如何在查询中转义Hibernate关键字？

问题描述

不幸的是，我住在白俄罗斯，域名区域.BY

我正在使用Hibernate ORM和Spring Data JPA。我在，因为BY是SQL中的保留字。

  import org.springframework.data.jpa.repository.JpaRepository; 
 import org.springframework.data.jpa.repository.Query; 
 import org.springframework.data.repository.query.Param; 
 
 import java.util.List; 
 
 import by.naxa.project.model.Event; 
 import by.naxa.project.model.Demo; 
 import by.naxa.project.model.Pair; 
 import by.naxa.project.model.Response; 
 import by.naxa.project.model.User; 
 
 public interface DemoRepository扩展了JpaRepository&Demo，Long> {
 
 / ** 
 *查找给定事件的所有回复。 
 * 
 * @param事件事件。 
 * @return用户响应元组的列表。 
 * / 
 @Query（SELECT new by.naxa.project.model.Pair（demo.invitee，demo.response）FROM Demo demo WHERE demo.event =：event）
列表<配对<用户，响应>> findResponsesByEvent（@Param（event）Event event）; 
 
} 
  

我的课程是：

• public enum Response {UNDEFINED，YES，NO，MAYBE}




• public final class Pair< F，S> （的/等于-c-pair-r-in-java）




• 实体类事件，用户和演示。

部署过程失败，并显示以下日志输出：

  DEBUG main QueryTranslatorImpl：parse：265  -  parse（） -  HQL：SELECT new by.naxa.project.model.Pair（demo.invitee，demo.response）FROM by.naxa.project.model.Demo demo WHERE demo.event =：event 
 DEBUG main ErrorCounter：reportWarning：63  - 关键字'by'被解释为一个标识符，原因如下：expecting IDENT，found'by'
 DEBUG main HqlParser：weakKeywords：358  -  weakKeywords（）：new LT（1）令牌 -  [by，< 111>以前：< 108>，line = 1，col = 69，possibleID = true] 
 DEBUG main QueryTranslatorImpl：showHqlAst：283  -  --- HQL AST --- 
 ... 
导致：java.lang.ClassCastException：org.hibernate.hql.internal.ast.tree.SqlNode不能转换为org.hibernate.hql.internal.ast.tree.FromReferenceNode 
  

我确信唯一的错误是中的关键字被解释为标识符，因为如果我将软件包重命名为 com.naxa.project 它正在按预期工作。另外，构造函数名称必须是完全限定的，所以我无法写入 SELECT new Pair（demo.invitee，demo.response）... 。

我试图使用，''，`` （backticks），（）和 [] 。

• 反引号，双引号：
  
  

   org.hibernate.QueryException：unexpected char：'`'



• 单引号，方括号，括号：
  
  

   org.hibernate.hql.internal.ast.QuerySyntaxException：expecting IDENT，found'['

我该怎么办？

解决方案

根据Java 程序包命名约定

package by.naxa 可以重命名为 by_.naxa 。而且问题消失了。

但是我仍然希望在Hibernate查询中转义构造函数名称。

Unfortunatelly I live in Belarus, domain zone .BY

I'm using Hibernate ORM and Spring Data JPA. I have difficulty in creating new Object in SELECT statement, because BY is a reserved word in SQL.

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;

import java.util.List;

import by.naxa.project.model.Event;
import by.naxa.project.model.Demo;
import by.naxa.project.model.Pair;
import by.naxa.project.model.Response;
import by.naxa.project.model.User;

public interface DemoRepository extends JpaRepository<Demo, Long> {

    /**
     * Find all responses to the given event.
     *
     * @param event Event.
     * @return The list of User-Response tuples.
     */
    @Query("SELECT new by.naxa.project.model.Pair(demo.invitee, demo.response) FROM Demo demo WHERE demo.event = :event")
    List<Pair<User, Response>> findResponsesByEvent(@Param("event") Event event);

}

My classes here are:

• public enum Response { UNDEFINED, YES, NO, MAYBE }

• public final class Pair<F, S> (equivalent of the C++ Pair<L,R>)

• entity classes Event, User, and Demo.

Deploy process fails with the following log output:

DEBUG main QueryTranslatorImpl:parse:265 - parse() - HQL: SELECT new by.naxa.project.model.Pair(demo.invitee, demo.response) FROM by.naxa.project.model.Demo demo WHERE demo.event = :event
DEBUG main ErrorCounter:reportWarning:63 - Keyword  'by' is being interpreted as an identifier due to: expecting IDENT, found 'by'
DEBUG main HqlParser:weakKeywords:358 - weakKeywords() : new LT(1) token - ["by",<111> previously: <108>,line=1,col=69,possibleID=true]
DEBUG main QueryTranslatorImpl:showHqlAst:283 - --- HQL AST ---
...
Caused by: java.lang.ClassCastException: org.hibernate.hql.internal.ast.tree.SqlNode cannot be cast to org.hibernate.hql.internal.ast.tree.FromReferenceNode

I am sure that the only error is that the keyword by is being interpreted as an identifier, because if I rename package to com.naxa.project it is working as intended. Also constructor name must be fully qualified, so I can't write SELECT new Pair(demo.invitee, demo.response) ....

I tried to escape the constructor name with "", '', `` (backticks), () and [].

• backticks, double quotes:

  org.hibernate.QueryException: unexpected char: '`'

• single quotes, square brackets, parentheses:

  org.hibernate.hql.internal.ast.QuerySyntaxException: expecting IDENT, found '['

What should I do?

解决方案

According to Java Package Naming Conventions

package by.naxa can be renamed to by_.naxa. And the problem vanishes.

But still I'm looking for the way to escape constructor name in a Hibernate query.

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