Material.GetParameterAsString() returns null

[Anonymous]

I am porting a material takeoff application from Revit 2014 to 2016. I have managed to catch most of the API changes. Retreiving a parameter valuse from Material is one that is not working like it does in Revit 2014.

The UsageId parameter is a string storage type we used in Revit 2014. Material.GetParamaterAsString("UsageId", true) will return the value since it is a string with Revit 2014.

Using the same method with the same model with Revit 2016 returns an empty string. I am wondering if I have to use a different method to retreive a material's parameter value?

Any ideas why this is different in Revit 2016.

Larry

[jeremytammik]

Dear Larry,

Thank you for your query.

Have you tried using the much simpler and more direct access to a string value provided by the Parameter.AsString method?

As far as I can tell, you should have been using that in the first place.

I recommend always using the direct access methods AsString, AsElementId, AsDouble, AsInteger etc.

Looking at the Revit 2016 API help file RevitAPI.chm, I do not see any GetParamaterAsString at all.

Are you sure that is a standard Revit API method and not an extension method of your own?

By the way, looking at it more closely, there is a typo in the name.

Do you mean GetParameterAsString?

The Revit API does not provide such a method either, though.

I hope this helps.

Best regards,

Jeremy

[Anonymous]

Hey, 

i've just tried the following command and it worked (in Python): 

material = [a for a in familyManager.Parameters if a.Definition.Name == 'Structural Material' ][0]
materialId = familyManager.CurrentType.AsElementId( material ) 
materialValue = famDoc.GetElement( materialId ) 

print  materialValue.Name

it is probably not the cleanest code, but it get's the job done =P 

cheers~

[jeremytammik]

I am glad that you found a solution.

Yes, definitely not the cleanest or most efficient one.

For one, you could replace the first line and the iteration over all parameters by a call to LookupParameter.

Secondly, looking up a parameter by name is always a bad idea when it can be avoided.

In this case, you can easily use a built-in parameter enumeration value to retrieve the parameter directly with no iteration or name lookup at all.

Cheers,

Jeremy