[hibernate-issues] [Hibernate-JIRA] Closed: (HHH-1127) HQL's special use of the "id" property name interferes with user Object models

[Steve Ebersole (JIRA)]

     [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-1127?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Steve Ebersole closed HHH-1127.
-------------------------------


Closing stale resolved issues

> HQL's special use of the "id" property name interferes with user Object models
> ------------------------------------------------------------------------------
>
>                 Key: HHH-1127
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-1127
>             Project: Hibernate Core
>          Issue Type: Improvement
>          Components: core
>         Environment: Hibernate HQL in all of its versions up to the recent version 3.1
>            Reporter: Gunther Schadow
>   Original Estimate: 8h
>  Remaining Estimate: 8h
>
> When a user decides to use the name "id" as the name of a property, HQL queries break with unspecific exceptions, because HQL assumes "id" as reserved for the Hibernate id attribute defined in the hbm file using the <id .../> tag. This is bad design in our view, because it puts an unnecessary constraint and interference with the otherwise transparent "object persistence for idiomatic Java."
> For example, a mapping file may contain:
> <class name="MyObject">
>   <id name="internalId" ... />
>   <property name="id" .../>
>   <property name="foo" .../>
> </class>
> now I like to make an HQL query
> from MyObject where id='123'
> and this would fail because 'id' in HQL means the 'internalId' property not the property called 'id'.
> I could hack org.hibernate.persister.entity.EntityPersister, changing line
>    public static final String ENTITY_ID = "id";
> to
>    public static final String ENTITY_ID = "hid";
> But that of course is breaking it for anyone who uses "hid" as a normal property name.
> I think the flaw here is that HQL should use the hbm metadata to take the attribute designated as by
> the class/id/@name attribute in the mapping file rather than using this static constant "id" literal.
> The following classes use the ENTITY_ID constant:
> hql/ast/tree/DotNode.java
> hql/ast/tree/FromElement.java
> hql/ast/tree/FromElementType.java
> hql/classic/PathExpressionParser.java
> persister/entity/AbstractEntityPersister.java
> persister/entity/AbstractPropertyMapping.java
> persister/entity/EntityPersister.java
> and most of the work would be in PathExpressionParser, for someone who knows this it should
> not take more than a day to fix.
> The problem is that it would break backward compatibility with existing HQL queries. But there is really no alternative than to make the change, because either you keep it a perpetual problem for new users or you make it a short term problem for old users. One might consider using some special symbol, such as "@id" to stand as an alias for the actual name of the id property. That would make conversion really easy.

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