Spring jpa criteriaBuilder在列表中搜索

问题描述

  @Entity 
 @Table（name = book）
 public class Book扩展内容{
 
 @ManyToMany（fetch = FetchType.LAZY）
 private List< Author>作者; 
 ...} 
  

现在，这是我的 BookSpecifications class：

  public static Specification< Book> authorIdIs（Long authorId）{
 return new Specification< Book>（）{
 @Override 
 public Predicate toPredicate（Root< Book> root，CriteriaQuery<> criteriaQuery，CriteriaBuilder cb）{ 
 return cb.isTrue（root.get（authors）。get（id）。in（authorId））; 
} 
}; 
} 
  

如何检查给定的 authorId


Error：

  java .lang.IllegalStateException：非法尝试在org.hibernate.jpa.criteria.path.Abs​​tractPathImpl.illegalDereference（AbstractPathImpl.java:98）〜[hibernate-entitymanager- 4.3.11.Final.jar：4.3.11.Final] 
在org.hibernate.jpa.criteria.path.Abs​​tractPathImpl.get（AbstractPathImpl.java：191）〜[hibernate-entitymanager-4.3.11.Final .jar：4.3.11.Final] 
 at com.tarameshgroup.derakht.service.specs.BookSpecifications $ 3.toPredicate（BookSpecifications.java:40）〜[classes /：na] 
 at org.springframework .data.jpa.domain.Specifications $ ComposedSpecification.toPredicate（Specifications.java:189）〜[spring-data-jpa-1.9.2.RELEASE.jar：na] 
  pre 
 
解决方案
为此，您可以使用Join with谓词：
 
 
请参阅贝洛w代码，
 
 
  public static Specification< Book> authorIdIs（Long authorId）{
 return new Specification< Book>（）{
 @Override 
 public Predicate toPredicate（Root< Book> root，CriteriaQuery<> criteriaQuery，CriteriaBuilder cb）{ 
 Join join = root.join（authors）; 
 return cb.equal（join.get（id），authorId）; 
} 
}; 
} 
  
 
I have a book class with a list of authors:
@Entity
@Table(name = "book")
public class Book extends Content {

    @ManyToMany(fetch = FetchType.LAZY)
    private List<Author> authors;
...}
Now, this is my BookSpecifications class:
public static Specification<Book> authorIdIs(Long authorId) {
    return new Specification<Book>() {
        @Override
        public Predicate toPredicate(Root<Book> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder cb) {
            return cb.isTrue(root.get("authors").get("id").in(authorId));
        }
    };
}
How can check the given authorId is in the list?
Error:
java.lang.IllegalStateException: Illegal attempt to dereference path source [null.authors] of basic type
    at org.hibernate.jpa.criteria.path.AbstractPathImpl.illegalDereference(AbstractPathImpl.java:98) ~[hibernate-entitymanager-4.3.11.Final.jar:4.3.11.Final]
    at org.hibernate.jpa.criteria.path.AbstractPathImpl.get(AbstractPathImpl.java:191) ~[hibernate-entitymanager-4.3.11.Final.jar:4.3.11.Final]
    at com.tarameshgroup.derakht.service.specs.BookSpecifications$3.toPredicate(BookSpecifications.java:40) ~[classes/:na]
    at org.springframework.data.jpa.domain.Specifications$ComposedSpecification.toPredicate(Specifications.java:189) ~[spring-data-jpa-1.9.2.RELEASE.jar:na]
 解决方案 
For that you can use Join with predicate:
Refer below code,
public static Specification<Book> authorIdIs(Long authorId) {
    return new Specification<Book>() {
        @Override
        public Predicate toPredicate(Root<Book> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder cb) {
                Join join = root.join("authors");
                return cb.equal(join.get("id"),authorId);
        }
    };
}
                        
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