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How to recognize specific characters in the text string?

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Posted on by Community Power Pla... Microsoft Employee

Hello all,

I would like to check whether user has entered any invalid characters and if they did show them a warning or block some buttons.

To do this, I am trying to write the code shown below, but realized that using "||" to recognize characters does not work.

Coalesce(Parent.Error, If( "*" || """" || "?"
in txt_Field.Text,
 "Please do not include any of these characters: "& Char(34)& " * : < > ? / \ |"))

That formula only respond to symbol "?", but not "*", or """". Could someone please advice how to fix it, so that several characters would be recognized?

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WarrenBelz 154,793 Most Valuable Professional on at

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Hi @Anonymous ,

Put this on the OnChange of the Text Box

With( { wSymbol: Table( {Value: "*"}, {Value: ":"}, {Value: "<"}, {Value: ">"}, {Value: "?"}, {Value: "/"}, {Value: "\"}, {Value: "|"} ) }, ForAll( wSymbol, If( Value in Self.Text, Notify( "Please type text only here", Error ); Reset(Self) ) ) )

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RusselThomas 4,014 on at

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Hi @Anonymous ,
The problem lies in the construct of your conditions - you can't string conditions by just stating the result of a condition.
For example;
If(firstName = "Bob" || "Sue" || "Frank")
won't work, but
If(firstname="Bob" || firstname="Sue" || firstname="Frank")
will work.
Try this;

Coalesce(Parent.Error, If( "*" in DataCardValue4.Text || "?" in DataCardValue4.Text || """" in DataCardValue4.Text, "Please do not include any of these characters: "& Char(34)& " * : < > ? / \ |"))

If you're feeling adventurous, you can also use Match() or MatchAll() with a regex pattern to pick up special characters.

Hope this helps,

RT

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Community Power Pla... Microsoft Employee on at

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Thank you! Appreciate the explanation!

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WarrenBelz 154,793 Most Valuable Professional on at

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Hi @Anonymous ,

Your post got me thinking there is a smarter way of doing this and it was something I might use myself, so I came up with this working model.

Firstly do a Collection of all special characters (you can do this at Screen OnVisible) by using their ASCII value ranges

ClearCollect( colChar, ForAll( Sequence(15), {FieldNo: Char(32 + Value)} ), ForAll( Sequence(7), {FieldNo: Char(57 + Value)} ), ForAll( Sequence(5), {FieldNo: Char(90 + Value)} ), ForAll( Sequence(4), {FieldNo: Char(122 + Value)} ) )

this puts 31 Special Characters into the collection under the field FieldNo.
Below is a gallery (with wrap at 4) showing the characters

Now put this on the OnChange of the Text Box

ForAll( colChar, If( FieldNo in Self.Text, Collect( colError, {CharError: true} ); Reset(Self) ) )

and this on the OnSelect of the Text Box - you could also in addition put this at Screen OnVisible

Clear(colError)

Now put a Label (this is the warning message) on the screen with this as the Text

"Do not use characters " & Concat( colChar, FieldNo & "" ) & " here"

and this as the Visible

First(colError).CharError

NOTE - I had to use a Collection here as a Variable cannot be set inside a ForAll() statement.

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