查询@ElementCollection JPA [英] Query @ElementCollection JPA

问题描述

我有一个实体 交易如下：

  @Entity 
类Transaction延伸AbstractEntity< Long> {
 private static final long serialVersionUID = 7222139865127600245L; 
 //其他属性
 $ b $ @ElementCollection（fetch = FetchType.EAGER，targetClass = java.lang.String.class）
 @CollectionTable（name =transaction_properties，joinColumns = @JoinColumn（name =p_id））
 @MapKeyColumn（name =propertyKey）
 @Column（name =propertyValue）
私人地图< String，String>性能; 
 
 // getters and setters 
} 
  

所以，我的数据库表对于 transaction_properties 是


 的MySQL> desc transaction_properties; 
 + --------------- + -------------- + ------ + ----- +  - -------- + ------- + 
 |字段|类型|空| Key |默认|额外| 
 + --------------- + -------------- + ------ + ----- +  - -------- + ------- + 
 | p_id | bigint（20）| NO | PRI | | | 
 | propertyValue | varchar（255）|是| | NULL | | 
 | propertyKey | varchar（255）| NO | PRI | | | 
 + --------------- + -------------- + ------ + ----- +  - -------- + ------- + 
 3行（0.00秒）
  

现在，我想用键和值搜索实体 Transaction 。

 路径< Map< String，String>> propertiesPath = root.get（properties）; 
路径< String> propertyKeyPath = propertiesPath。< String>获得（ PROPERTYKEY）; //其中m出现错误
路径< String> propertyValuePath = propertyKeyPath。< String>获得（ 的PropertyValue）; 
p = cb.and（p，cb.and（cb.like（propertyKeyPath，％+ searchTrxnKey +％），cb.like（propertyValuePath，％+ searchTrxnValue +％））） ; 
  

但是出现 Path< String>错误propertyKeyPath = propertiesPath。< String> get（propertyKey）; 如下：



  [...]抛出一个意外的异常：org.springframework.dao.InvalidDataAccessApiUsageException：非法尝试取消引用路径源[null];嵌套异常是java.lang.IllegalArgumentException：非法尝试解引用路径源[null] 
  

其中之一我经历的参考是： Spring JPA教程第四部分：JPA标准查询但对我来说没有好运。 解决方案是 .join（properties） than .get（properties）。

 路径< Map< String，String>> propertiesPath = root.join（properties）; 
 predicate =（predicate！= null）？标准构建器.and（predicate，criteriaBuilder.and（propertiesPath.in（searchTrxnKey），propertiesPath.in（searchTrxnValue）））
：criteriaBuilder.and（propertiesPath.in（searchTrxnKey），propertiesPath.in（searchTrxnValue））; 
  

更多 JPA Criteria API - 如何添加JOIN子句（尽可能使用普通语句）

I have an Entity Transaction as following :

@Entity
class Transaction extends AbstractEntity<Long>{
        private static final long serialVersionUID = 7222139865127600245L;
        //other attributes

    @ElementCollection(fetch = FetchType.EAGER, targetClass = java.lang.String.class)
    @CollectionTable(name = "transaction_properties", joinColumns = @JoinColumn(name = "p_id"))
    @MapKeyColumn(name = "propertyKey")
    @Column(name = "propertyValue")
    private Map<String, String> properties;

    //getters and setters
}

So, my Database Table for transaction_properties is

mysql> desc transaction_properties;
+---------------+--------------+------+-----+---------+-------+
| Field         | Type         | Null | Key | Default | Extra |
+---------------+--------------+------+-----+---------+-------+
| p_id          | bigint(20)   | NO   | PRI |         |       |
| propertyValue | varchar(255) | YES  |     | NULL    |       |
| propertyKey   | varchar(255) | NO   | PRI |         |       |
+---------------+--------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

Now, I want to search entity Transaction with key and value.

    Path<Map<String, String>> propertiesPath = root.get("properties");
    Path<String> propertyKeyPath = propertiesPath.<String> get("propertyKey"); //where m getting error
    Path<String> propertyValuePath = propertyKeyPath.<String> get("propertyValue");
    p = cb.and(p, cb.and(cb.like(propertyKeyPath, "%" + searchTrxnKey + "%"), cb.like(propertyValuePath, "%" + searchTrxnValue + "%")));

But am getting error for Path<String> propertyKeyPath = propertiesPath.<String> get("propertyKey"); as following :

[...] threw an unexpected exception: org.springframework.dao.InvalidDataAccessApiUsageException: Illegal attempt to dereference path source [null]; nested exception is java.lang.IllegalArgumentException: Illegal attempt to dereference path source [null]

One of the reference I went through was : Spring Data JPA Tutorial Part Four: JPA Criteria Queries but no luck for me.

解决方案

The solution is .join("properties") than .get("properties").

Path<Map<String, String>> propertiesPath = root.join("properties");
predicate = (predicate != null) ? criteriaBuilder.and(predicate, criteriaBuilder.and(propertiesPath.in(searchTrxnKey), propertiesPath.in(searchTrxnValue)))
                                : criteriaBuilder.and(propertiesPath.in(searchTrxnKey), propertiesPath.in(searchTrxnValue));

More at JPA Criteria API - How to add JOIN clause (as general sentence as possible)

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