Wtforms: How to generate blank value using select fields with dynamic choice values

Question

I'm using Flask with WTForms (doc) on Google App Engine. What is the best way to generate an field with an empty value for a select field?

form.group_id.choices = [(g.key().id(), g.name) for g in Group.all().order('name')]

Is there something like "blank=True" for the form field?

myfield = wtf.SelectField()

Dort

Answer 1

Can you just prepend an empty pair to the list?

form.group_id.choices.insert(0, ('', ''))

Relict

Answer 2

If it's a QuerySelectField, you can add parameters like this:

allow_blank=True, blank_text=u'-- please choose --'

Micahmicawber

Answer 3

I prefer such a way:

form.group_id.choices = ['none'] + [(g.key().id(), g.name) for g in Group.all().order('name')]

and that's enough - you don't need to deal with 'none' value.

Potluck