How to retrieve values of multiple selected options in HTML <select>?

[jamesrhester]

As far as I can tell, if multiple options are selectable in an HTML form, then postpayload(:id) will only return the last value selected, instead of a list of selected values. What is the recommended way to work with multiple options in HTML blocks?

[essenciary]

@jamesrhester If you have multiple inputs with the same name, you need to add the [] suffix to the name - ex name="foo[]". These values will be collected into a vector.

[jamesrhester]

This doesn't seem to work. For the html (part of a form):

<select id=instrs name=instrs[] multiple>
<option value=E>E</option>
<option value=W>W</option>
<option value=K>K</option>
<option value=P>P</option>
</select>

Submitting with the first two options selected and calling print($(postpayload(:instrs))) in route I get
KeyError: key :instrs not found

The relevant section of the raw payload is

Content-Disposition: form-data; name="instrs[]"

E
-----------------------------42394692521712607313909109619
Content-Disposition: form-data; name="instrs[]"

W
-----------------------------42394692521712607313909109619--