• 编写要求登录的装饰器

from functools import wraps

def loginFirst(func): #参数是函数

@wraps(func)

      def wrapper(*args, ** kwargs): #定义个函数将其返回

          #要求登录

          return func(*args, ** kwargs)

      return wrapper #返回一个函数

• 应用装饰器，要求在发布前进行登录，登录后可发布。

@app.route('/question/',methods=['GET','POST']) @loginFirst def question():

• 建立发布内容的对象关系映射。

class Question(db.Model):

• 完成发布函数。

保存到数据库。

重定向到首页。

from flask import Flask,render_template,request,redirect,url_for,sessionfrom flask_sqlalchemy import SQLAlchemyfrom functools import wrapsfrom datetime import datetimeimport configapp = Flask(__name__)app.config.from_object(config)db=SQLAlchemy(app)db = SQLAlchemy(app)# 创建用户模型class User(db.Model):    __tablename__ = 'user'    id = db.Column(db.Integer, primary_key=True, autoincrement=True)    username = db.Column(db.String(20), nullable=False)    password = db.Column(db.String(20), nullable=False)class Question(db.Model):    __tablename__ = 'question'    id = db.Column(db.Integer, primary_key=True, autoincrement=True)    question = db.Column(db.String(100), nullable=False)    questionDetail = db.Column(db.Text, nullable=False)    creat_time = db.Column(db.DateTime, default=datetime.now)    author_id = db.Column(db.Integer, db.ForeignKey('user.id'))    author = db.relationship('User', backref=db.backref('question'))#db.create_all()@app.route('/')def homepage():    return render_template("homepage.html")@app.route('/login/',methods=['GET','POST'])def login():    if request.method == "GET":        return render_template("login.html")    else:        username = request.form.get("username")        password = request.form.get("password")        user = User.query.filter(User.username == username).first()        if user:            if user.password == password:                session['user'] = username                sessionpermanent = True                return redirect(url_for('homepage'))            else:                return 'password error'        else:            return 'username is not existed'@app.route("/register/",methods=['GET','POST'])def register():    if request.method == "GET":        return render_template("register.html")    else:        username = request.form.get("username")        password = request.form.get("password")        user = User.query.filter(User.username == username).first()        if user:            return 'username existed.'        else:            user = User(username=username, password=password)            db.session.add(user)            db.session.commit()            return redirect(url_for('login'))@app.context_processordef mycontext():    usern = session.get('user')    if usern:        return {'username':usern}    else:        return {}@app.route('/logout/')def logout():    session.clear()    return render_template("homepage.html")def log(func): #参数是函数    @wraps(func)    def wrapper(*args, **kwargs): #定义个函数将其返回        if session.get('user'):            return func(*args, **kwargs)        else:            return redirect(url_for('login'))    return wrapper #返回一个函数@app.route('/question/', methods=['GET' , 'POST'])@logdef question():    if request.method == 'GET':        return render_template('question.html')    else:        question = request.form.get('question')        questionDetail = request.form.get('questionDetail')        author_id = User.query.filter(User.username == session.get('user')).first().id        question = Question(question = question, questionDetail = questionDetail, author_id = author_id)        db.session.add(question)        db.session.commit()        return redirect(url_for('homepage'))if __name__ == '__main__':     app.run(debug=True)