一、flask实现的分页组件

#!/usr/bin/python
# -*- coding: utf-8 -*-

__author__ = 'mrs.wc'
__filename__ = 'page_tools'
__datetime__ = '2018/3/1 21:39'

from urllib import urlencode, quote, unquote

class Pagination(object):
    """
    自定义分页
    """

    def __init__(self, current_page, total_count, base_url, params, per_page_count=10, max_pager_count=5):
        try:
            current_page = int(current_page)
        except Exception as e:
            current_page = 1
        if current_page <= 0:
            current_page = 1
        self.current_page = current_page
        # 数据总条数
        self.total_count = total_count

        # 每页显示10条数据
        self.per_page_count = per_page_count

        # 页面上应该显示的最大页码
        max_page_num, div = divmod(total_count, per_page_count)
        if div:
            max_page_num += 1
        self.max_page_num = max_page_num

        # 页面上默认显示11个页码（当前页在中间）
        self.max_pager_count = max_pager_count
        self.half_max_pager_count = int((max_pager_count - 1) / 2)

        # URL前缀
        self.base_url = base_url

        # request.GET
        import copy
        params = copy.deepcopy(params)
        # params._mutable = True
        get_dict = params.to_dict()
        # 包含当前列表页面所有的搜/索条件
        # {source:[2,], status:[2], gender:[2],consultant:[1],page:[1]}
        # self.params[page] = 8
        # self.params.urlencode()
        # source=2&status=2&gender=2&consultant=1&page=8
        # href="/hosts/?source=2&status=2&gender=2&consultant=1&page=8"
        # href="%s?%s" %(self.base_url,self.params.urlencode())
        self.params = get_dict

    @property
    def start(self):
        return (self.current_page - 1) * self.per_page_count

    @property
    def end(self):
        return self.current_page * self.per_page_count

    def page_html(self):
        # 如果总页数 <= 11
        if self.max_page_num <= self.max_pager_count:
            pager_start = 1
            pager_end = self.max_page_num
        # 如果总页数 > 11
        else:
            # 如果当前页 <= 5
            if self.current_page <= self.half_max_pager_count:
                pager_start = 1
                pager_end = self.max_pager_count
            else:
                # 当前页 + 5 > 总页码
                if (self.current_page + self.half_max_pager_count) > self.max_page_num:
                    pager_end = self.max_page_num
                    pager_start = self.max_page_num - self.max_pager_count + 1  # 倒这数11个
                else:
                    pager_start = self.current_page - self.half_max_pager_count
                    pager_end = self.current_page + self.half_max_pager_count

        page_html_list = []
        # {source:[2,], status:[2], gender:[2],consultant:[1],page:[1]}
        # 首页
        self.params['page'] = 1
        first_page = '<li><a href="%s?%s">首页</a></li>' % (self.base_url, urlencode(self.params),)
        page_html_list.append(first_page)
        # 上一页
        self.params["page"] = self.current_page - 1
        if self.params["page"] < 1:
            pervious_page = '<li class="disabled"><a href="%s?%s" aria-label="Previous">上一页</span></a></li>' % (
                self.base_url, urlencode(self.params))
        else:
            pervious_page = '<li><a href = "%s?%s" aria-label = "Previous" >上一页</span></a></li>' % (
                self.base_url, urlencode(self.params))
        page_html_list.append(pervious_page)
        # 中间页码
        for i in range(pager_start, pager_end + 1):
            self.params['page'] = i
            if i == self.current_page:
                temp = '<li class="active"><a href="%s?%s">%s</a></li>' % (self.base_url, urlencode(self.params), i,)
            else:
                temp = '<li><a href="%s?%s">%s</a></li>' % (self.base_url, urlencode(self.params), i,)
            page_html_list.append(temp)

        # 下一页
        self.params["page"] = self.current_page + 1
        if self.params["page"] > self.max_page_num:
            self.params["page"] = self.current_page
            next_page = '<li class="disabled"><a href = "%s?%s" aria-label = "Next">下一页</span></a></li >' % (
                self.base_url, urlencode(self.params))
        else:
            next_page = '<li><a href = "%s?%s" aria-label = "Next">下一页</span></a></li>' % (
                self.base_url, urlencode(self.params))
        page_html_list.append(next_page)

        # 尾页
        self.params['page'] = self.max_page_num
        last_page = '<li><a href="%s?%s">尾页</a></li>' % (self.base_url, urlencode(self.params),)
        page_html_list.append(last_page)

        return ''.join(page_html_list)

二、使用组件

#!usr/bin/env python
# -*- coding:utf-8 -*-
from flask import Flask,render_template,request,redirect
from pager import Pagination
from urllib.parse import urlencode
app = Flask(__name__)

# =========================django的用法=======================================
# pager_obj = Pagination(request.GET.get('page', 1), len(HOST_LIST), request.path_info, request.GET)
# host_list = HOST_LIST[pager_obj.start:pager_obj.end]
# html = pager_obj.page_html()
# return render(request, 'hosts.html', {'host_list': host_list, "page_html": html})

@app.route('/pager')
def pager():
    li = []
    for i in range(1,100):
        li.append(i)
    # print(li)
# ===================================flask的用法===============================
    pager_obj = Pagination(request.args.get("page",1),len(li),request.path,request.args,per_page_count=10)
    # print(request.args)
    index_list = li[pager_obj.start:pager_obj.end]
    html = pager_obj.page_html()
   return render_template("pager.html",index_list=index_list, html = html,condition=path)

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

三、html 模板代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width">
    <title>Title</title>
    <link rel="stylesheet" href="/static/bootstrap-3.3.7-dist/css/bootstrap.min.css">
    <style>
        .container {
            margin-top: 20px;
        }
    </style>
</head>
<body>
<div class="container">
    <a href="/add?{{ condition }}">
        <button class="btn btn-primary">添加</button>
    </a>
    <div class="row " style="margin-top: 10px">
        <table class="table table-bordered table-hover">
            <thead>
            <tr>
                <th>表头1</th>
                <th>表头2</th>
                <th>表头3</th>
                <th>表头4</th>
            </tr>
            </thead>
            <tbody>
            {% for foo in index_list %}
                <tr>
                    <td>{{ foo[0] }}</td>
                    <td>{{ foo[1] }}</td>
                    <td>{{ foo[2] }}</td>
                    <td>{{ foo[3] }}</td>
                </tr>
            {% endfor %}

            </tbody>
        </table>

        <nav aria-label="Page navigation" class="pull-right">
            <ul class="pagination">
                {{ html|safe }}
            </ul>
        </nav>
    </div>
</div>
</body>
</html>

四、flsak接口访问代码

#!/usr/bin/python
# -*- coding: utf-8 -*-

__author__ = 'mrs.wc'
__filename__ = 'demo'
__datetime__ = '2018/3/1 21:41'

import sys
reload(sys)
sys.setdefaultencoding('utf-8')


from flask import Flask, render_template, request, redirect
from page_tools import Pagination
from urllib import urlencode

app = Flask(__name__)


# =========================django的用法=======================================
# pager_obj = Pagination(request.GET.get('page', 1), len(HOST_LIST), request.path_info, request.GET)
# host_list = HOST_LIST[pager_obj.start:pager_obj.end]
# html = pager_obj.page_html()
# return render(request, 'hosts.html', {'host_list': host_list, "page_html": html})


# =========================flask的用法========================================
@app.route('/pager')
def pager():
    temp=('浙江大学','天津大学','北京大学','牛津大学')
    li = []
    for i in range(1, 1000000):
        li.append(temp)
    # print(li)
    pager_obj = Pagination(request.args.get("page", 1), len(li), request.path, request.args, per_page_count=15)
    print request.args
    print request.path
    index_list = li[pager_obj.start:pager_obj.end]
    html = pager_obj.page_html()  # request.path
    return render_template("pagers.html", index_list=index_list, html=html, condition=None)

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

五、个人实战项目

1. 个人问答平台

项目需要的的基础环境包配置:
安装方式：将需要安装的包保存在aa.txt中, cd到requirement.txt所在目录，运行：
pip批量安装package: $pip install -r requirement.txt pip批量卸载package:$ pip uninstall -r requirement.txt

alembic==0.9.8
aniso8601==2.0.0
astroid==1.6.0
backports-abc==0.5
backports.functools-lru-cache==1.4
backports.shutil-get-terminal-size==1.0.0
bleach==2.1.2
certifi==2017.11.5
click==6.7
colorama==0.3.9
configparser==3.5.0
cycler==0.10.0
decorator==4.1.2
Django==1.10.5
entrypoints==0.2.3
enum34==1.1.6
Flask==0.12.2
Flask-Migrate==2.1.1
Flask-RESTful==0.3.6
Flask-Script==2.0.6
Flask-SQLAlchemy==2.3.2
functools32==3.2.3.post2
html5lib==1.0.1
http==0.2
ipykernel==4.7.0
ipython==5.5.0
ipython-genutils==0.2.0
ipywidgets==7.1.0
isort==4.2.15
itsdangerous==0.24
Jinja2==2.10
jsonschema==2.6.0
jupyter-client==5.2.1
jupyter-core==4.4.0
lazy-object-proxy==1.3.1
Mako==1.0.7
MarkupSafe==1.0
matplotlib==2.1.1
mccabe==0.6.1
memory-profiler==0.52.0
mistune==0.8.3
MySQL-python==1.2.5
nbconvert==5.3.1
nbformat==4.4.0
notebook==5.2.2
numpy==1.14.0
pandocfilters==1.4.2
pathlib2==2.3.0
pickleshare==0.7.4
Pillow==5.0.0
prompt-toolkit==1.0.15
psutil==5.4.3
Pygments==2.2.0
pylint==1.8.1
pymssql==2.1.3
PyMySQL==0.8.0
pyparsing==2.2.0
pypiwin32==223
python-dateutil==2.6.1
python-editor==1.0.3
pytz==2017.3
pywin32==223
pyzmq==16.0.3
scandir==1.6
simplegeneric==0.8.1
singledispatch==3.4.0.3
six==1.11.0
SQLAlchemy==1.2.4
testpath==0.3.1
tornado==4.5.2
traitlets==4.3.2
wcwidth==0.1.7
webencodings==0.5.1
Werkzeug==0.12.2
widgetsnbextension==3.1.0
win-unicode-console==0.5
WMI==1.4.9
wrapt==1.10.11
xlrd==1.1.0

2. 数据库Models

#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""
@ __file_name__ = 'models.py'
@ __author__ = 'Empathy'
@ __time__   = '2017/9/24 21:28'
"""

from exits import db
from datetime import datetime


class User(db.Model):
    __tablename__ = 'user'
    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
    telphone = db.Column(db.String(11), nullable=False)
    username = db.Column(db.String(50), nullable=False)
    password = db.Column(db.String(10), 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)
    content = db.Column(db.Text, nullable=False)
    # 1.datetime.now()服务器运行的时间
    # 2.datetime.now，每次数据模型生成的时间
    create_time = db.Column(db.DateTime, default=datetime.now)
    author_id = db.Column(db.Integer, db.ForeignKey('user.id'))
    # 关联查询，反转查询
    author = db.relationship('User', backref=db.backref('questions'))


class Answer(db.Model):
    __tablename__ = 'answer'
    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
    content = db.Column(db.Text, nullable=False)
    create_time = db.Column(db.DateTime, default=datetime.now)
    # 1.关联外键,指定表名.主键字段
    question_id = db.Column(db.Integer, db.ForeignKey('question.id'))
    author_id = db.Column(db.Integer, db.ForeignKey('user.id'))
    # 2.反转查询，指定模型类名，反转对象名称
    question = db.relationship('Question', backref=db.backref('answers', order_by=id.desc()))
    author = db.relationship('User', backref=db.backref('answers'))

3. mysql 数据库的配置

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import os


# debug模式
DEBUG = True

# 24位随机cookia加密
SECRET_KEY =os.urandom(24)

# dialect+driver://username:password@host:port/database
# mysql数据库配置
DIALECT = 'mysql'
DRIVER = 'mysqldb'
USERNAME = 'xxx'
PASSWORD = 'xxxx'
HOST = '127.0.0.1'
PORT = '3306'
DATABASE = 'xxx'

DB_URI = "{}+{}://{}:{}@{}:{}/{}?charset=utf8".format(DIALECT, DRIVER, USERNAME, PASSWORD, HOST, PORT, DATABASE)
SQLALCHEMY_DATABASE_URI = DB_URI
SQLALCHEMY_TRACK_MODIFICATIONS = False

# DATA_BASE_INFO ={
#     'DIALECT': 'mysql',
#     'DRIVER': 'mysqldb',
#     'USERNAME': 'xxx',
#     'PASSWORD': 'xxx',
#     'HOST': '127.0.0.1',
#     'PORT': '3306',
#     'DATABASE': 'xxx',
#     'CHARSET': 'utf8'
# }

4. 用户登录校验装饰器

#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""
@ __file_name__ = 'decorators.py'
@ __author__ = 'Empathy'
@ __time__   = '2017/9/27 0:45'
"""

from functools import wraps
from flask import session,render_template,redirect,url_for

# 定义一个登录现在的装饰器
def login_require(func):
    @wraps(func)
    def wrapper(*args,**kwargs):
        if session.get('user_id'):
            return func(*args, **kwargs)
        else:
            return redirect(url_for('login'))
    return wrapper
# 高级函数-闭包，函数嵌套，返回返回对象本身

5. 数据库迁移管理

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
@ __file_name__ = 'manage.py'
@ __author__ = 'Empathy'
@ __time__   = '2017/9/24 21:29'
"""
# import sys
# reload(sys)
# sys.setdefaultencoding('utf-8')
from flask_script import Manager
from flask_migrate import Migrate,MigrateCommand
from zhiliao import app
from exits import db
from models import User,Question

# 使用manager绑定app
manager = Manager(app)
# 使用migrate绑定app和db
migrate = Migrate(app, db)

# 添加迁移数据库脚本命令道manager中
manager.add_command('db',MigrateCommand)
if __name__ == '__main__':
    manager.run()

6. Templates html模板核心代码

 <!--base 通用模板的代码-->
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>
        {% block title %}{% endblock %}-知了课堂问答平台
    </title>

<!-- 最新版本的 Bootstrap 核心 CSS 文件 -->
<link rel="stylesheet" href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
<!--cdn 加速 -->
<script sre="https://cdn.bootcss.com/jquery/3.2.1/jquery.js"></script>
<!-- 最新的 Bootstrap 核心 JavaScript 文件 -->
<script src="https://cdn.bootcss.com/bootstrap/3.3.7/js/bootstrap.min.js" integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa" crossorigin="anonymous"></script>
<!--自定义css样式-->
    <link rel="stylesheet" href="{{ url_for('static',filename='css/base.css') }}">
 {% block head %}{% endblock %}

</head>
<body>
<nav class="navbar navbar-default">
    <div class="container">
        <!-- Brand and toggle get grouped for better mobile display -->
        <div class="navbar-header">
            <button type="button" class="navbar-toggle collapsed" data-toggle="collapse"
                    data-target="#bs-example-navbar-collapse-1" aria-expanded="false">
                <span class="sr-only">Toggle navigation</span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
            </button>
            <!--log_img-->
            <a class="navbar-brand" href="">
                <img class="logo" src="{{url_for('static',filename='images/log.png')}}" alt="">
            </a>
        </div>
        <!-- Collect the nav links, forms, and other content for toggling -->
        <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
            <ul class="nav navbar-nav">
                <li class="/">
                    <a href="{{ url_for('index') }}">
                        首页 <span class="sr-only">(current)</span>
                    </a>
                </li>
                <li>
                    <a href="{{ url_for('question') }}">发布问答</a>
                </li>
            </ul>
            <!--form 提交表单get-方式提交关键词-->
            <form class="navbar-form navbar-left" action="{{ url_for('search') }}" method="get">
                <div class="form-group">
                    <input name="q" type="text" class="form-control" placeholder="请输入关键字">
                </div>
                <button type="submit" class="btn btn-default">搜索</button>
            </form>
            <ul class="nav navbar-nav navbar-right">
                {% if user %}
                    <li><a href="#"> {{ user.username }}</a></li>
                    <li><a href="{{ url_for('logout') }}"> 注销</a></li>
                {% else %}
                    <li><a href="{{ url_for('login') }}">登录</a></li>
                    <li><a href="{{ url_for('regist') }}">注册</a></li>
                {% endif %}
            </ul>
        </div>
    </div>
</nav>
<div class="main">
    {% block main %}{% endblock %}
</div>
</body>
</html>
  <!--index首页的代码-->
{% extends 'base.html' %}
{% block title %}首页{% endblock %}
{% block head %}
    <link rel="stylesheet" href="{{ url_for('static',filename='css/index.css') }}">
{% endblock %}
{% block main %}
    <ul>
    {% for question in  data_list %}
    <li>
            <div class="avatar-group">
                <img src="{{ url_for('static',filename='images/question.png')}}" alt="" class="avatar">
            </div>
            <div class="question-group">
                <p class="question-title">
                    <a href="{{ url_for('detail',question_id=question.id)}}">{{ question.title }}</a>
                </p>
                <p class="question-content">
                    {{ question.content }}
                </p>
                <div class="question-info">
                    <span class="question-author">{{ question.author.username }}</span>
                    <span class="question-time">{{ question.create_time }}</span>
                </div>
            </div>
        </li>
    {% endfor %}
    </ul>
    <!--分页的代码-->
    <nav aria-label="Page navigation" class="pull-right">
        <ul class="pagination">
            {{ html|safe }}
        </ul>
    </nav>
{% endblock %}

7.数据交互接口核心代码

#!/usr/bin/python
# -*- coding: utf-8 -*-

__author__ = 'mrs.wc'
__filename__ = 'page_tools'
__datetime__ = '2018/3/1 21:39'

# 导入Flask基本模块类
from flask import Flask,render_template,request,redirect,url_for,session,g
import config
from models import User,Question,Answer
from exits import db
import datetime
from decorators import login_require
from sqlalchemy import or_


# 初始化一个Flask对象
# Flask()
# 需要传递一个参数 __name__
# 1.方便框架去寻找资源
# 2. 方便flask 插件如flask SqlAlchemy 出错寻找错误位置

app = Flask(__name__)
app.config.from_object(config)
# 初始化app数据库
db.init_app(app)
from utils import page_utils

# @app.route()是一个装饰器
# @开头，在函数上面，表示装饰器
# 这个装饰器的作用：一个url和试图的映射关系


# web应用首页
@app.route('/')
def index():
    context ={
        'questions': Question.query.order_by('-create_time').all()
    }
    all_data_list=context.get('questions',[])
    data_list,html=page_utils.page_paginate(all_data_list,3)
    return render_template('index.html',data_list=data_list,html=html,condition=None)


# 登录功能模块，用户信息入库,保持cookie到session
@app.route('/login/', methods=['GET', 'POST'])
def login():
    if request.method=='GET':
        return render_template('login.html')
    else:
        telphone = request.form.get('telphone')
        password = request.form.get('password')
        user = User.query.filter(User.telphone == telphone, User.password == password).first()
        if user:
            # 保存用户session信息
            session['user_id']= user.id
            # 如果需要31天保持登录
            session.permanent = True
            # 跳转到首页
            return redirect(url_for('index'))
            # return u'{}:你好,您已经登录成功！;当前时间：{}'.format(user.username,datetime.datetime.now())
        else:
            # return u'手机号或者登录密码失败！'
            return render_template('loginerror.html')


# 注册功能模块，用户信息校验，入库
@app.route('/regist/', methods=['GET', 'POST'])
def regist():
    if request.method=='GET':
        return render_template('regist.html')
    else:
        telphone = request.form.get('telphone')
        username = request.form.get('username')
        password1 = request.form.get('password1')
        password2 = request.form.get('password2')
        #检验手机号，判断手机号是否注册
        user = User.query.filter(User.telphone==telphone).first()
        if user:
            return u'手机号已注册，请更换手机号！'
        # 密码校验,2次密码一样即可
        if password1!=password2:
            print password1,password2
            return u'两次密码不同，请核对再提交！'
        else:
            user = User(telphone=telphone,username=username,password=password1)
            db.session.add(user)
            db.session.commit()
            # 注册成功，跳转到登陆页面
            return redirect(url_for('login'))


# 注销功能模块 , 清除 session 中的user_id
@app.route('/logout/')
def logout():
    # session.pop('user_id')
    # del session['user_id']
    session.clear()
    return redirect(url_for('login'))


# 发布问答功能，数据入库
@app.route('/question/',methods=['GET', 'POST'])
@login_require # 装饰器放在函数下面才生效
def question():
    if request.method=="GET":
        return render_template('question.html')
    else:
        title = request.form.get('title')
        content = request.form.get('content')
        question = Question(title=title, content=content)
        # user_id = session.get('user_id')
        # user = User.query.filter(User.id == user_id).first()
        # question.author = user
        question.author = g.user
        db.session.add(question)
        db.session.commit()
        return redirect(url_for('index'))


# 问答详情页面，超链接跳转
@app.route('/detail/<question_id>/')
# @login_require
def detail(question_id):
    # return redirect(url_for('detail'))
    question_model= Question.query.filter(Question.id == question_id).first()
    all_data_list=list(question_model.answers)
    # question提供详细页面渲染使用
    answers, html = page_utils.page_paginate(all_data_list, 3) # all_data_list.content
    return render_template('detail.html',html=html, question=question_model,answers=answers)


# 发布评论，回答问题,限制只支持post提交
@app.route('/add_answer/', methods=['POST'])
@login_require
def add_answer():
    content = request.form.get('answer_content')
    question_id = request.form.get('question_id')
    answer = Answer(content=content)
    # user_id = session.get('user_id')
    # user = User.query.filter(User.id == user_id).first()
    # answer.author = user
    answer.author = g.user
    question = Question.query.filter(Question.id == question_id).first()
    answer.question = question
    db.session.add(answer)
    db.session.commit()
    # question提供详细页面渲染使用
    return redirect(url_for('detail', question_id=question_id))


# 页面关键字搜索功能模块
@app.route('/search/')
def search():
    q = request.args.get('q')
    if q and not q is None:
        condition = or_(Question.title.contains(q), Question.content.contains(q))
        questions = Question.query.filter(condition)
        all_data_list=list(questions)
        data_list, html = page_utils.page_paginate(all_data_list, 3)
        return render_template('index.html', html=html,data_list=data_list,condition=None)
    else:
        return render_template('index.html')
    # # 查询-与操作 # title, content
    # # questions = Question.query.filter(or_(Question.title.contains(q),\
    # # Question.content.contains(q))).order_by('-create_time')
    # # 查询-或操作 # title , content
    # # condition=or_(Question.title.contains(key),Question.content.contains(key))
    # condition = or_(Question.title.contains(q), Question.content.contains(q))
    # questions = Question.query.filter(condition)
    # # questions = Question.query.filter(condition)
    # # questions = questions.order_by('-create_time').first().title
    # # questions=questions 中第一个questions为models 中定义的关联表对象名称
    # return render_template('index.html', questions=questions)


"""
flask 中的g对象,存放对象，可以调用
"""
# 代码优化，g对象存取常用对象
@app.before_request
def my_before_request():
    user_id = session.get('user_id')
    if user_id:
        user = User.query.filter(User.id == user_id).first()
        if user:
            g.user=user


""" 钩子函数和视图函数，上下文处理函数 执行步骤： 
# 1.首先 before_request  -> views func() -> context_processor
# 2. 绑定user到g对象 ->views func() -> context_processor
"""
# 定义一个钩子函数，返回一个字典(变量可以供模板渲染)，没有也要返回一个空字典对象
@app.context_processor
def my_context_processor():
    if hasattr(g,'user'):
        return {'user': g.user}
    else:
        return {}


# 定义一个钩子函数，返回一个字典(变量可以供模板渲染)，没有也要返回一个空字典对象
# @app.context_processor
# def my_context_processor():
#     user_id = session.get( 'user_id' )
#     user = User.query.filter( User.id == user_id ).first( )
#     if user:
#         return {'user': user}
#     else:
#         return {}

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

六、参考

1. https://www.cnblogs.com/liluning/p/8297048.html
2. https://www.cnblogs.com/haiyan123/p/8228447.html