requires IS_IN_DB multiple and zero

[Thomas Bellembois]

Hello web2py community,

I have a multiple select widget:

db.PRODUCT.class_of_compounds.requires=[IS_EMPTY_OR(IS_IN_DB(db,
db.CLASS_OF_COMPOUNDS.id, label=db.CLASS_OF_COMPOUNDS._format,
multiple=True, sort=db.CLASS_OF_COMPOUNDS.label, zero='choose'))]

The "zero" field does not appear. If I change multiple from True to
False it appears.
I have probably missed something in the documentation...

How can a user then unselect an item ?

Regards,

Thomas

[Anthony]

The "zero" option is intended for single-selection drop-downs to allow the user to make no selection. This is not necessary for multiple-selection inputs because it is already possible to make no selection simply by not clicking/checking any of the options.

Anthony

[Thomas Bellembois]

Ok, thanks for the answer. It is now clear.

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[jim kaubisch]

old posting, but have a related question - 

In a form dropdown, certainly multiple but probably under some circumstances single, how do I un-select a previous choice without choosing an alternative? Simple example is - currently I have chosen 3 elements of the list, a, b, c and now want to unselect b without choosing an alternative. i.e. I want the resulting list to be a,c (or even empty if I unselect all three), but I see no way of doing that. The "single" case is I have made a choice, now want to undo that choice, i.e. end up with an empty list

Am I missing something obvious?

Thanks

[villas]

Multiple = False

IS_IN_SET(['a', 'b', 'c'], zero=T('choose one'))
To unselect, click 'choose one' instead of whatever was selected.

Multiple = True
Unselect/remove everything which was previously selected.
 
...then submit the form.

[jim kaubisch]

Hi and thanks for the suggestions - 

 You seem to be saying:

          single   - the user should click on "select one" to NOT select ANY - when it's normal semantics is to force the user to selects one?

         multiple -  if 10 things are selected and you want to unselect 1, you need to unselect all 10, remember 9 and and start over again?

Am I misinterpreting?

I was hoping for something simpler/cleaner like - clicking on an entry currently selected unselects it; clicking on it again, reselects it.

[Dave S]

On Saturday, May 25, 2019 at 9:49:28 PM UTC-7, jim kaubisch wrote:

Hi and thanks for the suggestions - 

 You seem to be saying:

          single   - the user should click on "select one" to NOT select ANY - when it's normal semantics is to force the user to selects one?

         multiple -  if 10 things are selected and you want to unselect 1, you need to unselect all 10, remember 9 and and start over again?

If your browser is running on windows or linux, try holding down the control key and clikcing on the unwanted selected item.  On a Mac, the command key might do the same.  On phones and tablets, I dunno.

I don't have an app with a MULTIPLE to try this on.  Also, some behaviors aren't uniform across browsers, much less libraries, so this may work for one user and not for another.

 

Am I misinterpreting?

I was hoping for something simpler/cleaner like - clicking on an entry currently selected unselects it; clicking on it again, reselects it.

The control key feature is basically toggling the selection, but it isolates the item being clicked.  Contrast that with SHIFT-click, which is used for ranges.

Good luck!

/dps

[jim kaubisch]

Thanks, Dave, that did the trick. 

From the little I've tried, "command" seems to work (with Safari) for both single and Multiple. Haven't tried other browsers or the other platforms yet