Custom added parameter displaying as '?' in tag.

[nhNRTW6]

I have added a parameter to revit '24 using the API with the following code:
List<JFGParameter> sharedParameters = new List<JFGParameter>();
sharedParameters.Add(new JFGParameter() { Name = "JFG_ElementId", Group = GroupTypeId.IdentityData, DataType = SpecTypeId.String.Text });

A value is assigned to the parameter via code and, as far a I can tell, that part is working properly

I am trying to have a tag read this parameter so we can add unique identifiers to our detail drawings.

Here are pictures of the edit label screen from the tag family

Displayed tag when used on element containing a value for the parameter

I'm not sure if my problem is in the way I am adding the parameter or assigning a value. Any help would be appreciated.

[jeremy_tammik]

Afaik, there are quite a few situations and issues related with Revit displaying a question mark for a tag value:

• https://duckduckgo.com/?q=revit+tag+question+mark

Hard to tell off-hand whether the behaviour you observe is caused by your approach or some other factor... Maybe some of those discussions will help clarify?

[nhNRTW6]

Reading those forum posts I was able to pinpoint, I think, what is going wrong. It seems that the way I am adding parameters is not adding them to the shared parameters file as I cannot find the added parameters when I search for them in the dialog. The parameters are showing up in the element properties sidebar in the locations intended. I have included my code for adding the parameter in an attachment.

[nhNRTW6 · Accepted solution]

Upon a good bit of further investigation, the method I was using to add the parameters was adding them to a shared parameter group incorrectly. The original code was as folows:

hangerParameters.Add(new JFGParameter() { Name = "JFG_Rod1Diameter", Group = GroupTypeId.Construction, DataType = SpecTypeId.String.Text });

and to access the group in the file I was using this code:

JFGgroup = definitionFile.Groups.Create(parameter.Group.ToString());

This caused all parameters to be added under a group named "Autodesk.Revit.DB.ForgeTypeID" which is why the tags were displaying question marks.

As a workaround I added a string representing the group name:

hangerParameters.Add(new JFGParameter() { Name = "JFG_Rod1Diameter", Group = GroupTypeId.Construction, GroupString = "Construction", DataType = SpecTypeId.String.Text });

and changed the creation code to:

JFGgroup = definitionFile.Groups.Create(parameter.GroupString);

This code is working and is adding the parameters to the intended groups in the shared parameter file.

[jeremy_tammik]

Congratulations to solving this and thank you for the explanation.