How to add custom fields order to WTForms

forms.py

from collections import OrderedDict

# ...

class OrderFormMixin(object):
    '''
    To apply add to Meta 'order' iterable
    '''
    def __init__(self, *args, **kwargs):
        super(OrderFormMixin, self).__init__(*args, **kwargs)

        field_order = getattr(self.meta, 'order', [])
        if field_order:
            visited = []
            new_fields = OrderedDict()

            for field_name in field_order:
                if field_name in self._fields:
                    new_fields[field_name] = self._fields[field_name]
                    visited.append(field_name)

            for field_name in self._fields:
                if field_name in visited:
                    continue
                new_fields[field_name] = self._fields[field_name]

            self._fields = new_fields
            
            
# ...


class MyModelForm(OrderFormMixin, ModelForm):
    class Meta:
        model = MyModel
        order = ('field1', 'field2', )