使用WTForms不更新的动态选择字段

Question

我正在尝试使用wtforms和sqlalchemy创建一个动态选择字段,但是当从数据库中插入或删除项目时它不会更新.这是我的代码:

class UserForm(Form):
    username = StringField('Username', validators=[DataRequired()])
    password = PasswordField('Password', validators=[DataRequired()])
    job = SelectField(
        'Job',
        validators=[DataRequired()],
        choices=[(a.id, a.name) for a in Job.query.order_by(Job.name)]
    )

和数据库模型:

class Job(db.Model):
    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
    name = db.Column(db.String)

    def __init__(self, name):
        self.name = name

    def __repr__(self):
        return '<Job %s>' % self.name

它成功显示了选择字段中的作业,但是如果您修改了表,则它不会更新,除非您完全重新启动应用程序.

Answer 1

您应该在创建表单对象时初始化表单选项:

class UserForm(Form):
    username = StringField('Username', validators=[DataRequired()])
    password = PasswordField('Password', validators=[DataRequired()])
    job = SelectField(
        'Job',
        validators=[DataRequired()]
    )

    def __init__(self, *args, **kwargs):
        super(UserForm, self).__init__(*args, **kwargs)
        self.job.choices = [(a.id, a.name) for a in Job.query.order_by(Job.name)]

或者在视图中:

form = UserForm()
form.job.choices = [(a.id, a.name) for a in Job.query.order_by(Job.name)]