：

@Override
public List<EntityADto> findByPartialKey1OrderByPartialKey2(String partialKey1) {
    // Create query
    final CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
    final CriteriaQuery<EntityADto> criteriaQuery = criteriaBuilder.createQuery(EntityADto.class);

    // Define FROM clause
    final Root<EntityA> root = criteriaQuery.from(EntityA.class);
    root.fetch(EntityA_.oneToManyAttribute);

    // Define DTO projection
    criteriaQuery
            .select(criteriaBuilder.construct(
                    EntityADto.class,
                    root.get(EntityA_.id).get(EntityAId_.partialKey1),
                    root.get(EntityA_.id).get(EntityAId_.partialKey2),
                    root.get(EntityA_.stringAttribute1),
                    root.get(EntityA_.stringAttribute2),
                    root.get(EntityA_.oneToManyAttribute)))
            .orderBy(criteriaBuilder.asc(root.get(EntityA_.id).get(EntityAId_.partialKey2)))
            .distinct(true);

    // Define WHERE clause
    final ParameterExpression<String> parameterPartialKey1 = criteriaBuilder.parameter(String.class);
    criteriaQuery.where(criteriaBuilder.equal(root.get(EntityA_.id).get(EntityAId_.partialKey1), parameterPartialKey1));

    // Execute query
    final TypedQuery<EntityADto> typedQuery = entityManager.createQuery(criteriaQuery);
    typedQuery.setParameter(parameterPartialKey1, partialKey1);

    return typedQuery.getResultList();
}

@Entity
@Table(name = "TABLE_A", uniqueConstraints = 
@UniqueConstraint(columnNames = {
    "PARTIAL_KEY_1", "STRING_ATTR_1", "STRING_ATTR_2" }))
public class EntityA {
    @EmbeddedId
    @AttributeOverrides({
        @AttributeOverride(name = "partialKey1", column = @Column(name = "PARTIAL_KEY_1", nullable = false)),
        @AttributeOverride(name = "partialKey2", column = @Column(name = "PARTIAL_KEY_2", nullable = false))})
    private EntityAId id;
    @Column(name = "STRING_ATTR_1", nullable = false)
    private String stringAttribute1;
    @Column(name = "STRING_ATTR_2", nullable = false)
    private String stringAttribute2;
    @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "entityA")
    private Set<EntityB> entityBs;

    // getters and setters omitted for brevity.
}

@Entity
@Table(name = "TABLE_2")
public class EntityB {
    @EmbeddedId
    @AttributeOverrides({
        @AttributeOverride(name = "partialKey3", column = @Column(name = "PARTIAL_KEY_3", nullable = false)),
        @AttributeOverride(name = "partialKey1", column = @Column(name = "PARTIAL_KEY_1", nullable = false)),
        @AttributeOverride(name = "partialKey2", column = @Column(name = "PARTIAL_KEY_2", nullable = false))})
    private EntityBId id;
    @Column(name = "VALUE")
    private String value;
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumns({
        @JoinColumn(name = "PARTIAL_KEY_1", referencedColumnName = "PARTIAL_KEY_1", nullable = false, insertable = false, updatable = false),
        @JoinColumn(name = "PARTIAL_KEY_2", referencedColumnName = "PARTIAL_KEY_2", nullable = false, insertable = false, updatable = false)})
    private EntityA entityA;

    // getters and setters omitted for brevity.

public class EntityADto implements Serializable {
    private static final long serialVersionUID = -5343329086697620178L;

    private String partialKey1;
    private Integer partialKey2;
    private String stringAttribute1;
    private String stringAttribute2;
    private Map<String, String> additionalAttributes;

    public ProzessdatStandardDto() { }

    public ProzessdatStandardDto(String partialKey1,
                                 Integer partialKey2,
                                 String stringAttribute1,
                                 String stringAttribute2,
                                 Set<EntityB> entityBs) {
        this.partialKey1 = partialKey1;
        this.partialKey2 = partialKey2;
        this.stringAttribute1 = stringAttribute1;
        this.stringAttribute2 = stringAttribute2;

        final Map<String, String> entityBsConverted = new HashMap<>();
        if (!CollectionUtils.isEmpty(entityBs)) {
            for (EntityB entityB : entityBs) {
                entityBsConverted.put(entityB.getPartialKey3(), entityB.getValue());
            }
        }
        this.additionalAttributes = prozessdatExpansionsConverted;
    }

    // getters and setters omitted for brevity.
}

@覆盖
公共列表FindBypartialkey1或ByPartialkey2（字符串partialKey1）{
//创建查询
final CriteriaBuilder CriteriaBuilder=entityManager.getCriteriaBuilder（）；
final-CriteriaQuery-CriteriaQuery=criteriaBuilder.createQuery（EntityADto.class）；
//从子句定义
最终根=criteriaQuery.from（EntityA.class）；
root.fetch（EntityA_u2;oneToManyAttribute）；
//定义DTO投影
标准查询
.选择（criteriaBuilder.construct(
EntityADto.class，
root.get（EntityA.id）.get（EntityAId.partialKey1），
root.get（EntityA.id）.get（EntityAId.partialKey2），
root.get（EntityA_uu.stringAttribute1），
root.get（EntityA_uu.stringAttribute2），
root.get（EntityA_uu.oneToManyAttribute）））
.orderBy（criteriaBuilder.asc（root.get（EntityA_u2;.id）.get（EntityAId_2;u2b.partialKey2）））
.清晰（真实）；
//定义WHERE子句
最终参数expression参数partialkey1=criteriaBuilder.parameter（String.class）；
where（criteriaBuilder.equal（root.get（EntityA_u.id）.get（EntityAId_u.partialKey1），parameterPartialKey1））；
//执行查询
final-TypedQuery-TypedQuery=entityManager.createQuery（criteriaQuery）；
typedQuery.setParameter（parameterPartialKey1，partialKey1）；
返回typedQuery.getResultList（）；
}

实体如下所示：

@Override
public List<EntityADto> findByPartialKey1OrderByPartialKey2(String partialKey1) {
    // Create query
    final CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
    final CriteriaQuery<EntityADto> criteriaQuery = criteriaBuilder.createQuery(EntityADto.class);

    // Define FROM clause
    final Root<EntityA> root = criteriaQuery.from(EntityA.class);
    root.fetch(EntityA_.oneToManyAttribute);

    // Define DTO projection
    criteriaQuery
            .select(criteriaBuilder.construct(
                    EntityADto.class,
                    root.get(EntityA_.id).get(EntityAId_.partialKey1),
                    root.get(EntityA_.id).get(EntityAId_.partialKey2),
                    root.get(EntityA_.stringAttribute1),
                    root.get(EntityA_.stringAttribute2),
                    root.get(EntityA_.oneToManyAttribute)))
            .orderBy(criteriaBuilder.asc(root.get(EntityA_.id).get(EntityAId_.partialKey2)))
            .distinct(true);

    // Define WHERE clause
    final ParameterExpression<String> parameterPartialKey1 = criteriaBuilder.parameter(String.class);
    criteriaQuery.where(criteriaBuilder.equal(root.get(EntityA_.id).get(EntityAId_.partialKey1), parameterPartialKey1));

    // Execute query
    final TypedQuery<EntityADto> typedQuery = entityManager.createQuery(criteriaQuery);
    typedQuery.setParameter(parameterPartialKey1, partialKey1);

    return typedQuery.getResultList();
}

@Entity
@Table(name = "TABLE_A", uniqueConstraints = 
@UniqueConstraint(columnNames = {
    "PARTIAL_KEY_1", "STRING_ATTR_1", "STRING_ATTR_2" }))
public class EntityA {
    @EmbeddedId
    @AttributeOverrides({
        @AttributeOverride(name = "partialKey1", column = @Column(name = "PARTIAL_KEY_1", nullable = false)),
        @AttributeOverride(name = "partialKey2", column = @Column(name = "PARTIAL_KEY_2", nullable = false))})
    private EntityAId id;
    @Column(name = "STRING_ATTR_1", nullable = false)
    private String stringAttribute1;
    @Column(name = "STRING_ATTR_2", nullable = false)
    private String stringAttribute2;
    @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "entityA")
    private Set<EntityB> entityBs;

    // getters and setters omitted for brevity.
}

@Entity
@Table(name = "TABLE_2")
public class EntityB {
    @EmbeddedId
    @AttributeOverrides({
        @AttributeOverride(name = "partialKey3", column = @Column(name = "PARTIAL_KEY_3", nullable = false)),
        @AttributeOverride(name = "partialKey1", column = @Column(name = "PARTIAL_KEY_1", nullable = false)),
        @AttributeOverride(name = "partialKey2", column = @Column(name = "PARTIAL_KEY_2", nullable = false))})
    private EntityBId id;
    @Column(name = "VALUE")
    private String value;
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumns({
        @JoinColumn(name = "PARTIAL_KEY_1", referencedColumnName = "PARTIAL_KEY_1", nullable = false, insertable = false, updatable = false),
        @JoinColumn(name = "PARTIAL_KEY_2", referencedColumnName = "PARTIAL_KEY_2", nullable = false, insertable = false, updatable = false)})
    private EntityA entityA;

    // getters and setters omitted for brevity.

public class EntityADto implements Serializable {
    private static final long serialVersionUID = -5343329086697620178L;

    private String partialKey1;
    private Integer partialKey2;
    private String stringAttribute1;
    private String stringAttribute2;
    private Map<String, String> additionalAttributes;

    public ProzessdatStandardDto() { }

    public ProzessdatStandardDto(String partialKey1,
                                 Integer partialKey2,
                                 String stringAttribute1,
                                 String stringAttribute2,
                                 Set<EntityB> entityBs) {
        this.partialKey1 = partialKey1;
        this.partialKey2 = partialKey2;
        this.stringAttribute1 = stringAttribute1;
        this.stringAttribute2 = stringAttribute2;

        final Map<String, String> entityBsConverted = new HashMap<>();
        if (!CollectionUtils.isEmpty(entityBs)) {
            for (EntityB entityB : entityBs) {
                entityBsConverted.put(entityB.getPartialKey3(), entityB.getValue());
            }
        }
        this.additionalAttributes = prozessdatExpansionsConverted;
    }

    // getters and setters omitted for brevity.
}

@实体
@表（name=“Table_A”，唯一约束=
@唯一约束（列名称={
“部分键1”、“字符串属性1”、“字符串属性2”}）
公共类实体{
@嵌入ID
@属性溢出({
@AttributeOverride（name=“partialKey1”，column=@column（name=“PARTIAL\u KEY\u 1”，nullable=false）），
@AttributeOverride（name=“partialKey2”，column=@column（name=“PARTIAL\u KEY\u 2”，nullable=false）））
私人实体id；
@列（name=“STRING\u ATTR\u 1”，null=false）
私有字符串stringAttribute1；
@列（name=“STRING\u ATTR\u 2”，null=false）
私有字符串stringAttribute2；
@OneToMany（cascade=CascadeType.ALL，fetch=FetchType.LAZY，mappedBy=“entityA”）
私有集合实体；
//为简洁起见，省略了getter和setter。
}
@实体
@表（name=“表2”）
公共类实体B{
@嵌入ID
@属性溢出({
@AttributeOverride（name=“partialKey3”，column=@column（name=“PARTIAL\u KEY\u 3”，nullable=false）），
@AttributeOverride（name=“partialKey1”，column=@column（name=“PARTIAL\u KEY\u 1”，nullable=false）），
@AttributeOverride（name=“partialKey2”，column=@column（name=“PARTIAL\u KEY\u 2”，nullable=false）））
私人实体投标id；
@列（name=“VALUE”）
私有字符串值；
@manytone（fetch=FetchType.LAZY）
@连接柱({
@JoinColumn（name=“PARTIAL\u KEY\u 1”，referencedColumnName=“PARTIAL\u KEY\u 1”，nullable=false，insertable=false，updateable=false），
@JoinColumn（name=“PARTIAL\u KEY\u 2”，referencedColumnName=“PARTIAL\u KEY\u 2”，nullable=false，insertable=false，updateable=false）}）
私人实体a实体a；
//为简洁起见，省略了getter和setter。

}

最后是DTO:

@Override
public List<EntityADto> findByPartialKey1OrderByPartialKey2(String partialKey1) {
    // Create query
    final CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
    final CriteriaQuery<EntityADto> criteriaQuery = criteriaBuilder.createQuery(EntityADto.class);

    // Define FROM clause
    final Root<EntityA> root = criteriaQuery.from(EntityA.class);
    root.fetch(EntityA_.oneToManyAttribute);

    // Define DTO projection
    criteriaQuery
            .select(criteriaBuilder.construct(
                    EntityADto.class,
                    root.get(EntityA_.id).get(EntityAId_.partialKey1),
                    root.get(EntityA_.id).get(EntityAId_.partialKey2),
                    root.get(EntityA_.stringAttribute1),
                    root.get(EntityA_.stringAttribute2),
                    root.get(EntityA_.oneToManyAttribute)))
            .orderBy(criteriaBuilder.asc(root.get(EntityA_.id).get(EntityAId_.partialKey2)))
            .distinct(true);

    // Define WHERE clause
    final ParameterExpression<String> parameterPartialKey1 = criteriaBuilder.parameter(String.class);
    criteriaQuery.where(criteriaBuilder.equal(root.get(EntityA_.id).get(EntityAId_.partialKey1), parameterPartialKey1));

    // Execute query
    final TypedQuery<EntityADto> typedQuery = entityManager.createQuery(criteriaQuery);
    typedQuery.setParameter(parameterPartialKey1, partialKey1);

    return typedQuery.getResultList();
}

@Entity
@Table(name = "TABLE_A", uniqueConstraints = 
@UniqueConstraint(columnNames = {
    "PARTIAL_KEY_1", "STRING_ATTR_1", "STRING_ATTR_2" }))
public class EntityA {
    @EmbeddedId
    @AttributeOverrides({
        @AttributeOverride(name = "partialKey1", column = @Column(name = "PARTIAL_KEY_1", nullable = false)),
        @AttributeOverride(name = "partialKey2", column = @Column(name = "PARTIAL_KEY_2", nullable = false))})
    private EntityAId id;
    @Column(name = "STRING_ATTR_1", nullable = false)
    private String stringAttribute1;
    @Column(name = "STRING_ATTR_2", nullable = false)
    private String stringAttribute2;
    @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "entityA")
    private Set<EntityB> entityBs;

    // getters and setters omitted for brevity.
}

@Entity
@Table(name = "TABLE_2")
public class EntityB {
    @EmbeddedId
    @AttributeOverrides({
        @AttributeOverride(name = "partialKey3", column = @Column(name = "PARTIAL_KEY_3", nullable = false)),
        @AttributeOverride(name = "partialKey1", column = @Column(name = "PARTIAL_KEY_1", nullable = false)),
        @AttributeOverride(name = "partialKey2", column = @Column(name = "PARTIAL_KEY_2", nullable = false))})
    private EntityBId id;
    @Column(name = "VALUE")
    private String value;
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumns({
        @JoinColumn(name = "PARTIAL_KEY_1", referencedColumnName = "PARTIAL_KEY_1", nullable = false, insertable = false, updatable = false),
        @JoinColumn(name = "PARTIAL_KEY_2", referencedColumnName = "PARTIAL_KEY_2", nullable = false, insertable = false, updatable = false)})
    private EntityA entityA;

    // getters and setters omitted for brevity.

public class EntityADto implements Serializable {
    private static final long serialVersionUID = -5343329086697620178L;

    private String partialKey1;
    private Integer partialKey2;
    private String stringAttribute1;
    private String stringAttribute2;
    private Map<String, String> additionalAttributes;

    public ProzessdatStandardDto() { }

    public ProzessdatStandardDto(String partialKey1,
                                 Integer partialKey2,
                                 String stringAttribute1,
                                 String stringAttribute2,
                                 Set<EntityB> entityBs) {
        this.partialKey1 = partialKey1;
        this.partialKey2 = partialKey2;
        this.stringAttribute1 = stringAttribute1;
        this.stringAttribute2 = stringAttribute2;

        final Map<String, String> entityBsConverted = new HashMap<>();
        if (!CollectionUtils.isEmpty(entityBs)) {
            for (EntityB entityB : entityBs) {
                entityBsConverted.put(entityB.getPartialKey3(), entityB.getValue());
            }
        }
        this.additionalAttributes = prozessdatExpansionsConverted;
    }

    // getters and setters omitted for brevity.
}

公共类EntityADto实现可序列化{ 私有静态最终长serialVersionUID=-5343329086697620178L； 私有字符串partialKey1； 私有整数partialKey2； 私有字符串stringAttribute1； 私有字符串stringAttribute2； 私有地图附加属性； 公共ProzessdatStandardDto（）{} 公共项目DATStandardDTO（字符串partialKey1， 整数partialKey2， 字符串stringAttribute1， 字符串stringAttribute2， 设置实体（b）{ this.partialKey1=partialKey1； this.partialKey2=partialKey2； this.stringAttribute1=stringAttribute1； this.stringAttribute2=stringAttribute2； 最终映射entityBsConverted=新HashMap（）； 如果（！CollectionUtils.isEmpty（entityBs））{ for（EntityB EntityB:entityBs）{ entityBsConverted.put（entityB.getPartialKey3（），entityB.getValue（））； } } this.additionalAttributes=prozessDateExpansConverted； } //为简洁起见，省略了getter和setter。 }

---

联接为您提供了一组行，结果为sql:

Parent    Child
p1        c1
p1        c2
p1        c3

等等。没有将结果集合传递到构造函数的机制

JPA规范4.14

constructor_expression ::=
NEW constructor_name ( constructor_item {, constructor_item}* )

constructor_item ::=
single_valued_path_expression |
scalar_expression |
aggregate_expression |
identification_variable

另外，另一个问题是查询可能返回多个父级或子级

Parent    Child    Child2
p1        c111     c121
p1        c121     
p1        c131     c122
p2        c211     c211
p2        c221     c212
p2        c231     

我猜原因是，对于底层的JPA提供者来说，这变得太复杂了，他们不知道在哪里拆分它，或者使用哪些值传递给子构造函数，或者我不熟悉的更微妙的原因。一句话，它要求您提供解析这个矩阵的代码，如果您要这样做，您最好只解析结果而不使用JPA。

C