Flask-SQLAlchemy
MySQL是免费开源软件，大家可以自行搜索其官网（https://www.MySQL.com/downloads/）
测试MySQL是否安装成功
在所有程序中，找到MySQL→MySQL Server 5.6下面的命令行工具，然后单击输入密码后回车，就可以知道MySQL数据库是否链接成功。
右击桌面上的“计算机”，在弹出的快捷键菜单中选择“属性”｜“高级系统设置”｜“环境变量”，在path里面添加MySQL bin目录的路径。选择环境变量，在环境变量中的path路径下输入你的MySQL路径就行了。默认安装的路径是C:\MySQL\MySQL Server 5.6\bin
安装flask-sqlalchemy，安装不了就更换豆瓣源
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对象-关系映射实质
class Lib_card(db.Model):
__tablename__ = 'lib_card'
id = db.Column(db.Integer, primary_key=True, comment='id号')
card_id = db.Column(db.Integer, nullable=False, comment = '借书证')
book_id = db.Column(db.Integer, db.ForeignKey('book.id'))
books = db.relationship('Book', backref=db.backref('cards'),uselist=False)
在Flask-SQLAlchemy中，插入、修改、删除操作均由数据库会话管理
需要一个配置config.py
USERNAME= 'root' #设置登录账号
PASSWORD= '930103' #设置登录密码
HOST= '127.0.0.1' #设置主机地址
PORT= '3306' #设置端口号
DATABASE= 'demo1' #设置访问的数据库
SQLALCHEMY_DATABASE_URI= f'mysql+pymysql://{USERNAME}:{PASSWORD}@{HOST}:{PORT}/{DATABASE}'#创建数据库连接示例
#动态追踪修改设置，如未设置只会提示警告
SQLALCHEMY_TRACK_MODIFICATIONS=False
#查询时会显示原始SQL语句
SQLALCHEMY_ECHO= True
实例
from datetime import datetime
from flask import Flask #导入Flask模块
from flask_sqlalchemy import SQLAlchemy #导入SQLAlchemy模块
import config #导入配置文件
app= Flask(__name__) #Flask初始化
app.config.from_object(config) #配置文件实例化
#初始化一个对象
db=SQLAlchemy(app)
class Book(db.Model):
__tablename__ = 'book'
id = db.Column(db.Integer, primary_key = True,comment='id号')
title = db.Column(db.String(50), nullable=False,comment='书名')
publishing_office = db.Column(db.String(100), nullable=False,comment='出版社')
isbn = db.Column(db.String(100), nullable=False, comment='isbn号')
storage_time = db.Column(db.DateTime, default=datetime.now(), comment='入库时间')
class Lib_card(db.Model):
__tablename__ = 'lib_card'
id = db.Column(db.Integer, primary_key=True, comment='id号')
card_id = db.Column(db.Integer, nullable=False, comment = '借书证')
book_id = db.Column(db.Integer, db.ForeignKey('book.id'))
books = db.relationship('Book', backref=db.backref('cards'),uselist=False)
with app.app_context():
#测试数据库连接是否成功
db.create_all() #创建数据库
# book1= Book(id=9,title='智能导论', publishing_office='高等教育出版社',isbn='9787040479844')
# db.session.add(book1)
# db.session.commit()
# result = Book.query.filter(Book.id == 9).first()
# print(result.title)
# agine = Book.query.filter(Book.title == result.title).all()
# for i in agine:
# print(i.id)
# db.session.delete(result)
# db.session.commit()
# card1=Lib_card(card_id='18001', book_id='8')
# card2=Lib_card(card_id='18002', book_id='8')
# db.session.add(card1)
# db.session.add(card2)
# db.session.commit()
book_query = Book.query.filter(Book.id == 9).first()
lib_card_query = book_query.cards
for i in lib_card_query:
print(i.card_id)
@app.route('/')
def index():
return 'index'
# if __name__== '__main__':
# app.run(debug=True)
注意：一个表（模型）的定义必须要定义一个主键，这个主键一般为id。在定义了Lib_card类后，申明了一个外键，并且在relationship方法中使用uselist=False来约束其关系。book_id =db.Column(db.Integer,db.ForeignKey('book.id'))表示创建一个外键，类型要跟主表一样，通过db.ForeignKey("user.id")与主表绑定books =db.relationship('Book'，backref=db.backref('cards')；uselist=False)表示Book可以根据Lib_card中的借书证查找到book表中的信息,backref="cards"表示book表可以直接通过cards查找到该书下的借书证号码。
框架实例
建一个apps文件夹，添加一个admin包，admin包下创建三个py文件
#__init__.py #预加载模块内容 #其他地方调用的时候 可以直接from apps.admin import bp as admin_bp不用找到views from .views import bp
#forms.py
from flask_wtf import FlaskForm
from wtforms import *
from wtforms.validators import *
class NameForm(FlaskForm):
username = StringField('用户名',validators=[DataRequired()])
password = PasswordField('密码',validators=[DataRequired()])
submit = SubmitField('提交')
#models.py
from exts import db
class User(db.Model):
__tablename__ = 'jq_user'
uid = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String(50), nullable=False, comment="用户名")
password = db.Column(db.String(100), nullable=False,comment="密码")
email = db.Column(db.String(50), nullable=False, unique=True, comment = "邮箱")
#views.py
from flask import Blueprint, request, flash, render_template
from apps.admin.forms import NameForm
from apps.admin.models import User
bp = Blueprint("admin",__name__)
@bp.route("/admin",methods=['GET','POST'])
def index():
form = NameForm()
if request.method == 'POST':
if form.validate_on_submit():
username = request.form.get('username')
password = request.form.get('password')
result = User.query.filter(User.username==username).first()
if result and password == result.password:
flash('登录成功')
else:
return render_template('login.html', form=form, errormsg="登陆失败")
return render_template('login.html', form=form)
建一个文件夹templates，专门放login.html文件，通过render_template调用
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<h1>用户注册登录</h1>
<form method="post" action="/test/admin">
{{ form.csrf_token()}}
{{ form.username.label }}{{ form.username}}
{{ form.password.label }}{{ form.password}}
{{ form.submit }}{{errormsg}}
{% for message in get_flashed_messages() %}
{{ message }}
{% endfor %}
</form>
</head>
<body>
</body>
</html>
建一个app.py
from flask import Flask
from apps.admin import bp as admin_bp
from exts import db
from apps.common import bp as common_bp
from apps.front import bp as front_bp
from apps.admin.models import User
from apps.common.models import Book
def create_app():
app = Flask(__name__)
app.secret_key = '123321'
#注册蓝图,注册时候可以设置前缀
app.register_blueprint(admin_bp,url_prefix="/test")
app.register_blueprint(common_bp)
app.register_blueprint(front_bp)
app.config.from_object('config')
# db.app = app
db.init_app(app)
return app
if __name__ == '__main__':
app = create_app()
with app.app_context():
db.create_all()
app.run(host="127.0.0.1",port=1314,debug=True)
建一个config.py
DEBUG=True
USERNAME= 'root' #设置登录账号
PASSWORD= '930103' #设置登录密码
HOST= '127.0.0.1' #设置主机地址
PORT= '3306' #设置端口号
DATABASE= 'demo1' #设置访问的数据库
SQLALCHEMY_DATABASE_URI= f'mysql+pymysql://{USERNAME}:{PASSWORD}@{HOST}:{PORT}/{DATABASE}'#创建数据库连接示例
#动态追踪修改设置，如未设置只会提示警告
SQLALCHEMY_TRACK_MODIFICATIONS=False
#查询时会显示原始SQL语句
SQLALCHEMY_ECHO= True
建一个exts.py
#encoding:utf-8 from flask_sqlalchemy import SQLAlchemy db=SQLAlchemy()
