MySQL视图中的LONGTEXT字段的JPA本地查询导致错误 [英] JPA native query for LONGTEXT field in a MySQL view results in error

问题描述

我有以下JPA SqlResultSetMapping：

  @SqlResultSetMappings（{
 @SqlResultSetMapping（name =GroupParticipantDTO ，
列= {
 @ColumnResult（name =gpId），
 @ColumnResult（name =gpRole），
 // @ColumnResult（name =gpRemarks ）
} 
）
  

这样使用：

  StringBuilder sbQuery = new StringBuilder（Select）; 
 sbQuery.append（gpId，）; 
 sbQuery .append（gpRole，）; 
 // sbQuery.append（gpRemarks）; 
 
 sbQuery.append（FROM v_group_participants_with_details）; 
 
 Query query = em.createNativeQuery（sbQuery.toString（），GroupParticipantDTO）; 
  

像这样：
$ b $ pre $ code $ DROP VIEW如果存在`v_group_participants_with_details`;
CREATE VIEW`v_group_participants_wit h_details`
AS
SELECT
gp.id AS gpId，
gp.role AS gpRole，
gp.remarks AS gpRemarks
FROM GroupParticipation gp
;

GroupParticipation表的备注列定义为LONGTEXT（我正在使用Mysql 5.x）

现在解决问题：
当查询字段从查询中被注释掉时，所有的工作都完美无缺，但是如果我尝试在查询中包含备注字段，我得到以下错误：

  javax.persistence.PersistenceException：org.hibernate.MappingException：
无方言映射JDBC类型：-1 
 at org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException 
（AbstractEntityManagerImpl.java:614）
位于org.hibernate.ejb.QueryImpl.getResultList（QueryImpl.java:76 ）
  

什么给了？如何从本地查询获取LONGTEXT列？

解决方案

这个问题在 HHH-1483 和 HHH-3892 。简而言之，Hibernate不知道如何映射本地查询返回的 LONGVARCHAR 列。

这个问题在Hibernate 3.5.0+中修复。对于以前的版本，解决方法是扩展 MysqlDialect ，为<$ c $注册正确的Hibernate 类型 c> LONGVARCHAR ：

  import java.sql.Types; 
 
导入org.hibernate.Hibernate; 
 
 public class MyMySQL5Dialect extends org.hibernate.dialect.MySQL5Dialect {
 public MyMySQL5Dialect（）{
 super（）; 
 //注册额外的hibernate类型，默认用于标量sqlquery类型自动检测
 registerHibernateType（Types.LONGVARCHAR，Hibernate.TEXT.getName（））; 
} 
} 
  

I have the following JPA SqlResultSetMapping:

 @SqlResultSetMappings({               
    @SqlResultSetMapping(name="GroupParticipantDTO", 
            columns={ 
                @ColumnResult(name="gpId"),
                @ColumnResult(name="gpRole"),
 //             @ColumnResult(name="gpRemarks")
            }  
    )

Which is used like this:

    StringBuilder sbQuery = new StringBuilder("Select  ");
    sbQuery.append(" gpId, ");
    sbQuery.append(" gpRole, "); 
 // sbQuery.append(" gpRemarks ");

    sbQuery.append(" FROM v_group_participants_with_details ");

    Query query = em.createNativeQuery(sbQuery.toString(), "GroupParticipantDTO");

The view is like this:

DROP VIEW IF EXISTS `v_group_participants_with_details`;
CREATE VIEW `v_group_participants_with_details`
AS
SELECT
   gp.id AS gpId,
   gp.role AS gpRole,
   gp.remarks AS gpRemarks
FROM GroupParticipation gp
;

The GroupParticipation table has the remarks column defined as LONGTEXT (I'm using Mysql 5.x)

Now for the problem: When the remarks field is commented out from the query everything works perfectly, but if I try to include the remarks field in the query, I get the following error:

 javax.persistence.PersistenceException: org.hibernate.MappingException: 
 No Dialect mapping for JDBC type: -1   
 at org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException
 (AbstractEntityManagerImpl.java:614)   
 at org.hibernate.ejb.QueryImpl.getResultList(QueryImpl.java:76)

What gives? How can I get a LONGTEXT column from a native query?

解决方案

This problem is reported in HHH-1483 and HHH-3892. In short, Hibernate does not know, how to map a LONGVARCHAR column returned by a native query.

This problem is fixed in Hibernate 3.5.0+. For previous versions, a workaround would be to extend the MysqlDialect to register the correct Hibernate Type for a LONGVARCHAR:

import java.sql.Types;

import org.hibernate.Hibernate;

public class MyMySQL5Dialect extends org.hibernate.dialect.MySQL5Dialect {
    public MyMySQL5Dialect() {
        super();
        // register additional hibernate types for default use in scalar sqlquery type auto detection
        registerHibernateType(Types.LONGVARCHAR, Hibernate.TEXT.getName());
    }
}

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