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flask框架初学-06-对数据库的增删改查

2022-08-04 01:30:00 【流墨馨】

上一节学习了怎么在flask中连接数据库，使得flask中的模型类可以与数据库中的表和字段一一映射。本节将具体介绍如果通过对模型对象进行操作，从而实现对数据库进行操作。

小知识点：
    CDN：内容分发网络，构建在现有网络基础之上的智能虚拟网络，依靠部署在各地的边缘服务器，通过中心平台的负载均衡'内容分发'、调度等功能模块，使用户就近截取		 所需内容，调高用户访问响应速度和命中率

一、查询

1、模型类.query.filter_by 简单查询

查询模型类操作对应数据库语句
查询所有模型类.query.allselect * from user;
查询一个模型类.query.get()
有条件的查询模型类.query.filter_by(字段名 = 值)select * from user where 字段名=值
模型类.query.filter_by(字段名 = 值).firdst()select * from user where 字段名=值 limit 0,1

除了模型类.query.filter_by()，还有一种模型类.query.filter()的查询方式，两者不同的地方在于：

  • 模型类.query.filter() 里面是一个布尔的条件 模型类.query.filter(模型名.字段名 == 值)
  • 模型类.query.filter_by() 里面是一个等值 模型类.query.filter_by(字段名 = 值)

2、模型类.query.filter()

简单查询

查询模型类操作对应数据库语句
查询所有，返回一个列表模型类.query.filter.all()select * from user;
查询所有结果的第一个，返回一个对象模型类.query.filter.first()select * from user where 字段名=值

模糊查询

查询模型类操作对应数据库语句
查询User中以t结尾的数据User.query.filter(User.username.endswith(‘t’)).all()select * from User where username like ‘%t’;
查询User中以t开头的数据User.query.filter(User.username.startswith(‘t’)).all()select * from User where username like ‘t%’;
查询User中包含t的数据User.query.filter(User.username.contains(‘t’)).all()select * from User where username like ‘%t%’;
查询User中包含t的数据User.query.filter(User.username.like(‘%t%’)).all()select * from User where username like ‘%t%’;

多条件判断查询 ：需要先导入sqlalchemy

from sqlalchemy import or_, and_, not_, __gt__,__lt__,__ge__(gt equal),__le__(le equal)
查询模型类操作对应数据库语句
查询User中username以t结尾或者包含i的所有数据User.query.filter(or_(User.username.like(‘t%’),User.username.contains(‘i’))).all()select * from User where username like ‘%t’ or username like '%i%;
查询User中username包含i并且rdatetine>2021-12-15 00:00:00的所有数据User.query.filter(and_(User.rdatetime. __ gt __ (‘2021-12-15 00:00:00’), User.username.contains(‘i’))).all()select * from User where username like '%i% and rdatetime>‘2021-12-15 00:00:00’;
查询User中phone为18176641567的所有数据User.query.filter(User.phone.in_([‘18176641567’,‘’,‘’])).all()seslect * from User where phone in (‘18179641567’,‘’,‘’);
如果要检索的字段是字符串 （varchar, db.String） ：
        User.username.startswith('')
        User.username.endswith('')
        User.username.contains('')
        User.username.like('')
        User.username.in_(['','',''])
        User.username == 'zzz'
如果要检索的字段是整型或者日期：
        User,age.__lt__(18)
        User.rdatetime.__gt__('')
        User.age.__le__(18)
        User.age.__ge__(18)
        User.age.between(15,30)
如果多个条件一起检索：
        and_
        or_
        not_

排序 ：order_by

查询模型类操作对应数据库语句
查询User中所有数据并进行倒序返回User.query.order_by(-User.id).all()select * from user desc;
查询User中包含i的所有数据并根据rdatetime正序返回User.query.filter(User.username.contains(‘i’)).order_by(‘rdatetime’).all()select * from user where username like '%i% order by rdatetime;
查询User中包含i的所有数据并根据rdatetime倒序返回User.query.filter(User.username.contains(‘i’)).order_by(-User.rdatetime).all()select * from user where username like '%i% order by rdatetime desc;

限制：limit

查询模型类操作对应数据库语句
查询User中根据id正序的前两条数据User.query.order_by(‘id’).limit(2).all()select * from User order by id limit 2;
跳过前两条记录再获取User中的两条记录User.query.offset(2).limit(2).all()select * from User order by id limit 2,4 ;

二、删除

1、逻辑删除（定义数据库中的表的时候，添加一个字段isdelete,通过此字段控制是否删除)

id = request.args.get('id')
user = User.query.get(id)
user.isdelete = True
db.session.commit()

2、物理删除

id = request.args.get('id')
user = User.query.get(id)
db.session.delete(user)
db.session.commit()

三、更新

id = request.args.get('id')
username = request.args.get('username')
phone = request.args.get('phone')
user = User.query.get(id)
user.phone = phone
user.username = username
db.session.commit()

四、添加

user = User()
user.xxx = xxx
db.session.add(user)
db.session.commit()

五、Example

项目结构

在这里插入图片描述

settings.py

class Config:
    DEBUG = True
    SQLALCHEMY_DATABASE_URI = 'mysql://root:[email protected]:3306/flaskday06'
    SQLALCHEMY_TRACK_MODIFICATIONS = True
    SQLALCHEMY_ECHO = True


class DevelopmentConfig(Config):
    ENV = 'development'
    DEBUG = True

class ProductionConfig(Config):
    ENV = 'production'
    DEBUG = True

apps下的__ init __.py

from flask import Flask

import settings
from apps.user.view import user_bp
from ext import db


def create_app():
    app = Flask(__name__,template_folder='../templates',static_folder='../static')
    app.config.from_object(settings.DevelopmentConfig)
    # 初始化db
    db.init_app(app)
    app.register_blueprint(user_bp)

    return app

ext下的__ init __.py

from flask_sqlalchemy import SQLAlchemy
import pymysql
pymysql.install_as_MySQLdb()

db = SQLAlchemy()

app.py

from flask_migrate import Migrate, MigrateCommand
from flask_script import Manager
from apps.user.models import User

from apps import create_app
from ext import db

app = create_app()
manager = Manager(app = app)

migrate = Migrate(app = app, db = db)
manager.add_command('db',MigrateCommand)

@manager.command
def init():
    print('初始化')

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

models.py

from datetime import datetime

from ext import db


class User(db.Model):
    id = db.Column(db.Integer,primary_key = True,autoincrement = True)
    username = db.Column(db.String(15),unique=True,nullable=False)
    password = db.Column(db.String(64),nullable=False)
    phone = db.Column(db.String(11),nullable=False,unique= True)
    isdelete = db.Column(db.Boolean,default=False)
    rdatetime = db.Column(db.DateTime,default = datetime.now())

    def __str__(self):
        return self.username

view.py

import hashlib

from flask import Blueprint, request, render_template, url_for
from sqlalchemy import or_, and_, not_
from werkzeug.utils import redirect

from apps.user.models import User
from ext import db

user_bp = Blueprint('user',__name__)

# 注册
@user_bp.route('/register',methods=['POST','GET'])
def register():
    if request.method == 'POST':
        username = request.form.get('username')
        password = request.form.get('password')
        repassword = request.form.get('repassword')
        phone = request.form.get('phone')
        if password == repassword:
            user = User()
            user.username = username
            user.password = hashlib.md5(password.encode('utf-8')).hexdigest()
            user.phone = phone
            db.session.add(user)
            db.session.commit()
            return redirect(url_for('user.user_center'))
        return render_template('user/register.html',msg='用户确认密码不正确！')
    return render_template('user/register.html')

# 用户中心
@user_bp.route('/')
def user_center():
    users = User.query.filter(User.isdelete == False).all()
    return render_template('user/center.html',users = users)

# 登录
@user_bp.route('/login')
def login():
    if request.method == 'POST':
        username = request.form.get('username')
        password = request.form.get('password')
        new_password = hashlib.md5(password.encode('utf-8')).hexdigest()
        user_list = User.query.filter_by(username=username)
        print(user_list)
        for u in user_list:
            if u.password == new_password:
                return '用户登录成功！'
            else:
                return render_template('user/login.html',msg='用户名或密码有误！')
            print(u)
        return 'testing'


    return render_template('user/login.html')

# 检索
@user_bp.route('/search')
def search():
    keyword = request.args.get('search')
    # 查询
    user_list = User.query.filter(or_(User.username.contains(keyword),User.phone.contains(keyword)))
    return render_template('user/center.html',users=user_list)

# 删除
@user_bp.route('/delete',endpoint='delete')
def user_delete():
    id = request.args.get('id')
    # 获取该id的用户
    user = User.query.get(id)
    # 1、逻辑删除
    user.isdelete = True
    """ # 2、物理删除 db.session.delete(user) """
    # 提交
    db.session.commit()
    return redirect(url_for('user.user_center'))

# 更新
@user_bp.route('/update',endpoint='update',methods=['GET','POST'])
def user_update():
    if request.method == 'POST':
        id = request.form.get('id')
        username = request.form.get('username')
        phone = request.form.get('phone')
        user = User.query.get(id)
        user.phone = phone
        user.username = username
        db.session.commit()
        return redirect(url_for('user.user_center'))

    else:
        id = request.args.get('id')
        user = User.query.get(id)
        return render_template('user/update.html',user=user)

@user_bp.route('/test')
def test():
    username = request.args.get('username')
    user = User.query.filter_by(username=username).first()
    print(user.username,user.rdatatime)

    user = User.query.filter_by(username=username).last()
    print(user.username, user.rdatatime)
    return 'test'

@user_bp.route('/select')
def user_select():
    # 根据主键查询用户
    user = User.query.get(1)
    user1 = User.query.filter(User.username == 'tom').all()
    user2 = User.query.filter(User.username == 'tom').first()
    # 相当于 select * from User where username like 't%';
    user_list = User.query.filter(User.username.startswith('t')).all()
    user_list2 = User.query.filter(User.username.like('%t%')).all()
    user_list3 = User.query.filter(or_(User.username.like('t%'), User.username.contains('i'))).all()
    user_list4 = User.query.filter(and_(User.rdatetime>'2021-12-15 00:00:00', User.username.contains('i'))).all()
    user_list5= User.query.filter(and_(User.rdatetime.__gt__('2021-12-15 00:00:00'), User.username.contains('i'))).all()
    user_list6 = User.query.filter(not_(User.username.contains('i'))).all()
    user_list7 = User.query.filter(User.phone.in_(['18179641567','',''])).all()
    user_list8= User.query.filter(User.rdatetime.between('2021-12-05 00:00:00','2021-12-15 23:00:00')).all()
    user_list9 = User.query.order_by(-User.id).all()
    user_list10 = User.query.filter(User.username.contains('i')).order_by('rdatetime').all()
    user_list11 = User.query.filter(User.username.contains('i')).order_by(-User.rdatetime).all()
    # limit的使用 + offset偏移
    user_list12 = User.query.order_by('id').limit(2).all()
    usee_list13 = User.query.offset(1).limit(2).all()

    return render_template('user/select.html',user=user,user1=user1,user2=user2,user_list=user_list,
                           user_list2=user_list2,user_list3=user_list3,user_list4=user_list4,user_list5=user_list5,
                           user_list6=user_list6,user_list7=user_list7,user_list8=user_list8,user_list9=user_list9,
                           user_list10=user_list10,user_list11=user_list11,user_list12=user_list12,usee_list13=usee_list13)

center.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>用户中心</title>
    <script crossorigin="anonymous" integrity="sha384-nrOSfDHtoPMzJHjVTdCopGqIqeYETSXhZDFyniQ8ZHcVy08QesyHcnOUpMpqnmWq" src="https://lib.baomitu.com/jquery/3.1.0/jquery.min.js"></script>

</head>
<body>
<div><a href="{
     { url_for('user.register') }}">注册</a>  <a href="{
     { url_for('user.login') }}">登录</a> <a href="">退出</a> </div>

<div>
  <h1>所有用户信息如下：</h1>
  搜索： <input type="text" name="search" placeholder="输入用户名或手机号码"><input type="button" value="搜索" id="search">
  <br>
  {% if users %}
    <table border="1" cellspacing="0" width="50%" >
      <tr>
        <td>序号</td>
        <td>用户名</td>
        <td>电话</td>
        <td>注册时间</td>
        <td>操作</td>
      </tr>
      {% for user in users %}
        <tr>
          <td>{
   { loop.index }}</td>
          <td>{
   { user.username }}</td>
          <td>{
   { user.phone }}</td>
          <td>{
   { user.rdatetime }}</td>
          <td>
            <a href="{
     { url_for('user.update') }}?id={
     { user.id }}">更新</a>
            <a href="{
     { url_for('user.delete') }}?id={
     { user.id }}">删除</a>
          </td>
        </tr>
      {% endfor %}

    </table>
  {% else %}
    <p style="color:red; font-size: 20px;">当前还没有任何用户，抓紧时间注册吧！！！</p>
  {% endif %}
</div>

<script> $('#search').click(function(){
       let content = $("input[name='search']").val(); <!-- alert(content);--> location.href = '{
      { url_for('user.search') }}?search='+content }) </script>
</body>
</html>

register.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>注册</title>
</head>
<body>
<h1>用户注册</h1>
<form action='{
     { url_for("user.register") }}' method="POST">
  <input type="text" name="username" placeholder="用户名"><br>
  <input type="password" name="password" placeholder="密码"><br>
  <input type="password" name="repassword" placeholder="确认密码"><br>
  <input type="text" name="phone" placeholder="手机号码"><br>
  <input type="submit" value="用户注册" >

</form>

</body>
</html>

login.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>登录</title>
</head>
<body>
<h1>用户登录</h1>
<p style="color:red">{
   { msg }}</p>
<form action='{
     { url_for("user.login") }}' method="POST">
  <input type="text" name="username" placeholder="用户名"><br>
  <input type="password" name="password" placeholder="密码"><br>
  <input type="submit" value="用户登录" >

</form>

</body>
</html>

select.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
user-----{
   { user }}------{
   { user.username }}-------{
   { user.rdatetime }}
<br>
user1----{
   { user1 }}
<br>
user2-----{
   { user2 }}
<br>
user_list----{
   { user_list | length }}
<br>
user_list2-----{
   { user_list2 | length }}
<br>
user_list3-----{
   { user_list3 | length }}
<br>
user_list4-----{
   { user_list4 | length }}
<br>
user_list5-----{
   { user_list5 | length }}
<br>
user_list6------{
   { user_list6 | length }}
<br>
user_list7------{
   { user_list7 | length }}
<br>
user_list8------{
   { user_list8 | length }}
<br>
user_list9------{
   { user_list9 | length }}
<br>
user_list10-----{
   { user_list10 | length }}
<br>
user_list11------{
   { user_list11 | length }}
<br>
user_list12------{
   { user_list12 | length }}
<br>
user_list13------{
   { user_list13 | length }}
<br>
</body>
</html>

update.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>用户更新</title>
</head>
<body>
<h1>用户更新操作</h1>
<form action="{
     {url_for('user.update')}}" method="post">
    <input type="hidden" name="id" value="{
     { user.id }}">
  <p><input type="text" name="username" value="{
     { user.username}}"> </p>
  <p><input type="text" name="phone" value="{
     { user.phone}}"> </p>
  <p><input type="submit" value="更新用户"> </p>

</form>

</body>
</html>

终端运行

python app.py runserver

运行结果

在这里插入图片描述

在这里插入图片描述

原网站

版权声明
本文为[流墨馨]所创，转载请带上原文链接，感谢
https://blog.csdn.net/weixin_42724501/article/details/126041978

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