首页列表显示全部问答，完成问答详情页布局。

2. 首页列表显示全部问答：
   1. 将数据库查询结果传递到前端页面 Question.query.all()
   2. 前端页面循环显示整个列表。
   3. 问答排序
3. 完成问答详情页布局：
   1. 包含问答的全部信息
   2. 评论区
   3. 以往评论列表显示区。
4. 在首页点击问答标题，链接到相应详情页。

from flask import Flask,render_template,request,redirect,url_for,session
from flask_sqlalchemy import SQLAlchemy
import config
from datetime import datetime
from functools import wraps

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)
#db.create_all()

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)
    creatTime=db.Column(db.DateTime,default=datetime.now)
    authorID=db.Column(db.Integer,db.ForeignKey('User.id'))
    author=db.relationship('User',backref=db.backref('question'))
#db.create_all()


@app.route('/')
def home():
    context={
        'question': Question.query.all()
    }
    return render_template('shouye.html',**context)

@app.route('/question_detail/')
def question_detail():
    return render_template('question_detail.html')

@app.route('/sign_in/',methods=['GET','POST'])
def sign_in():
    if request.method == 'GET':
        return render_template('denglu1.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
                session.permanent = True
                return redirect(url_for('home'))
            else:
                return 'password error'
        else:
            return 'username is not existed.'


@app.route('/sign_up/',methods=['GET','POST'])
def sign_up():
    if request.method == 'GET':
        return render_template('zhuce.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:
            user1 = User(username=username, password=password)
            db.session.add(user1)
            db.session.commit()
            return redirect(url_for('home'))

@app.context_processor
def mycontext():
    username=session.get('user')
    if username:
        return {'username':username}
    else:
        return {}
@app.route('/logout/') #注销
def logout():
    session.clear()
    return redirect(url_for('home'))

def loginFirst(func):
    @wraps(func)
    def wrapper(*args,**kwargs):
        if session.get('user'):
            return func(*args, **kwargs)
        else:
            return redirect(url_for('sign_in'))
    return wrapper

@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')
        authorID =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 'title existed'
        else:
            questions = Question(title=title, detail=detail, authorID=authorID)
            questions.author = user
            db.session.add(questions)
            db.session.commit()
            return redirect(url_for(('home')))

if __name__ == '__main__':
    app.run(debug=True)

{% extends'base.html' %}
{% block title %}
    Home
{% endblock %}
{% block head %}
    <link rel="stylesheet" href="{{ url_for('static',filename='css/shouye.css')}}" type="text/css">
{% endblock %}
{% block main %}
<body>

<br>
{#<img id="pig" src="../static/images/pig.jpg">#}
<ul class="comment">
    <img class="comment_pic"  src="../static/images/comment.png">
    <p class="wenzi">Question</p>
    {% for foo in question %}

    <li class="detail">
        <span class="icon" aria-hidden="true"><img src="../static/images/icon.jpg"></span>
        <a href="#" style="float: left;margin:3px auto; line-height:12px;">{{ foo.author.username }}</a>
         <span class="badge">{{ foo.creatTime }}</span>
        <br><hr>
        <a href="{{ url_for('question_detail') }}" class="title">&nbsp;{{ foo.title }}</a>
        <p class="neirong">&nbsp;{{ foo.detail }}</p>
    </li>

    {% endfor %}

</ul>

</body>
{% endblock %}

{% extends'base.html' %}
{% block title %}
    Home
{% endblock %}
{% block head %}
    <link rel="stylesheet" href="{{ url_for('static',filename='css/question_detail.css')}}" type="text/css">
{% endblock %}
{% block main %}
<body>
<div class="detail">
    <div class="detail_left">
    <h2>title</h2>
    <a>username</a>
<span class="badge">creatTime</span>
    <hr>
    <a>detail</a>
    <hr>
    <textarea name='comment' class="form-control" rows="8" id="questionDetail"></textarea>
    <br><button class="btn-default">发布</button>
    <p>评论：</p>
    <li class="comment">
        <span class="icon" aria-hidden="true"><img src="../static/images/icon.jpg"></span>
        <a href="#" style="float: left;margin:3px auto; line-height:12px;">username</a>
         <span class="badge2">creatTime</span>
        <br><hr>
        <p class="neirong">detail</p>
    </li>
     <li class="comment">
        <span class="icon" aria-hidden="true"><img src="../static/images/icon.jpg"></span>
        <a href="#" style="float: left;margin:3px auto; line-height:12px;">username</a>
         <span class="badge2">creatTime</span>
        <br><hr>
        <p class="neirong">detail</p>
    </li>

</div>
</div>
</body>
{% endblock %}