WTForms: How to select options in SelectMultipleField?

Question

Choices can be set using form.myfield.choices=[(\"1\",\"Choice1\"), (\"2\",\"Choice2\")]

What is the way to set the selected option?

Answer 1

This is what worked for me (with a dynamic multi select field):

form  = MyForm(request.form, obj=my_obj)
form.tags.choices = [('1', 'abc'), ('2', 'def')]
form.tags.default = ['1', '2']
form.tags.process(request.form)

If I just call form.process(), it loses the default values for the other fields in my form.