Redo SingleChoiceSelection for better differentiation between required and optional selections

[patritzenfeld]

• forces a non-empty input for required dropdown selections
• allows for directly optional dropdowns and radio buttons, thus removing the need to add --- options manually

[horriblename]

this should probably be value=""

so I can make use of <select required> to get the browser's own pre-submit checks like this:

https://stackoverflow.com/a/6048891

[patritzenfeld]

This should already be the case if you use SingleChoiceSelection. This value="None" is only offered for form type Maybe SingleChoiceSelection. If the field is required, then this is used instead:

flex-tasks/flex-tasks/src/FlexTask/Widgets.hs

Lines 141 to 145 in 14342ca

	$newline never
	<select ##{theId} name=#{name} :req:required *{attrs}>
	$if req
	<option value="" selected disabled>_{MsgSelectNone}
	^{inside}

But I guess I should revise my custom selectField function to be less confusing. I just did a quick copy and edit on the standard Yesod version which resulted in messy code.

[horriblename]

currently, with formify (Nothing @SingleChoiceSelection), I'll get a dropdown where the value defaults to the first real value, and the None option is disabled:

I want it to default to None instead (the table is big so making it default to None makes it easy for students to see which dropdown they have not yet answered), but I also want the required check to take effect.

For this to work, perhaps what I need is just removing disabled from https://github.com/fmidue/flex-tasks/pull/222/changes#diff-26588820d6d6d6eb9930e0b89192489214299acf12c3b5043f1b362e02333b7bR774? what do you think ?

[patritzenfeld]

Okay, I guess the behaviour is different between browsers. It did initially select the None option when I tried it on my setup, but did not allow reselecting it. I I will just remove the disabled attribute then.

[patritzenfeld]

What browser are you using? I'd like to take a look at this again on Tuesday.

[horriblename]

firefox