I'm using Liferay 6.2.
My need is to add one user in LR, with a specific userID. Or alternately, update a userID with another value. The standard addUser service does not provide the possibility to specify the userID, and even the updateUser.
I would like to understand how LR choose the IDs for a new user, and if I can modify it.
thanks!
Like in almost any database driven application they're assigned in sequence. And no, you don't have to choose anything, it'll be taken care of by the framework. It needs to be unique, you can't add another user with the same ID and you must be sure that the user with this id will never be created in future. Thus: If you'd use an id that has already been given out, you'd have a duplicate. If you'd use one that has not yet been given out, you'll have a duplicate some time in future, when the sequence of ids comes to this value and the framework assigns the same id for the second time.
If you have an architecture that relies on a specific ID, your architecture is wrong. Rethink the problem and change the architecture and whatever you've already done to implement it.
LR core services use a CounterService to automatically assign UserId (and plugin developer should do the same)... so all the generating code is properly wrapper in the service methods that creates a number of rows in different tables when creating a user.
I agree with previous comment "If you have an architecture that relies on a specific ID, your architecture is wrong"... by the way you can use a tip. Do you know Expando in LR? In enables you to add virtual columns on a DB entity... by using it, you can create a virtual column "myExternalId" to table "User_" (entity "User") and store there the ID you need. Then modify your code to use the field myExternalId instead userId.
