[TW5] Checkbox - disable last uncheck

[Mal]

Hi All,

I have a list of tiddlers tagged with category1, category2 or category3 and I would like to filter the list based on checkboxes created using:

<$checkbox tiddler="category1" tag="show">Category 1</$checkbox>
<$checkbox tiddler="category2" tag="show">Category 2</$checkbox>
<$checkbox tiddler="category3" tag="show">Category 3</$checkbox>

However, I need at least one of the checkboxes selected.  In fact, if all three are unchecked, my subsequent list filters fail with an error message.

Is there any way I can ensure that there is always one of the checkboxes in the checked state?

I've looked at a few options involving filters to detect when there is just one category selected and appropriate action widgets, but I'm not clear about how to trigger an action widget without a button.

I guess I could use a select widget instead, with just the legal combinations listed, but seems a bit untidy.

Any suggestions appreciated.

Regards,

Mal

[TonyM]

Mal,

The option you ask for is represented differently, what you seem to be looking for is "radio" options. See this https://tiddlywiki.com/#RadioWidget

It operates on a field rather than using tags, but you can search for these using the has and get operators or fieldname[value]

Regards
Tony

[Mal]

Hi Tony,

I thought about using radio buttons, but I need any combination of the three categories (other than all off). As far as I can see I can only have one of the radio buttons on at any time, unless I'm missing something.

Regards,

Mal

[TonyM]

Mal,

Sorry I missread your question. It is an unusual requirement. I have a hunch, but not the time to work through it now.

Perhaps you could build three/six buttons to toggle each value, using reveal to show/hide like a toggle, each could include a test for the others settings and set a field/tag using an action widget in the button body.

Also sometimes you can share state tiddlers between widgets to get special related settings.

The simplest would be to display a message if none are selected asking for at least one to be selected.

Personaly I use categories for one value (of a number) and subjects for zero or more.

I have another idea, I may write about later, basicaly calling a macro with a filter that lists the possible options and imposes the logic.

Regards
Tony

[TonyM]

Post script

Perhaps you should fix this

However, it makes no sense to have all three checkboxes unchecked and this actually causes errors in my list filters.

Regards
Tony

[Mal]

Tony,

I edited the original post to try to make it a bit clearer.

However, on reflection, I think it's probably too complicated to force the behaviour I'm looking for with either check boxes or radio buttons.  Instead, I will modify the subsequent filters to fail gracefully and produce sensible output if no categories are selected.

Thanks for your input on this.

Regards,

Mal