创建后的Revit API编辑元素

Question

I have a questions that is more theory of "best practices" than actual technical programming.

I am trying to think of the best way to handle editing an element after it is placed by my program. Specifically I have my program set up as follows:

User clicks a tool that essentially "adds some families into a project" in Revit. It reads a sketch created by user and places items based on the sketch.

Sketch

Element creation

I want to give the user the ability to "edit the sketch" of those elements similar to say a floor slab. I don't believe the Revit API exposes the ability to sketch using "sketch mode". I am trying to mimic this very useful capability in my program.

So, what I have done is used extensible storage and store an UniqueId into all elements created using my tool. What the program does is when the user clicks "edit elements" tool, the program asks for the new sketch, asks to click on existing element, reads the UniqueId of the existing element and calls all elements with that UniqueId and deletes them, then the program adds new elements into the project again using the users "new sketch".

The problem is, if the user deletes the original elements that were added to the project and then tries to edit them, how do I guarantee the user is not going to delete those original elements that have the UniqueId? I think the way to go is to use the Dynamic Model Update functionality in the Revit API.

How are most of these algorithms written? Am I on the right track here? Do I just assign UniqueIds to elements and store them on the elements themselves so I can call them up later? Maybe there is a basic theoretical piece of the puzzle I am missing. Data structures?

Answer 1

I think you are essentially on the right track.

Using extensible storage to store the UniqueIds is definitely the way to go, and also using the DMU dynamic model updater functionality to react to changes sounds good.

The one thing that seems to be unclear is the fact the Revit will automatically assign the unique ids to the elements when they are created, and there is nothing you can do to affect that. The unique id is unique and immutable, and you have no control over it.

Therefore, the easiest approach is probably to delete all the previous sketch elements and recreate the entire sketch and all elements defining it from scratch whenever the sketch needs to be modified in any way.

Answer 2

You should use ElementId instead of UniqueId for structured storage, because an ElementId is automatically remapped to the new ElementId when a work sharing update occurs. The ElementId is also set To ElementId.InvalidElementId when the element is deleted.