从首页问答标题到问答详情页

1. 主PY文件写视图函数，带id参数。 

   @app.route('/detail/<question_id>')
   def detail(question_id):
       quest = 
       return render_template('detail.html', ques = quest) 

2. 首页标题的标签做带参数的链接。
         {{ url_for('detail',question_id = foo.id) }}
   
   
3. 在详情页将数据的显示在恰当的位置。 

   {{ ques.title}}
   {{ ques.id  }}{{  ques.creat_time }}

   {{ ques.author.username }} 
   {{ ques.detail }}

4. 建立评论的对象关系映射：

   class Comment(db.Model):
       __tablename__='comment'

5.  尝试实现发布评论。

   from flask import Flask,render_template,request,redirect,url_for,session
   from flask_sqlalchemy import SQLAlchemy
   
   from datetime import datetime
   from functools import wraps
   import config
   
   app = Flask(__name__)
   app.config.from_object(config)
   db = SQLAlchemy(app)
   
   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)
       nickname = db.Column(db.String(20))
   
   class Question(db.Model):
       __table__name = 'question'
       id = db.Column(db.Integer, primary_key=True, autoincrement=True)
       title = db.Column(db.String(100), nullable=False)
       detail = 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'))
   
   class Comment(db.Model):
       __tablename__ = 'comment'
       id = db.Column(db.Integer, primary_key=True, autoincrement=True)
       author_id = db.Column(db.Integer, db.ForeignKey('user.id'))
       question_id = db.Column(db.Integer, db.ForeignKey('question.id'))
       detail = db.Column(db.Text,nullable=False)
       creat_time = db.Column(db.DateTime,default=datetime.now)
       question = db.relationship('Question', backref=db.backref('comments'))
       author = db.relationship('User', backref=db.backref('comments'))
   #db.create_all()
   
   
   @app.route('/')
   def index():
       context = {
             'questions': Question.query.all()
       }
       return render_template('index.html',**context)
   
   @app.route('/login/',methods=['GET','POST'])
   def login():
       if request.method == 'GET':
           return render_template('login.html')
       else:
           usern = request.form.get('username')
           passw = request.form.get('password')
           user = User.query.filter(User.username == usern).first()
           if user:
               if user.password == passw:
                   session['user'] = usern
                   session.permanent = True
                   return redirect(url_for('index'))
               else:
                   return 'password error'
           else:
               return 'username is not existed.'
   
   @app.route('/regist/',methods=['GET','POST'])
   def regist():
       if request.method == 'GET':
           return render_template('regist.html')
       else:
           usern = request.form.get('username')
           nickn = request.form.get('nickname')
           passw = request.form.get('password')
           user = User.query.filter(User.username == usern).first()
           if user:
               return 'username existed.'
           else:
               user1 = User(username=usern,password=passw,nickname=nickn)
               db.session.add(user1)
               db.session.commit()
               return  redirect(url_for('login'))
   
   @app.route('/logout')
   def logout():
       session.clear()
       return redirect(url_for('index'))
   
   def loginFirst(func):
       @wraps(func)
       def wrapper(*args,**kwargs):
           if session.get('user'):
               return func(*args,**kwargs)
           else:
               return redirect(url_for('login'))
       return wrapper
   
   @app.context_processor
   def mycontext():
       usern = session.get('user')
       if usern:
           return {'username': usern}
       else:
           return {}
   
   @app.route('/question/',methods=['GET','POST'])
   @loginFirst
   def question():
       if request.method == 'GET':
           return render_template('question.html')
       else:
           title = request.form.get('title')
           detail = request.form.get('detail')
           author_id = User.query.filter(User.username == session.get('user')).first().id
           user = User.query.filter(User.username == session.get('user')).first()
           question = Question.query.filter(Question.title == title).first()
           if question:
               return 'question existed.'
           else:
               question = Question(title=title, detail=detail, author_id=author_id)
               question.author = user
               db.session.add(question)
               db.session.commit()
               return redirect(url_for('index'))
   
   @app.route('/detail/<question_id>')
   def detail(question_id):
       quest = Question.query.filter(Question.id == question_id).first()
       return render_template('detail.html',ques = quest)
   
   
   if __name__ == '__main__':
       app.run(debug=True)
   

   　　

   {% extends 'base.html' %}
   {% block title %}首页{% endblock %}
   
   {% block head %}
       <link rel="stylesheet" href="{{ url_for('static',filename='css/index.css')}}" type="text/css">
   {% endblock %}
   
   {% block main %}
       <p>{{ username }}欢迎您来到首页！</p>
   <div id="list-container">
       <ul class="note-list" style="margin:80px auto;width: 1000px;height:800px;background: #FFF;border-radius: 20px;opacity:0.6;filter:alpha(opacity=60);list-style: none">
           {% for foo in questions %}
               <li class="note-list-item">
                   <div class="contain">
                       <span class="glyphion glyphion-leaf" aria-hidden="true"></span>
                       <a href="{{ url_for('detail',question_id = foo.id)}}">{{ foo.title }}</a>
                       <p style="width: 450px;"> 详情 {{ foo.detail }}</p>
                       <span class="glyphion glyphion-user" aria-hidden="true"></span>
                       <a href="#">{{ foo.author.username }}</a>
                       <br>
                       <span class="badge">{{ foo.creat_time }}</span>
                   </div>
               </li>
           {% endfor %}
       </ul>
   </div>
   {% endblock %}