![]() ![]() In this article, we will learn how to create Java model classes that map to the tables in the database using Hibernate and JPA application programming interfaces. For a head start check it out here: Creating a Database Using MYSQL Command-Line Client. This article is a continuation of the previous article in which we made a database from scratch using MySQL command-line client. I found it very hard to find a blog/article that explains how to map composite primary keys, it isn’t that difficult after all, so I probably used the wrong keywords.This article is a continuation of Creating a Database Using MySQL Command-Line Client. It’s a pity that there is a bug in Hibernate Annotations, but on the other hand it’s the first real bug I found. It’s very educational to write JPA-annotations yourself, but when you’re stuck don’t try for too long, let a generator do the work for you and try to figure out why a piece of code is generated. And again a confirmation my theory: blaming a bug is just a sign of a bad developer □ Pen for so long is because there is a better solution I guess. This is almost the same as the previous example, but with an reason why the bu Private String = "SSN_ID", nullable = false, length = 10) Import = "CCSI", name = "CC_REGISTRATIONS") The only differences are an extra annotation on the class definition: and two annotations (on attId and ssnId) instead of one. The CcRegistrationsEntity is just like your normal entity. The result of the generating process was two classes (yes, I also expected one): CcRegistrationsEntity and CcRegistrationsEntityPK. This way you don’t have to scroll through pages of code and it’s easier for me to see a solution. To create a solution I just created mappings for the primary key columns (att_id and ssn_id) and a random normal column (status). The table in the way was the CC_REGISTRATIONS table. After that I can probably remove some annotations and attributes on existing annotations. My idea was to create a mapping for the annoying table and see what was generated. I remembered I wrote a blog about generating annotated classes for JPA. To clean off rust you can use Cola, so I opened a can, drank it and I almost immediately had a result. I guess I’m also a bit rusty with Hibernate. That link got me confused and it isn’t really clear what you have to do. I usually avoid those tables, but now I had no control over the tables (well actually I have, but that’s considered cheating the assignment □ )Īfter searching on google and dzone I didn’t get any further, the closest thing to a solution was a piece of information in the Hibernate manual. I forgot that some tools exist to generate the mapping, so I did it by hand.Īfter some simple tables a table with a composite Id was in my way. I used all the standard JPA annotations, so this should also work with Toplink Essentials or any other JPA-implementation. The next step was connecting to the database with Hibernate Annotations. I generated some Java classes based on the WSDL with XFire, that went quite smooth (thanks to earlier experience with XFire :). When I came home after the training I thought why not also do it in java, just to refresh my knowledge. and me) decided to make a ‘something’ with BPEL and PL/SQL. We had to create something with the SOA Suite based on the WSDL and the instructors would connect to our service to test whether we succeeded. The instructors gave us a WSDL, a database and some instructions. On the AMIS SOA training program we got a nice assignment. In this article I will explain how to map a composite primary key with JPA-annotations and how to work around the bug in Hibernate Annotations. ![]() When you’re using Hibernate Annotations you might also run into an annoying bug. A table without single-column primary key, Java developers don’t like them because it’s more work than just putting on a field. ![]()
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