A WTForms many2one field which works with nereid and Tryton

gistfile1.py

class Many2OneField(SelectField):
    """
    A select field that works like a many2one field in tryton

    Additional arguments

    :param model: The name of the model
    :param domain: Tryton search domain 
    """
    def __init__(self, label=None, validators=None,
                 model=None, domain=None, **kwargs):
        if model is None:
            raise Exception("Model name cannot be none")
        self.model = model
        self.domain = [] if domain is None else domain
        super(Many2OneField, self).__init__(
            label, validators, int, None, **kwargs
        )

    def iter_choices(self):
        Model = Pool().get(self.model)
        for record in Model.browse(Model.search(self.domain)):
            yield (record.id, record.rec_name, record.id == self.data)

    def pre_validate(self, form):
        Model = Pool().get(self.model)
        exists = Model.search(self.domain + [('id', '=', self.data)])
        if not exists:
            raise ValueError(self.gettext('Not a valid choice'))