Controlling user inputs in families

When building Revit families, and wanting to avoid nightmares, it may be useful to be in control of the user inputs. It could be a door that can´t be made if it´s more than 1200 mm´s (4´-0") wide.

Now, there´s a couple of ways to aproach this, but only one of them will actually tell the user that the input is not acceptable, I tend to combine two methods - 1. Warning & 2. Control

Warning Method

For this we need a custom parameter (yes/no) called "Width Warning", with a formula like this

not(Width < 1200 mm)

Now, create some model text, with a warning to the user - choose element properties for the model text, and aply the "Width Warning" parameter under "Graphics > Visible"

Now, if a user inputs 1200 mm´s or more as the width, the model text will show, and tell the user to correct the problem.

Control Method

It´s also possible to control the input, just in case that the user chooses to ignore the warning.

Create a new length parameter called "Controlled Width" and ad a formula like this:

if(Width > 1200 mm, 1200 mm, Width)

Now change the label for the current width dimension, to the new "Controlled Width" parameter.

Now the user get´s  a warning, and the door keeps a max. width of 1200 mm´s, even if the user input is greater than 1200 mm´s.

Download the example Door family