Question How to specify validation expression for a dynamically created widget?

[Dragon13]

Hello everyone,

I am using Progress 10.2.B07 on Windows 7, 64-bit. For CHUI I try to write a simple program, which creates a Frame and a "FILL-IN" widget in it. Now, I stuck with specification of Validation Expression for the dynamic widget. Here is my code:

def var hf as handle no-undo.
def var ht as handle no-undo.
def var hfn as handle no-undo.

create frame hf
assign
  box = yes
  row = 1
  col = 1
  width-chars = 50
  height-chars = 20
  name = "hello"
  title = "test validation"
  dcolor = 0.

create text ht
assign
  frame = hf
  row = 2
  col = 1.

create fill-in hfn
assign
  frame = hf
  row = 2
  col = 10
  width-chars = 20
  format = "x(10)"
  side-label-handle = ht
  label = "test"
  screen-value = ""
  validate-expression = "self:screen-value = hello"
  help = "say hello"
  sensitive = true.

on go of hf
  do:
  if not hf:validate("ENABLED-FIELDS") then
  return no-apply.
end.

hf:visible = true.
wait-for go of hf.

When I run it, I get message with the error code 4052. The description to this error code says quite clear that I am not allowed to set validate-Expression attribuite, but what else can I use to specify Validation for dynamically created "FILL-IN" widget???

Thank you in advance!

 

[TomBascom]

"Validation" is one of those concepts that "made a good demo" in 1985.

It has no place in a modern application.

My advice is that you not try to use it and be thankful that your attempts have not succeeded.

 

[Dragon13]

Hello Tom, thank you for the quick answer, but could explain shortly, why "It has no place in a modern application" or tell me where I could read about it? It is just, the way I see it, I have a field, where a user should type in some Information and it seems for me Logical that the entered Information should be validated.

 

[TomBascom]

Validation of this sort tightly couples logic, data and UI.

That makes a nice demo but it is a nightmare to maintain in a real application.

 

[Dragon13]

Ok, now I see what you mean. You are right, thanks for your advice. I solved it differently - without Validation.