[hibernate-issues] [Hibernate-JIRA] Commented: (HBX-716) Trick to help maintenance of HQL query.

[Max Rydahl Andersen (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HBX-716?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_28530 ] 

Max Rydahl Andersen commented on HBX-716:
-----------------------------------------

sorry for the late answer; but yes this needs to be a seperate exporter/set of templates that generates a interface that you can use in your code to get better HQL typesafety.

If your classes needs to implement this interface they can do so by adding <meta attribute="interface">IApplicationProperties</meta> assuming you configured the template to generate via the pattern "I${class-name}Properties"

> Trick to help maintenance of HQL query.
> ---------------------------------------
>
>                 Key: HBX-716
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HBX-716
>             Project: Hibernate Tools
>          Issue Type: Patch
>          Components: hbm2java
>    Affects Versions: 3.2beta6
>            Reporter: Francois Jean
>            Priority: Minor
>         Attachments: patch.txt
>
>
> I'm just sending a modification I made to a FreeMarket template in Hibernate Tools (hbm2java) to help us maintaining our HQL.
> We are using a large database with more the 300 tables and we often do a reverse-engineering of the database to keep our Java entities in synch and sometimes we have to deal with column names change. After the reverse-engineering process, the compiler will show errors for all the getter/setter that have change name. But it will not show any errors in HQL using "old" attribute names.
> For example if we have a table "Application" with a column "Version_num", we would get a Class "Application" with an attribute "versionNum" and its own getter and setter. If the column "Version_num" change its name for "App_version_num", the new attribute name will be "appVersionNum" with its new getter/setter. And the compiler will show errors for old code using the getter "getVersionNum". But will not show any errors for HQL like: "from " +Application.class.getName() + " where versionNum = 3"
> Solution:
> We modify the generation of the entity to include a constant string for each attribute name, by using these constants the compiler can flag error in HQL. The new HQL would be:
> "from " +Application.class.getName() + " where "+ Application.VERSIONNUM + " = 3"
> For now, we always generate these constants but it could be possible to trigger the constants generation by using a parameter in the ant task when asking Hibernate Tools to generate Java entities.
> Template that was modified: PojoFields.ftl
>     // Fields name constant
>     
> <#foreach field in pojo.getAllPropertiesIterator()><#if pojo.getMetaAttribAsBool(field, "gen-property", true)>
>      public static final String ${field.name?upper_case} = "${field.name}";
> </#if>
> </#foreach>
>     
>     // Fields    
> <#foreach field in pojo.getAllPropertiesIterator()><#if pojo.getMetaAttribAsBool(field, "gen-property", true)> <#if pojo.hasMetaAttribute(field, "field-description")>    /**
>      ${pojo.getFieldJavaDoc(field, 0)}
>      */
>  </#if>    ${pojo.getFieldModifiers(field)} ${pojo.getJavaTypeName(field, jdk5)} ${field.name}<#if pojo.hasFieldInitializor(field, jdk5)> = ${pojo.getFieldInitialization(field, jdk5)}</#if>;
> </#if>
> </#foreach>
> PS: This solution is not perfect, a better approach would be something that would also validate at compilation time the type of association. For example, the association "person.address.city" present in a HQL statement will only be validated when this HQL will be executed.
> François J.

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