Update item's property in a versioned repository in code

I'm kinda new in the Oracle Commerce ATG technology and don't understand many of its concepts yet. By now I have encountered an issue I couldn't find any resolution to. I'm trying to update a particular property of an item in a versioned repository using the standard way through the method setPropertyValue() on a MutableRepositoryItem object and then updateItem() on the repository object itself. But it doesn't work and I get that error message. Error message

Maybe someone could enlighten me what should I do to resolve that issue?

Solution

The process for updating a versioned and a non-versioned repository is different.

1. Non-Versioned Repository: This is pretty much easy, as you can simply get a repository item, change properties using setPropertyValue() method. Update the item and you're done. For more details, you can refer HERE: http://learnoracleatg.blogspot.in/2015/04/art212-how-to-query-atg-repository-from.html

2. Versioned Repository: The concept of updating a versioned repository is a bit tricky and very much different from a non-versioned repository. Since Versioned repositories are meant to be updated from BCC, ATG handles pretty much everything itself when using BCC. However, when you are doing things programatically, there are some things which you have to take care:-

Create a User/Persona
Create a Project
Create corresponding process using a workflow
Use a development line
Import the assets [Or use repository statements like you did for a non-versioned repository]
Advance the workflow.