flask-sqlalchemy+wtforms实现标签动态更新

我的目录结构：

1. 创建一个ext.py将db的初始化隔离

   from flask_sqlalchemy import SQLAlchemy
   
   db = SQLAlchemy()
   

2. 在实例化form对象时再传入db

   from flask import Blueprint, request, render_template
   from app01.ext import db
   from app01.views.user.forms import LoginForm
   
   blue_user = Blueprint('user', __name__, template_folder='./templates', url_prefix='/user')
   
   
   @blue_user.route('/', methods=['get', 'post'])
   def index():
       if request.method == 'GET':
           form = LoginForm(db=db)
           return render_template('html.html', form=form)
       else:
           form = LoginForm(formdata=request.form,db=db)
           print(form.validate())
           print(form.data)
           print(form.errors)
           return render_template('html.html', form=form)
   

from wtforms import widgets, validators, Form
from wtforms.fields import simple, html5, core
from app01.views.user import models


class LoginForm(Form):
    def __init__(self, db=None, **kwargs):
        super().__init__(**kwargs)
        self.name.choices = db.session.query(models.User.id, models.User.username).order_by('id').all()

    name = core.SelectMultipleField(
        label='城市',
        choices=[],
        coerce=int
    )

1. 每次实例化form即每次请求时从数据库拿到数据
2. coerce=int

对于俺这种小白来说，sqlalchemy太容易出现循环导入了，所以干脆把实例化踢出去比较好。导包都能死锁，我也是醉了，搞得一个头两个大。T_T