Liferay Service Builder - is there a recommended way to describe a self reference relation in service.xml?

Question

I want to describe a self reference relation in a Liferay entity. Is there a recommended way to do this ?

I want to do this in order to describe a hierarchy.

At the moment, I just added a new column which I called "parentId" and I will save there the ID of the row that will be the parent of this one. If I use the "Diagram view", from within eclipse, if I draw a self reference relationship it adds a new row that duplicated the name of the ID: for example, suppose I want to describe an employee hierarchy - I have an Employee entity on which I add the default fields; one of these fields is the employeeId field which will be also the primary key. Now, if I draw a self reference relationship, the IDE will add another field entry that will be named the same way (eg. employeeId)

Answer 1

There is no official recommended way to do it, as you will have to add your own logic in your code to handle it.

In case you want to follow the convention used in Liferay code, Liferay code usually represents the hierarchy using a column called parent<primaryKey> and sometimes an auxiliary column called treePath to store the hierarchy path of the element, see:

• https://github.com/search?q=repo%3Aliferay%2Fliferay-portal+filename%3Aservice.xml+parent&type=Code
• https://github.com/search?q=repo%3Aliferay%2Fliferay-portal+filename%3Aservice.xml+treePath&type=Code

About the treePath column, service builder will add to the java class some methods (buildTreePath and updateTreePath) that will help to populate it, see the service builder templates: https://github.com/liferay/liferay-portal/blob/11e6081f96abb6bf299369519434c1eafa0658e3/modules/util/portal-tools-service-builder/src/main/resources/com/liferay/portal/tools/service/builder/dependencies/extended_model_base_impl.ftl#L65-L115

This column makes easier to get all the parent elements of the hierarchy, just split it by the / char and you will get all the primary keys of the ancestors.