Combining 2 family length parameters and return as text

[clog boy]

Hi, I'm new to the Revit api but have some (very little) experience with writing macros. Maybe a similar question has been asked before, in this case feel free to point me to the right direction. However I searched the internet and came up emptyhanded.
Right now I'm creating rectangular duct fittings, and the client wants to read the duct size(s) in a standardized paremeter. The default Revit 'size' parameter in the project is not suitable, it really needs to be a shared family parameter. The output format is basically "largets_duct_size x smallest_duct_size".
What would be a good way to fetch the duct size and return that as a string? Is it possible at all to dynamically fetch and throw between the family and the macro whenever the duct size changes?


Thanks in advance, B. Weinreder

[Maxence DELANNOY]

You can use DMU (Dynamic Model Updater) to track the changes and update your shared parameter: http://adndevblog.typepad.com/aec/20...arameters.html

[clog boy]

Am I right that this should be executed manually in the project? What I would prefer is an automatic update in the family itself. As I was made to understand, the Family api is slightly different from the Revit api that's used to create new features and add-ins etc.
What's typical about duct fittings is that for every change, Revit will re-generate the fitting, using the first in line with its default values, that can then be changed for a compatible fitting, and then finetuned using it's own family parameters. But the bottom line is that a duct fitting will be re-created when you modify the ducts. This event of creation should trigger a routine that reads the duct sizes through the connector, and generates a string that should be placed in the formula field of a tekst parameter.

So this event of creation should trigger:
-read instance parameters that are related to the connector size and convert to integer
-sort descending
-place in string
-put string in the formula field of the appropriate parameter

This should be easy, right? /underestimation

[TroyGates]

The API doesn't have event triggers for object modification. But you could have code run on save/sync, print, or open/close events that will update the parameters. I have something similar that updates parameters for mechanical equipment tags. It runs every time the model is saved or printed.