首页列表显示全部问答，完成问答详情页布局。

1. 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
2. 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。
3. 在首页点击问答标题，链接到相应详情页。

py：

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(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)
    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'))

db.create_all()


@app.route('/')
def daohang():
    context={
        'questions':Question.query.order_by('creat_time').all()
    }
    return render_template('index.html',**context)

@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)


@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, User.password == password).first()
        if user:
            session['user'] = username
            session.permanent = True
            return redirect(url_for('daohang'))
        else:
            return 'error username or password'



@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('regist'))


@app.route('/regist/', methods=['GET', 'POST'])
def regist():
    if request.method == 'GET':
        return render_template('regist.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'))


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.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
        question = Question(title=title, detail=detail, author_id=author_id)
        db.session.add(question)
        db.session.commit()
        return redirect(url_for('daohang'))

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

detail.html:

{% extends 'daohang.html' %}
{% block title %}问答详情{% endblock %}

{% block main %}
    <div class="page-header">
        <h3>Title {{ ques }}<br><small>author{{ ques.author_id }}{{ ques.create_time }}</small>></h3>

    </div>
    <p class="lead">detail{{ ques.detail }}</p>
    <hr>

    <form action="{{ url_for('question') }}"method="post" style="...">
        <div class="form-group">
            <textarea name="new_comment" id="new-comment" class="form-control" rows="3"
                      placeholder="write your comment"></textarea>
        </div>
        <button type="submit" class="btn btn-default">发送</button>

    </form>
    <ul class="list-group" style="margin: 10px"...></ul>>
{% endblock %}

index.html:

{% extends "daohang.html" %}
{% block title %}首页{% endblock %}

{% block main %}
   <p>{{ user }}contextx</p>

   <ul class="list-group" style="...">
       {% for foo in questions %}
           <li class="list-group-item">
           <span class="glyphicon glyphicon-leaf" aria-hidden="true"></span>
           <a href="#">{{ foo.author.username }}</a>
           <br>
           <a href="{{ url_for('detail',question_id=foo.id) }}">{{ foo.title }}</a>
           <span class="badge">{{ foo.creat_time }}</span>
           <p style="...">{{ foo.detail }}</p>

           </li>

       {% endfor %}
   </ul>
{% endblock %}