相关疑难解决方法(0)

我有一个非常基本的Flask应用程序：

from flask import Flask, render_template
from flask_wtf import FlaskForm
from wtforms_sqlalchemy.fields import QuerySelectField
from wtforms.validators import DataRequired
from flask_sqlalchemy import SQLAlchemy
from wtforms import StringField

db = SQLAlchemy()


app = Flask(__name__)
app.config['SQLALCHEMY_URI'] = 'sqlite:///:memory:'
app.config['SECRET_KEY'] = 'fnord'
db.init_app(app)


class Section(db.Model):
    id = db.Column(db.Integer, primary_key = True)
    name = db.Column(db.Text, nullable = False)
    subject_id = db.Column(db.Integer, db.ForeignKey('subject.id'))
    subject = db.relationship('Subject', back_populates='sections')


class Subject(db.Model):
    id = db.Column(db.Integer, primary_key = True)
    name = db.Column(db.Text, nullable = False)
    sections = db.relationship('Section', back_populates='subject')


def …