[Solved] Enhancing QDateEdit to allow for null/empty dates
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In our application we use a composite widget with a QDateTimeEdit and a checkbox, which when checked, enables the QDate/TimeEdit and when unchecked represents a null date. We do not have problems with usability with that, no complaints from our users. Also, it is only one click to reset it to null compared to 3 times delete the date :-) And not to mention that you cannot reset the date with the calendar popup (I'm sure there are users out there which do not know how to delete the date from the internal line edit)
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No, I mean that by using CSS, you are able to position the clear button (and the other widgets) inside the QDateEdit itself in a nice way, and make sure that Qt doesn't draw over or under it. See the link I included for an idea of what I mean. It will look more natural that way. The CSS won't rid you of having to overlay something like a QLabel, unless you would accept a completely empty box as an acceptable representation of a null date. In that case, you could use CSS (or any other way to set the color) to make the text color the same as the background color.
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[quote author="Volker" date="1294829498"]In our application we use a composite widget with a QDateTimeEdit and a checkbox, which when checked, enables the QDate/TimeEdit and when unchecked represents a null date. We do not have problems with usability with that, no complaints from our users. Also, it is only one click to reset it to null compared to 3 times delete the date :-) And not to mention that you cannot reset the date with the calendar popup (I'm sure there are users out there which do not know how to delete the date from the internal line edit)[/quote]
Thank you for the suggestion from the "real world". Sound like a interesting alternative UI design to the use of a clear button.
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[quote author="Andre" date="1294829795"]No, I mean that by using CSS, you are able to position the clear button (and the other widgets) inside the QDateEdit itself in a nice way, and make sure that Qt doesn't draw over or under it. See the link I included for an idea of what I mean. It will look more natural that way. The CSS won't rid you of having to overlay something like a QLabel, unless you would accept a completely empty box as an acceptable representation of a null date. In that case, you could use CSS (or any other way to set the color) to make the text color the same as the background color.
[/quote]I understand! Thank you for making this crystal clear.
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I have exactly the same problem: I try to migrate a MS Access application to Qt. There is a date field for a products table. For some products I have to store a "best before" date ("Mindesthaltbarkeit"), but for several products (like music instruments, jewels, etc...) there is no "best before" date. In MS access the user simply leave the field empty.
I have transfered the MS Access database to a sqlite3 database and now the new Qt frontend displays always the last displayed "best before" date when the value is null...
It would be great, if the QDateEdit can be evolved to handle null values as well.
Thanks,
Markus
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We have created an extended version of QDateEdit that can handle null dates.
"QDateEditEx":https://github.com/doberkofler/QDateEditEx -
First of all: thanks for posting your solution.
However, it seems to me the class is not correct. It overrides date(), time() and dateTime(), but these functions are not virtual in [[doc:QDateEdit]] of which QDateEditEx is a subclass. That seems dangerous to me, as it won't work as a drop-in replacement of QDateEdit. If you use a QDateEditEx where a QDateEdit is expected, the results of calling these functions will be those defined in QDateEdit, not those from QDateEditEx.
Isn't it possible to provide the same feature by just reimplementing dateTimeFromText and textFromDateTime to work with empty strings and null dates? I didn't try it, but that seems to be the correct solution. Of course the features you have with the nullable property and the clear button are quite nice. Having the clear button in a date edit that accepts null input is a nice touch and also communicates to the user that an empty value is acceptable.
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I have found a DateValidator that works fine with a QLineEdit and accepts null values:
http://www.qtforum.de/forum/viewtopic.php?f=7&t=900
Best regards,
Markus
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this thread is very old, but i still may help others.
The QDateTimeEdit (and it's derives) have the method
@virtual QString textFromDateTime( const QDateTime & dateTime ) const;@
So you could subclass it and return any string you want and it will be displayed.
I don't think that QDateTimeEdit lets you set a invalid QDateTime value, but you could set a property on the widget to indicate a valid/invalid value state and return an appropriate custom string for invalid values or just return the base class implementation's return value. -
Here's another ugly workaround :
dateEdit->setSpecialValueText( " " ); dateEdit->setDate( QDate::fromString( "01/01/0001", "dd/MM/yyyy" ) );- as the date is below the minimum, the widgets shows the special value text ( a space in this example )
- note that special text does not work with an empty string
