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Resolved Datawindow Object tag property containing ? character ends up with double quotes

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  1. Mark Jones
    Mark Jones
  2. PowerBuilder
  3. Thursday, 16 January 2020 19:00 PM UTC

It appears that if the tag property of a datawindow object contains a ? or tab character then when you retrieve the value of the tag using dwo.tag or describe() it embeds the tag in doublequotes.

e.g.

The tag on a datawindow object is set to xxx?xxx.   

In the clicked event

string ls_tag

ls_tag=dwo.tag

messagebox("tag",ls_tag)

This will display "xxx?xxx" with double quote characters as part of the string!

Whereas if the tag on the field is xxx-xxx then this will display xxx-xxx without the extra quotes.

I have identified ? and tab characters as causing this problem.  I am sure there are other characters.  Since the tag is a simple string property there is no reason for this behavior!   

I am going to write this up as a bug unless someone can give me a good reason for this being valid.

 

Mark Jones

  1. DataWindow
  2. PowerBuilder
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Responses (2)
Mark Jones
Mark Jones Accepted Answer Pending Moderation
  1. Thursday, 16 January 2020 21:49 PM UTC
  2. PowerBuilder
  3. # 1

Thanks for your reply,  that was our thought also  -  i.e. it was related to their expression parsing and the fact they return ? for an empty/invalid expression.    I guess we will have to always strip quotes off from any a tag value that we retrieve.   If the tag is truly quoted it then looks like this "~"bla~"" so we can always safely remove outer quotes if they exist. 

Thanks,

Mark

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Michael Kramer
  1. Michael Kramer
  2. Thursday, 16 January 2020 22:45 PM UTC
Sounds like a good approach.
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Michael Kramer
Michael Kramer Accepted Answer Pending Moderation
  1. Thursday, 16 January 2020 21:38 PM UTC
  2. PowerBuilder
  3. # 2

I expect it stems from the way the DataWindow syntax is tokenized.

Result =  ?  without quotes indicates "no value detected, hence default value applies."

TAB character is separator when a property may contain an expression. Say you have Color defined as BLACK (value = 0) but also an expression making value red if it is negative. EXPRESSION = if( price < 0, 192, 0 ). That value + expression in DataWindow syntax in (e.g. Edit Source) is represented as:

column( . . . color="0~tif( price < 0, 192, 0 )" . . . )

If DW engine didn't quote such results you would have a hard time knowing what you received. Examples:

Returned by dwo.Tag Interpretation
?   <= No quotes Does Tag contain just question mark?
- or - is there no Tag value hence you must rely on default value?
~t   <= Tab character Does Tag contain the static value = TAB?
- or - Is Tag static value = empty string and the DW expression also = empty string?

That is my guess on why you see that behavior.
I still prefer the text presented same way either always with or always without quotes.
Although I accept that altering behavior if this is "legacy behavior" since early PB versions then Appeon can't strange functionality without breaking a lot of existing apps.

HTH /Michael

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