How to localize my WTForms validation message?

Question

I nearly got my validation message localized as you can see it works for English and Swedish:

English:

Swedish:

But when I switch to Portuguese I get the following error message:

Traceback (most recent call last):
  File "/media/Lexar/montao/lib/webapp2/webapp2.py", line 545, in dispatch
    return method(*args, **kwargs)
  File "/media/Lexar/montao/montaoproject/main.py", line 1749, in post
    current_user=self.current_user,
  File "/media/Lexar/montao/montaoproject/main.py", line 466, in render_jinja
    self.response.out.write(template.render(data))
  File "/media/Lexar/montao/montaoproject/jinja2/environment.py", line 894, in render
    return self.environment.handle_exception(exc_info, True)
  File "/media/Lexar/montao/montaoproject/templates/insert_jinja.html", line 249, in top-level template code
    <ul class="errors">{% for error in form.name.errors %}<li>{{ error }}</li>{% endfor %}</ul>
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 0: ordinal not in range(128)

I think I've had this error message before and I don't know how to handle it. Could you please help me? Why does this error message appear?

The code for my form class is

class AdForm(Form):
    my_choices = [('1', _('VEHICLES')), ('2', _('Cars')), ('3', _('Bicycles'))]

    name = TextField(_('Name'), [validators.Length(min=4, max=50,
                     message=_(u'Name is required') )])
    title = TextField(_('title'), [validators.Required()])
    text = TextAreaField(_('Text'), widget=TextArea())
    phonenumber = TextField(_('Phone number'))
    phoneview = BooleanField(_('Display phone number on site'))
    price = TextField(_('Price'))
    password = PasswordField(_('Password'))
    email = TextField(_('Email'))
    category = SelectField(choices = my_choices, default = '1')

The translation part in my .po file is

msgid "Name is required"
msgstr "É necessário o nome"

My python file begins like this

#!/usr/bin/python
# -*- coding: utf-8 -*-

And AFAIK I've set everything I can to unicode and utf-8.

Thank you for the help

Answer 1

If you want to be able to use unicode characters in your translations, you need to use the ugettext_lazy utility function and not gettext_lazy.
The main difference, as the function name hints, is that ugettext_lazy is unicode when gettext_lazy is not (which makes it not that useful by the way).

While you're at it, you could / should use unicode instead of default strings whenever possible, that is, convert input to unicode ASAP, and encode output as late as possible to the relevant encoding.