Get project length unit symbol

[atis.sed]

Hi everyone,

I have cross searched the internet, this forum, Revit 2023 SDK and the  thebuildingcoder blog for a rather simple problem- how to display length symbol for documents units. How to get ForgeTypeID for active documents unit symbol?

Units docUnits = doc.GetUnits();
ForgeTypeId spec = SpecTypeId.Length;
FormatOptions myFormat = docUnits.GetFormatOptions(spec);
ForgeTypeId mySymbol = myFormat.GetSymbolTypeId();
string unitSymbol = LabelUtils.GetLabelForSymbol(mySymbol);
//Autodesk.Revit.Exceptions.ArgumentException: 'Symbol must have a definition.
Parameter name: symbolTypeId'

[aignatovich · Accepted solution]

Check

mySymbol.Empty();

If it's false before calling

LabelUtils.GetLabelForSymbol(mySymbol);

If it's true, then no symbol is specified, e.g. your unitSymbol would be an empty string

[esatis]

Is it possible to get unit Symbol for length units set in Document IF the Symbol is not set in the Document ?
For example, in my document I have millimeters set as Length, with no symbol. In Text Note Type the symbol "mm" is present, BUT it is not present when snooping object. But when I LookupParameter("Text Size")?.AsValueString()   I get 3.5000 mm. So there is some automatic formatting to Text Size parameter that takes into account "mm" Symbol even if it is not set in Document.
(image below)

Here is my method for formatting Units and I would like to be able to add Symbol to output string even if it is not set in Doc. 

public static string ConvertUnits(double value, Document doc)
        {
            
            Units docUnits = doc.GetUnits();
            ForgeTypeId spec = SpecTypeId.Length;
            FormatOptions myFormat = docUnits.GetFormatOptions(spec);
            ForgeTypeId mySymbol = myFormat.GetSymbolTypeId();
           

            string unitSymbol = "";     
            if (!mySymbol.Empty())
            {
                unitSymbol = "";
            }
            else
            {
                unitSymbol = "//SYMBOL FOR LENGTH UNITS SET IN DOCUMENT"; 
            }
            
            return _ = UnitFormatUtils.Format(docUnits, spec, value, false) + unitSymbol;
        }

[rufaidemir]

can you give an example please

[Chuong.Ho]

This is full example for get unit symbol from parameter :

private string GetSymbolUnit(Parameter parameter)
        {
            if (parameter.StorageType != StorageType.Double) return String.Empty;
            ForgeTypeId? unitTypeId = parameter?.GetUnitTypeId();
            return GetSymbolUnit(unitTypeId);
        }
        private string GetSymbolUnit(ForgeTypeId unitTypeId)
        {
            if (!FormatOptions.CanHaveSymbol(unitTypeId))
            {
                return null;
            }

            var validSymbols = FormatOptions.GetValidSymbols(unitTypeId);
            var typeId = validSymbols?.Where(x => !x.Empty());
            foreach (var symbolId in typeId!)
            {
                return LabelUtils.GetLabelForSymbol(symbolId);
            }

            return null;
        }

And example for get from formatoption without exeption

   FormatOptions formatOptions = Doc.GetUnits().GetFormatOptions(SpecTypeId.Length);
            // get symbol unit
            ForgeTypeId forgeTypeId = formatOptions.GetUnitTypeId();
            string symbol = GetSymbolUnit(forgeTypeId);