In Active Collab 4, there is a difference between "brief" API responses (used when returning large lists of objects), and detailed responses (used when a single object is returned via API).
When you are listing a list of tasks, you will get all individual tasks in brief format, but when you fetch details of each task, you'll get a detailed response.
In brief task responses, completed_on
timestamp is not included, only whether tasks is completed or not (is_completed
). To get the timestamp of completed tasks, make an additional call to task API for each task that is completed:
https://activecollab.com/help-classic/books/api/tasks#s-task-id
PS: In Active Collab 5, we removed brief and detailed concept, so each object always returns a single set of properties.