Hidden Parameters: The Key Under the Mat

Locking parameters inside of Revit content is sometimes a necessity: getting logic to work properly requires some gears to turn and parameters that hold and relay data. In very complicated families that include arrays, moving components, or even error messaging if multiple incompatible options are chosen, the amount of parameters can quickly build up. Revit has a built-in solution to hide those parameters, to keep families clean and only present information that will be important to users of the content: hidden parameters. Little known and under-utilized, hidden parameters can really clean up content when used properly. The best part is it only requires one extra step after the parameter has been made – so they’re fast, easy, efficient, and add functionality. What more can you ask for in a modelling technique? As an example I will be making a simple box with three types of different dimensions and colors, locked out, with the “key” hidden from the user.

The process of creating a hidden parameter begins like a normal shared parameter. When adding a parameter to a family, select the “Shared” option instead of family. It might make sense to create a new file specifically to hold hidden parameters, to keep them segregated from other shared parameters and to make them easy to access. There is no obvious way to tell if a shared parameter is hidden without loading it into a Revit project, so a separate hidden parameters file would make that distinction: any parameter within the file, will be hidden. No guessing or testing involved. For this example I made a new shared parameter file simply called “Hidden Parameters” and a group within the file named “Constraints”.

Hidden Parameters 1

Hidden Parameters 2

Create a new file if needed. Groups can be added to the file once it is made.

Revit Quirk Alert: An important note here before continuing is to go through the entire creation process, including the step to make the parameter hidden, before adding the shared parameter to a family. If it is added to a family before being turned into a hidden parameter it will be visible.

Add any necessary parameters to the file as they are required: there is no limit on the data type of a hidden parameter. Once any parameters have been created and added, they can be used inside of the family as normal. Since these are shared parameters, I prefer to name all of my hidden parameters with a “z” in front, such as “z Type”, “z Width”, “z Model Number”, etc. This will put them at the bottom of the parameter list inside of a project and also signifies that the parameter is hidden in the family editor.

Now for the final step (really, that’s it!): open the shared parameter file in a .txt file editor such as Notepad. The first thing you’ll see is a message to not edit the file…

Just ignore that.

You’ll then see a list of parameters as well as how they are organized inside of Revit and some data that lets Revit know how the parameter is used. Change a single value: the second integer. It will be a “1”. Change it to a “0”.


Hidden Parameters 3

Save the file and you’re done. Now that parameter is hidden in a project when added to a family.

For my example I made two hidden parameters: “z Type” and “z Material”. The visible dimensions are locked out using z Type, and the material (which can not be locked – just the nature of material parameters since they are unable to use formulas) is hidden so it cannot be modified in a project.

Hidden Parameters 4

Hidden Parameters 5

Dimensions locked and materials changed by hidden parameters. Note that there is no “Constraints” category in the Type Properties.

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