Hibernate - Custom Dialect的BigDecimal列映射 [英] Hibernate - BigDecimal column mapping for Custom Dialect

问题描述

我使用Hibernate作为我们的对象关系映射（Object-Relational Mapping），并为一个模糊的数据库提供了一个自定义的方言。

我从这个数据库中检索的实体有一个列如此：

  @Column（name =GROSS_WEIGHT，precision = 9，scale = 3）
 private BigDecimal总重量; 
  

数据库将此列定义为数字，精度为9，比例为3。 p>

我可以看到Hibernate生成的用于检索数据的SQL，当我使用数据库查询工具执行相同的查询时，它会为GROSS_WEIGHT列返回'9.68'。但是，在由Hibernate检索的实体中，'grossWeight'字段包含值'10'，其中比例 0和精度 of 2！

在我正在使用的自定义方言类中尝试过覆盖以下列类型：

  registerColumnType（Types.DECIMAL，numeric（$ p，$ s））; 
 registerColumnType（Types.DOUBLE，numeric（$ p，$ s））; 
 registerColumnType（Types.NUMERIC，numeric（$ p，$ s））; 
  

但它仍然会返回（整数）整数。

在应用程序的其他地方，我们使用Postgres方言从Postgres中检索对象。

任何想法我应该在方言中做我可以让Hibernate正确设置检索到的BigDecimal的精度/缩放比例吗？

解析方案

好的，下载完Hibernate源代码后，使用NetBeans中的调试器进行调试，发现问题出在专有JDBC驱动程序的 ResultSet 子类中，而不是在Hibernate中。

getBigDecimal 方法始终返回值为0的值。

当我联系了JDBC驱动程序的开发人员，他发现了错误并修复了它。

I'm using Hibernate as our Object-Relational Mapping, with a custom dialect for an obscure database.

The Entity I'm retrieving from this database has a column thus:

    @Column(name = "GROSS_WEIGHT", precision = 9, scale = 3)
    private BigDecimal grossWeight;

The database has this column defined as numeric with a precision of 9 and a scale of 3.

I can see the SQL that Hibernate generates to retrieve the data, and when I perform the same Query using the database query tool it returns '9.68' for the GROSS_WEIGHT column.

However, in the Entity that is retrieved by Hibernate, the 'grossWeight' field contains the value '10', with a scale of 0 and precision of 2!

in the custom dialect class I'm using I've tried overriding the following Column Types:

        registerColumnType( Types.DECIMAL, "numeric($p,$s)" );
        registerColumnType( Types.DOUBLE, "numeric($p,$s)" );
        registerColumnType( Types.NUMERIC, "numeric($p,$s)" );

but it stills returns just the (rounded) whole number.

This has worked elsewhere in the application where we retrieve objects from Postgres using the Postgres dialect.

Any idea what I should be doing in the dialect so I can get Hibernate to correctly set the precision/scale of the BigDecimal retrieved?

解决方案

OK, after downloading the Hibernate sources, and stepping thru them with the debugger in NetBeans, I discovered that the problem lay in the proprietary JDBC driver's ResultSet sub-class, not in Hibernate.

The getBigDecimal method was always returning a value with a scale of 0.

When I contacted the developer of the JDBC driver, he spotted the bug and fixed it.

这篇关于Hibernate - Custom Dialect的BigDecimal列映射的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！