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Data-Aware Checkbox: ValueUnchecked problem

Posted on 1998-03-03
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Last Modified: 2010-04-04
I am using data-aware check boxes, and I want the boxes to be unchecked if the value in the respective field is NULL, ie nothing there, a blank field, no data. As if no data had been entered yet.

I've tried the following and they don't work:

1. DBCheckBox.ValueUnchecked := ''; (no spaces)

2. DBCheckBox.ValueUnchecked := NULL;

3. DBCheckBox.ValueUnchecked := ' '; (1 space)

Can you help me here?
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Question by:jsweby
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Expert Comment

by:ZifNab
ID: 1360039
Hi jsweby,

You have to use IsNull

eg. Table1.FieldByName('CheckThis').IsNull

Returns true if field content is empty, otherwise false.
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Author Comment

by:jsweby
ID: 1360040
The ValueChecked and ValueUnchecked properties of DBCheckBox cannot take Boolean values, so how do you suggest I implement your answer? The value on the right-hand side of the property ValueUnchecked has to be of type String, as in my original question above.
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Expert Comment

by:ZifNab
ID: 1360041
Wow, don't eat my heart out!

What about ....ValueUnchecked := #0

Besides my first answer can be used if nothing else helps or nothing else is possible :

e.g. DBCheckBox.Checked := (Table1.FieldByName('CheckThis').IsNull = False);


Q : What type is the underlying data?

I just want to help, you know.

Regards, Zif.
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Author Comment

by:jsweby
ID: 1360042
Hi ZifNab,

Sorry if you got the impression I was having a go at you, I wasn't!

I've just realised that this component DOES have a Checked value which can be set to True or False. I thought it didn't, which I thought was strange seeing as the standard CheckBox component does. That's why I've been trying to get this ValueUnchecked to work, which only takes a String and not a Boolean value.

Thanks for trying to help, sorry you took my comments the wrong way!
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Author Comment

by:jsweby
ID: 1360043
Zif,

If you submit your answer again, I'll give you the points. I can't see how to do it from a comment
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Accepted Solution

by:
ZifNab earned 50 total points
ID: 1360044
Hi jsweby,

Sorry about my last comment, had a bad day and couldn't take much at that time ...

What about ....ValueUnchecked := #0

or DBCheckBox.Checked := (Table1.FieldByName('CheckThis').IsNull = False);

Regards, Zif.
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