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) }}
   

   from flask import Flask, render_template,request,redirect,url_for,session
   from flask_sqlalchemy import SQLAlchemy
   import config
   from functools import wraps
   from datetime import datetime
   
   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(100), nullable=False)
       password= db.Column(db.String(500), nullable=False)
   
   
   class Question(db.Model):
       __tablename__ = '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)
       create_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'))
       create_time = db.Column(db.DateTime, default=datetime.now)
       detail = db.Column(db.Text, nullable=False)
       question = db.relationship('Question', backref=db.backref('comments'))
       author = db.relationship('User', backref=db.backref('comments'))
   
   db.create_all()
   
   
   @app.route('/')
   def hello_world():
       return render_template('base.html')
   @app.route('/zhuce/',methods=['GET','POST'])
   
   def zhuce():
       if request.method == 'GET':
           return render_template('zc.html')
       else:
           username = request.form.get('username')  # 获取form中的数据
           password = request.form.get('password')  # 获取form中的数据
           # email = request.form.get('email')  # 获取form中的数据
           user = User.query.filter(User.username ==username).first()
           if user:
               return'用户已存在'
           else:
               user = User(username = username,password=password)
               db.session.add(user)
               db.session.commit()
               return redirect(url_for('denglu'))
   
   @app.route('/denglu/',methods=['GET','POST'])
   def denglu():
       if request.method=='GET':
           return render_template('dl.html')
       else:
           username = request.form.get('username')
           password = request.form.get('password')
   
           user=User.query.filter(User.username==username).first()
           #判断用户名是否存在
           if user:
               session['user']=username
               session.permanent=True
               if user.password==password:
                   return redirect(url_for('shouye'))
               else:
                   return '密码错误'
           else:
               return '此用户不存在'
   
   @app.context_processor
   def mycontext():
       usern=session.get('user')
       if usern:
           return {'username':usern}
       else:
           return{}
   
   @app.route('/logout/')
   def logout():
       session.clear();
       return redirect(url_for('shouye'))
   
   def log(func): #参数是函数
       @wraps(func)
       def wrappers(*args,** kwargs): #定义个函数将其返回
           if session.get('user'):
               return func(*args,**kwargs)
           else:
               return redirect(url_for('denglu'))
       return wrappers #返回一个函数
   
   
   @app.route('/shouye/')
   def shouye():
       context = {
           'questions':Question.query.order_by('create_time').all()
       }
       return render_template('hh.html',**context)
   
   @app.route('/wenda/',methods=['GET','POST'])
   @log
   def wenda():
       if request.method=='GET':
           return render_template('wd.html')
       else:
           title=request.form.get('title')
           detail=request.form.get('detail')
           author_id=User.query.filter(User.username==session.get('user')).first().id
           question=Question(title=title,detail=detail,author_id=author_id)
           db.session.add(question)#保存到数据库
           db.session.commit()#提交
       return redirect(url_for('shouye'))#跳转
   
   @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)

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。

   {% extends 'base.html' %}
   {% block title %}
       问答详情
   {% endblock %}
   {% block main %}
       <div class="box">
           <h3 href="#" >{{ ques.title }}</h3><small> {{ ques.author.username }}<span class="badge" style="margin-left: 75%">{{ ques.create_time }}</span></small>
           <hr>
           <p>{{ ques.detail }}</p>
           <hr>
           <form>
               <div><textarea class="form-control" id="comment" rows="3" style="margin-left: 1%" name="comment" placeholder="write your comment"></textarea><br></div>
               <button type="submit" >发送</button>
           </form>
         <h4>评论:</h4>
            <ul class="list-group">
                   <li class="list-group-item">
                       <img style=" 30px" src="{{ url_for('static',filename='css/touxiang.jpg') }}" alt="64">
                       <a href="#"></a><br>
                       <p style="align-content: center"></p>
                       <span class="badge" style="margin-left: 60%"></span>
                       <p style="margin-left: 25%"></p><br>
                   </li>
           </ul>
   
       </div>
   {% endblock %}