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## Constraints for Length

I need to place constraints on a length of metal panel and I can not for the life of me create a parameter that will work. What I need the parameter to do is the Length of the Panel can be as long as 30'-0" and as small as 1'-6" but I can not make it so that if the panel is say fifteen that it will stay that way. What am I doing wrong? Or am I using the wrong parameters I usually use dimensions and constraints so. I think I have tried hundreds of formulas and none of them work.

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## Re: Constraints for Length

You would need to create two parameters to define a valid range for the value. One parameter would be the user-inputted value, and the other parameter would be the true value, which would have the following formula:

if(Length_UserInput > 30', 30', if(Length_UserInput < 1' 6", 1' 6", Length_UserInput ))

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## Re: Constraints for Length

the length_userinput would be a constraint or dimension?

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## Re: Constraints for Length

Nope. The sole purpose of that parameter is to allow the user to input the desired length. The second Parameter (with the formula) is tied to the contraining dimension. See attached example.

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## Re: Constraints for Length

ok. so I understand that but how do I make it so that the formula can not be changed about an outside source.
(sorry everything about that I know is self taught.)

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## Re: Constraints for Length

Originally Posted by awinkler514194
ok. so I understand that but how do I make it so that the formula can not be changed about an outside source.
Sorry, I don't exactly understand what you mean. You wish to prevent changes to the formula from an "outside source"; do you that mean you want to stop other users from being able to open the family and change the formula?

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## Re: Constraints for Length

Sorry, I don't exactly understand what you mean. You wish to prevent changes to the formula from an "outside source"; do you that mean you want to stop other users from being able to open the family and change the formula?
yes that's what I want.Thanks!

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## Re: Constraints for Length

Originally Posted by awinkler514194
yes that's what I want.Thanks!
Unfortunately, that's not possible. There is no mean of protecting a family or its contents at the moment, that I am aware of.

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## Re: Constraints for Length

You could put the formula in a nested family and name the nested family the same as the host family. A user would have to know to rename the nested family in order to get it to open in the same session of Revit as the host family. A deterrent but not a true lock.