如何使用Criteria Builder正确创建嵌套连接

时间：2012-05-07 21:55:23

标签： jpa join nested eclipselink

我有三个实体学校，部门，计划，每当我尝试加入其中两个实体时，第三个实体会被引用，所以我正在寻找一个使用条件构建器的示例，了解如何正确启动 Root＆lt;＆gt; 实体并正确加入。

我的学校实体是造成问题的原因。

public class School {

@NotNull
private String name;

@NotNull
private String code;

@OneToMany(cascade = CascadeType.ALL, mappedBy = "schoolDepartment")
private Set<Department> departments = new HashSet<Department>();

@OneToMany(cascade = CascadeType.ALL, mappedBy = "school")
private Set<Program> programs = new HashSet<Program>();
}

计划实体 

public class Program {

@NotNull
@Size(min = 0, max = 300)
private String name;

@NotNull
@Size(min = 0)
private String description;

private String code;

@Enumerated(EnumType.STRING)
private ProgramType programType;

@ManyToOne
private School school;

我的尝试失败只加入上面的两个实体，EclipseLink会引用第三个？

    // FROM program JOIN School 
Root<Program> program = cq.from(Program.class);

Join<School,Program> school =  program.join("school" , JoinType.INNER);
            //Join<School, Department> departmentJoin =    school.join("schoolDepartment", JoinType.LEFT);

             // SELECT task as Task, person as Person, ... 
             cq.multiselect(program,school);
             return program;  // EclipseLink requires a joined entity for the count

包含SQL生成的完整堆栈跟踪。请注意它如何开始引用School实体，然后在Department实体上调用ReadAllObjectQuery？

[EL Fine]: sql: 2012-05-06 17:34:52.886--ServerSession(1839972036)--Connection(131165903)--Thread(Thread["http-bio-8080"-exec-3,5,main])--SELECT t0.id, t0.CODE, t0.NAME, t0.version, t1.programID, t1.ACTIVE, t1.CODE, t1.DESCRIPTION, t1.NAME, t1.PROGRAMTYPE, t1.REQUIREDCREDITS, t1.version, t1.SCHOOL_id FROM SCHOOL t0 LEFT OUTER JOIN PROGRAM t1 ON (t1.SCHOOL_id = t0.id), SCHOOL t2 WHERE (t2.id = t1.SCHOOL_id)
[EL Finest]: connection: 2012-05-06 17:34:52.888--ServerSession(1839972036)--Connection(354961667)--Thread(Thread["http-bio-8080"-exec-3,5,main])--Connection released to connection pool [read].
2012-05-06 17:34:52,896 ["http-bio-8080"-exec-3] DEBUG org.springframework.beans.factory.annotation.InjectionMetadata - Processing injected method of bean 'org.bixin.dugsi.domain.School': PersistenceElement for transient javax.persistence.EntityManager org.bixin.dugsi.domain.School.entityManager
2012-05-06 17:34:52,896 ["http-bio-8080"-exec-3] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'entityManagerFactory'
2012-05-06 17:34:52,899 ["http-bio-8080"-exec-3] DEBUG org.springframework.beans.factory.annotation.InjectionMetadata - Processing injected method of bean 'org.bixin.dugsi.domain.School': PersistenceElement for transient javax.persistence.EntityManager org.bixin.dugsi.domain.School.entityManager
2012-05-06 17:34:52,900 ["http-bio-8080"-exec-3] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'entityManagerFactory'
2012-05-06 17:34:52,901 ["http-bio-8080"-exec-3] DEBUG org.springframework.beans.factory.annotation.InjectionMetadata - Processing injected method of bean 'org.bixin.dugsi.domain.School': PersistenceElement for transient javax.persistence.EntityManager org.bixin.dugsi.domain.School.entityManager
2012-05-06 17:34:52,901 ["http-bio-8080"-exec-3] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'entityManagerFactory'
2012-05-06 17:34:52,902 ["http-bio-8080"-exec-3] DEBUG org.springframework.beans.factory.annotation.InjectionMetadata - Processing injected method of bean 'org.bixin.dugsi.domain.Program': PersistenceElement for transient javax.persistence.EntityManager org.bixin.dugsi.domain.Program.entityManager
2012-05-06 17:34:52,903 ["http-bio-8080"-exec-3] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'entityManagerFactory'
[EL Finest]: query: 2012-05-06 17:34:52.904--ServerSession(1839972036)--Thread(Thread["http-bio-8080"-exec-3,5,main])--Execute query ReadObjectQuery(name="school" referenceClass=School )
2012-05-06 17:34:52,908 ["http-bio-8080"-exec-3] DEBUG org.springframework.beans.factory.annotation.InjectionMetadata - Processing injected method of bean 'org.bixin.dugsi.domain.Program': PersistenceElement for transient javax.persistence.EntityManager org.bixin.dugsi.domain.Program.entityManager
2012-05-06 17:34:52,908 ["http-bio-8080"-exec-3] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'entityManagerFactory'
[EL Finest]: transaction: 2012-05-06 17:34:52.908--UnitOfWork(2138845270)--Thread(Thread["http-bio-8080"-exec-3,5,main])--[EL Finest]: query: 2012-05-06 17:34:52.91--ServerSession(1839972036)--Thread(Thread["http-bio-8080"-exec-3,5,main])--Execute query ReadAllQuery(name="departments" referenceClass=Department )
[EL Finest]: connection: 2012-05-06 17:34:52.911--ServerSession(1839972036)--Connection(32490450)--Thread(Thread["http-bio-8080"-exec-3,5,main])--Connection acquired from connection pool [read].
[EL Finest]: connection: 2012-05-06 17:34:52.911--ServerSession(1839972036)--Thread(Thread["http-bio-8080"-exec-3,5,main])--reconnecting to external connection pool
[EL Fine]: sql: 2012-05-06 17:34:52.912--ServerSession(1839972036)--Connection(606146812)--Thread(Thread["http-bio-8080"-exec-3,5,main])--SELECT id, ACTIVE, CODE, DESCRIPTION, NAME, version, SCHOOLDEPARTMENT_id FROM DEPARTMENT WHERE (SCHOOLDEPARTMENT_id = ?)
    bind => [1]
[EL Finest]: connection: 2012-05-06 17:34:52.913--ServerSession(1839972036)--Connection(32490450)--Thread(Thread["http-bio-8080"-exec-3,5,main])--Connection released to connection pool [read].
2012-05-06 17:34:52,914 ["http-bio-8080"-exec-3] DEBUG org.springframework.beans.factory.annotation.InjectionMetadata - Processing injected method of bean 'org.bixin.dugsi.domain.Department': PersistenceElement for transient javax.persistence.EntityManager org.bixin.dugsi.domain.Department.entityManager
2012-05-06 17:34:52,914 ["http-bio-8080"-exec-3] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'entityManagerFactory'
[EL Finest]: query: 2012-05-06 17:34:52.915--ServerSession(1839972036)--Thread(Thread["http-bio-8080"-exec-3,5,main])--Execute query ReadObjectQuery(name="schoolDepartment" referenceClass=School )
[EL Finest]: query: 2012-05-06 17:34:52.915--ServerSession(1839972036)--Thread(Thread["http-bio-8080"-exec-3,5,main])--Execute query ReadAllQuery(name="programs" referenceClass=Program )
[EL Finest]: connection: 2012-05-06 17:34:52.916--ServerSession(1839972036)--Connection(63558014)--Thread(Thread["http-bio-8080"-exec-3,5,main])--Connection acquired from connection pool [read].
[EL Finest]: connection: 2012-05-06 17:34:52.916--ServerSession(1839972036)--Thread(Thread["http-bio-8080"-exec-3,5,main])--reconnecting to external connection pool
[EL Fine]: sql: 2012-05-06 17:34:52.917--ServerSession(1839972036)--Connection(920168739)--Thread(Thread["http-bio-8080"-exec-3,5,main])--SELECT programID, ACTIVE, CODE, DESCRIPTION, NAME, PROGRAMTYPE, REQUIREDCREDITS, version, SCHOOL_id FROM PROGRAM WHERE (SCHOOL_id = ?)

1 个答案:

答案 0 :(得分：0)

我为每个OneToMany关系添加了fetch = FetchType.Eager，因为它是Lazy Loading所有引用实体。不知道这是否是性能问题，但我想我还是需要那些列

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