hibernate tools and the destination package

I've had alot of challenges getting hibernate tools to generate my pojos in 2 separate processing steps. Some teams may generate the POJOS directly with annotations using hibernate tools but I have found that to allow me to make modifications to the POJOs and control various aspects of pojo generation that is not currently supported by the tools or requires changing the template (which is not hard to do) is difficult. For example, if you generate a pojo directly from the JDBC configuration, then you cannot specify an "extends" class unless you change the template.

I have found that generating the pojo through a two-step process gives me the control I need without resorting to changing the template. Here is the process I used.


  • Step 1: Create a reveng.xml file for the application. Use this reveng.xml file for Step 2.

  • Step 2: Create HBM files using a dedicated hibernate console and a dedicated code generation configuration. Use the reveng.xml file from Step 1.

  • Step 3: Modify the HBM files as appropriate. For example, adding a meta tag to indicate the superclass of my entity. If I generate the HBM files again they will be overwritten and your changes lost unless you use Eclipse's local history mechanism to merge the previous version into the new version or use version control systems. Note that I generally create POJOs without annotations as it allows me to touch only the XML files and make other changes that I find easier in the HBM files. This is a specific choice I made for my application.

  • Step 4: Generate the POJO using a dedicated hibernate console and a dedicated code generation configuration. The hibernate console for this step should have "reverse from JDBC connection" turned off and mappings specified in the configuration. The mappings should be those created in Step 2. In this case, since no reverse engineering is going on and the HBM files are the only source of information for the domain objects, hibernate tools will generate POJOs from the HBM files.



I often have problems generating the properly class and output destination combination for my POJOs. You have a few choices for specifying the package and the output destination. Generally, I modify the HBM files with a package specification as an attribute in the hibernate-mapping xml tag. Using this, the HBM will generate a POJO with the proper package specification. When doing it this way, you need to specify the top of the source directory as the output as in eclipse, the pojo java source file will then be inserted in the proper file hierarchy based on the package name.

One other way that I have not tested fully is to specify a fully qualified class name in the reverse engineering XML specification. This will create the class name with the right package and when generating the HBM file, it will be placed in the package as specified in the reveng specification. When doing this, it looks like the package specification in the reverse JDBC connection portion of the code generation configuration is ignored. Specifying the FQN in the reveng file seems to be the most direct way to have the package carry through and generate pojos directly. However, it may not be the most flexible for your build scenario.

I have never had the package specification honored in way that I could recognize for generating either pojos or hbm files when using reverse engineering from the JDBC connection for code generation.

Since HBM files are xml files, one could conceivable use an Ant talk to modify the HBM XML to automatically change the package or add other clever meta tags. I'll investigate this approach later.

Comments

Post a Comment

Popular posts from this blog

quick note on scala.js, react hooks, monix, auth

quick note on scala.js, react hooks, monix, auth Reactjs hooks finally came out of preview in a recent version of React. scalajs-reaction has had support for hooks since they were in preview. React hooks seem like the hot new thing but for me the question is, do hooks help improve your code by improving maintainability, time to market, TCO, etc.? Let’s take a look using authentication as an example and employ monix , a reactive observable framework that also builds on cats . We will assume we are building a SPA. Does it improve your code and make your application & development experience better? Auth Auth processing can be complex. Many react auth examples you find in blogs like to show how to use “react-routing” and “auth” as a switch that determines which routes are protected or unprotected. Protected routes show application specific data. Unprotected routes show login content . Based on storing a “User” object in the browser session/local storage, th...
Read more

zio environment and modules pattern: zio, scala.js, react, query management

zio environment and modules pattern: zio, scala.js, react, query management This blog covers a zio-based fetch design for scala.js, react web applications. It heavily uses the zio “environment” feature to help motivate a point of view on the modules pattern in effect systems. At the end, I summarize some thoughts on ergonomics and complexity. This blog assumes a basic knowledge of zio and react. scala.js is just like scala so you mostly already know scala.js. This blog is a follow-on to previous blogs: https://appddeevvmeanderings.blogspot.com/2019/10/scalajs-react-fetcher-hook_48.html and https://appddeevvmeanderings.blogspot.com/2019/11/scalajs-and-react-suspense.html . I have been keeping an eye on and culling ideas from typscript/javascript fetching libraries that address query management concerns. The formulation below incorporates some of those concerns but does not try to comprehensively duplicate well established javascript libraries. I only care about ...
Read more

attributes with react and typescript.md

If you use typescript with react you may wonder what the right signature is for your “properties” interface. Obviously, your component will have few to many specific properties that reflect your domain. However, you may wish to also provide for the ability to add other attributes, such as those valid for a div property. In other words, you want to extend your props interface with that of the properties from a div element. How do you do that? There are really two issues: How do you extend your props interfaces How do you filter the props once you receive them to just those that apply. Extend Your Prop Interface or Use Sum Types It’s not uncommon to see interface Props { className ? : string yourProp ? : number } with the idea of using it in class MyComponent extends React.Component<Props, any> somewhere. If your component will have an outer div, you may also pass in a react element so that its configurable. But let’s say your outer element is a div and you wan...
Read more