Currency Input

Sometime you can’t found the solution to a basic problem.

How can I use DesktopTextField to let let user input a currency value in his locale format. I lost myself with validation mask, DesktopTextField.Format, DesktopTextField.Textchanged…

Do you have a basic sample code ?
Please help!

it need try catch!

1 Like

My question is not about Currency type but about DesktopTextField control. How to configure it to help user type a currency value in is locale
Ex: “$1,200.00” or “1 200,00€”

How to allow only numerics, max two decimal digits and a currency sign according to user locale ?

It’s tricky…

My approach: no currency symbols in the field, just numbers and decimal and thousands separators. With the help of the “KeyDown” event, all other inputs are filtered out directly when typing. I have a method called FilterKeys, which checks if the pressed key is allowed and then returns “False” (Key is allowed) else “True” (Key is ignored). Have a look at the documentation for DesktopTextField.KeyDown Event. Keys are filtered with

If Keyboard.AsyncKeyDown(&h1D) Then Return False // number 0

Finally, at the “FocusLost” Event, formatting the content with Format().

There may be better ways to do this…

somehow i would give the user the freedom of input and
show the input value as real value.
the input mask in xojo i not like.

Sub TextChanged() Handles TextChanged
  Var v As Currency = 0
  #Pragma BreakOnExceptions False
    v = Currency.FromString(Me.Text,Locale.Current)
    v = Round(v*100)/100.0
  Catch e As RuntimeException
  End Try
  Label1.Text = v.ToString(Locale.Current) 
  System.DebugLog v.ToString()
End Sub

maybe create a container control for this value input to switch between input and display.

This the solution I choose. Thanks @MarkusR and other members for their help. Fell free to comment or adjust my code.

For my DesktopTextField I had this event handlers

Sub FocusLost()

Var c As Currency = 0

// Try to convert as a Locale Currency
#Pragma BreakOnExceptions False
  c = Currency.FromString(Me.Text,Locale.Current)
Catch e As RuntimeException
End Try

Me.Text = c.ToString(Locale.Current)

End Sub

And for key down management

Function KeyDown(key As String) As Boolean

Var re As New RegEx
Var match As RegExMatch

re.SearchPattern = "[a-z]"
match = re.Search(key)

If match = Nil Then Return False Else Return True

End Function

I think the regex can be more efficient but regex is a kind of black magic

I like the regex idea, but I would suggest that you list the things to allow instead of those that you don’t. You’ll need to create a dynamic constant for currency symbols and whether the language allows spaces probably but then the pattern could be:

re.searchpattern = "[0-9.," + kLanguageSymbols + "]"


US English = "$"
UK English = "£"
French = "€ "

Thank you @Greg_O but with my approach RegEx is more complex because I want keydown return false if user press an alphanumeric key. I want to allow ESC, TAB, ENTER keys…

My search pattern contains characters I don’t want not authorised characters