wtform表单中动态添加的字段无法显示

Question

1、form构造函数中动态添加字段，打开浏览器第一次仅能显示form属性申明中的字段：projectIdentifier和submit，无法显示构造函数中动态添加的字段，必须刷新一遍才能显示动态添加的字段，有木有办法不刷新，由于动态字段中的内容较多，不想在类属性申明阶段一个个写死。
主要代码如下：

app.order.forms.py

class EmployeeForm(Form):
    projectIdentifier = StringField('项目编号', validators=[
        DataRequired('请输入项目编号'),
        Length(min=4, max=25, message='length must between 4 and 25')
    ])
    submit = ButtonField('确定')

    def __init__(self, *args, **kwargs):
        super(EmployeeForm, self).__init__(*args, **kwargs)
        for job in Job.query.all():
            setattr(self.__class__, job.name, SelectField(job.label, coerce=int))
        for job in Job.query.all():
            getattr(self, job.name).choices = [(user.id, user.username) for user in User.query.all()]
 

app.models.py

class Job(db.Model):
    __tablename__ = 'jobs'
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(64), unique=True)
    duties = db.Column(db.Integer)
    label = db.Column(db.String(64))
    description = db.Column(db.String(64))
    users = db.relationship('Registration', backref='job', lazy='dynamic')    

app.order.view.py

@order.route('/employee')
def employee():
    form = EmployeeForm()
    projectNo = request.args.get('projectNo')
    return render_template('order/employee.html', projectNo=projectNo,form=form)

template/order/employee.html

前段使用quick_form渲染
{{ wtf.quick_form(form) }}
2、尝试：考虑过直接在类属性声明中添加，但提示Job.query.all()没有绑定，查过stackover，不能在form申明时进行查询，好像此路不通

#app.order.forms.py
    class EmployeeForm(Form):
        projectIdentifier = StringField('项目编号', validators=[
            DataRequired('请输入项目编号'),
            Length(min=4, max=25, message='length must between 4 and 25')
        ])
        submit = ButtonField('确定')
        for job in Job.query.all():
                vasr()[job.name]=SelectField(job.label, coerce=int) 
                 
        def __init__(self, *args, **kwargs):
            super(EmployeeForm, self).__init__(*args, **kwargs)
            for job in Job.query.all():
                getattr(self, job.name).choices = [(user.id, user.username) for user in User.query.all()]