Parameter of Revit API – 19: Add FamilyParameter (FamilyManager.AddParameter)

New family parameters (FamilyParameter) can be added to a family document through the FamilyManager.AddParameter() method. It has three different signatures and the most popular one accepts parameters of the parameter name, parameter group (BuiltInParameterGroup), parameter type ParameterType ()  and a flag to indicate if the FamilyParameter applies to instance or type.

The FamilyParameter can also be associated with a Dimension through its Label property when necessary.

The following method can create a FamilyParameter, set its value, and associate it with a Dimension:

public static void RawAddFamilyParamterAndSetValue(Dimension dim, FamilyManager famMan, FamilyType ft,
            string name, BuiltInParameterGroup group, ParameterType type, bool isInstance, object value)
        {
            FamilyParameter fp = famMan.AddParameter(name, group, type, isInstance);
            if( value!= null ) RawSetFamilyParameterValue(famMan, ft, fp, value);
            //if (value != null) fp.SetValue(famMan, ft, value);
            if( dim != null )   dim.Label = fp;
        }

        public static void RawSetFamilyParameterValue(FamilyManager fm, FamilyType ft, FamilyParameter fp, object value)
        {
            FamilyType curFamType = fm.CurrentType;
            fm.CurrentType = ft;

            try
            {
                switch (fp.StorageType)
                {
                    case StorageType.None:
                        break;
                    case StorageType.Double:
                        if (value.GetType().Equals(typeof(string)))
                        {
                            fm.Set(fp, double.Parse(value as string));
                        }
                        else
                        {
                            fm.Set(fp, Convert.ToDouble(value));
                        }
                        break;
                    case StorageType.Integer:
                        if (value.GetType().Equals(typeof(string)))
                        {
                            fm.Set(fp, int.Parse(value as string));
                        }
                        else
                        {
                            fm.Set(fp, Convert.ToInt32(value));
                        }
                        break;
                    case StorageType.ElementId:
                        if (value.GetType().Equals(typeof(ElementId)))
                        {
                            fm.Set(fp, value as ElementId);
                        }
                        else if (value.GetType().Equals(typeof(string)))
                        {
                            fm.Set(fp, new ElementId(int.Parse(value as string)));
                        }
                        else
                        {
                            fm.Set(fp, new ElementId(Convert.ToInt32(value)));
                        }
                        break;
                    case StorageType.String:
                        fm.Set(fp, value.ToString());
                        break;
                }
            }
            catch
            {
                throw new Exception("Invalid Value Input!");
            }
            finally
            {
                fm.CurrentType = curFamType;
            }
        }

The help method RawSetFamilyParameterValue() has been introduced before. The FamilyParameter Writer can generate it in no time. If necessary the extension method can be generated as well and be used in the method RawAddFamilyParamterAndSetValue() instead.

FamilyParameter Creator of RevitAddinWizardcan take care of all these.