flask_sqlalchemy 简单实用

来自网易云课堂的知了课堂
1.)增删改查
config.py

# -*- coding:utf8 -*-



import os
basedir = os.path.abspath(os.path.dirname(__file__))
#print(basedir) #E:\Web\tonghuashun\stock\app
class Config:
    # mysql_conf = dict(
    #     host = '127.0.0.1',
    #     database = 'tonghuashun',
    #     user = 'root',
    #     password = '297002372as',
    #     port = 3306,
    #     charset = "utf8")
    # mysqlurl = "mysql://root:[email protected]/tonghuashun?charset=utf8"

    @staticmethod
    def init_app(app):
        pass

    SECRET_KEY = os.environ.get("SECRET_KEY") or 'you guess and guess'

class DevelopmentConfig(Config):
    DEBUG= True
    MAIL_SERVER = "[email protected]"
    SQLALCHEMY_DATABASE_URI = "mysql+pymysql://root:[email protected]:3306/tonghuashun?charset=utf8"
    SQLALCHEMY_TRACK_MODIFICATIONS= False


config = {
    "defalut":DevelopmentConfig
}
#固定名 SQLALCHEMY_DATABASE_URI

run.py

from flask import Flask,render_template,redirect,url_for
from flask_sqlalchemy import SQLAlchemy
from config import config

app = Flask(__name__)
app.config.from_object(config["defalut"])
db = SQLAlchemy(app)

#
# 创建article表
# create table article(
#     id int primary ke autoincrement,
#     title varchar(100) not null,
#     content text not null,
# )
class Article(db.Model):
    __tablename__ = 'article'
    id = db.Column(db.Integer,primary_key=True,autoincrement=True)
    title = db.Column(db.String(100),nullable=False)   #varchar和char都是对应db.String
    contenet = db.Column(db.Text,nullable=False)
#
# db.create_all() #创建模型，创建表。

@app.route("/index")
def hell():
    #增
    #1.新建一个实例。
    #2.使用add
    #3.提交
    # article_1 = Article(title="aaa",contenet="bbb")
    # db.session.add(article_1)
    # #做了一层事务操作,所以要提交。
    # db.session.commit()


    #查
    #result = Article.query.filter(Article.title=="aaa").first()
    #Article.query.filter(Article.title=="aaa")的返回是一个Query对象，
    # 如果取第一个数据，就使用result.first()
    #print(result) #[<Article 1>]返回一个Article的数据的数组。
    #print(result.title)
    #print(result.contenet)
    """
    [<Article 1>]
    aaa
    bbb
    """

    #改
    #1.先把你要更改的数据查找出来。
    #2.吧这条数据，需要修改的地方进行修改
    #3.事务提交
    # article_1 = Article.query.filter(Article.title=="aaa").first()
    # article_1.title = 'new title'
    # db.session.commit()

    #删
    #1.先把删除的数据查找出来
    #2.吧这条数据删除掉
    #3.做事务提交
    #article_1 = Article.query.filter(Article.title == "new title").first()
    #db.session.delete(article_1)
    #db.session.commit()

    return render_template("index.html")


@app.route("/lg")
def login():
   return render_template("login.html")

@app.route("/base")
def test():
    return render_template("base.html")


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

2.外键约束：
不合理的：

from flask import Flask,render_template,redirect,url_for
from flask_sqlalchemy import SQLAlchemy
from config import config

app = Flask(__name__)
app.config.from_object(config["defalut"])
db = SQLAlchemy(app)

# 用户表
# create table users(id int primary key autoincrement,
#                     username varchar(100) not null
# )
#
# 文章表：
#     create table article (
#         id int primary key autoincrement,
#         title varchar(100) not null,
#         content text not null,
#         author_id int,
#         foreign key `author_id` references `users.id`
# )

class User(db.Model):
    __tablename__ = "users"
    id = db.Column(db.Integer,primary_key=True,autoincrement=True)
    username = db.Column(db.String(100),nullable=False)



class Article(db.Model):
    __tablename__ = 'article'
    id = db.Column(db.Integer,primary_key=True,autoincrement=True)
    title = db.Column(db.String(100),nullable=False)
    contenet = db.Column(db.Text,nullable=False)
    author_id = db.Column(db.Integer,db.ForeignKey("users.id"))  #需要这一条

#db.create_all()
@app.route("/index")
def hell():

    # user_1 = User(username="zk")
    # db.session.add(user_1)
    # db.session.commit()


    # article_1 = Article(title='aaa',contenet='bbb',author_id=1)
    # db.session.add(article_1)
    # db.session.commit()

    article = Article.query.filter(Article.title =="aaa").first()
    authid = article.author_id
    user = User.query.filter(User.id ==authid).first()#需要修改的地方
    print(user.username)

    return render_template("index.html")


@app.route("/lg")
def login():
   return render_template("login.html")

@app.route("/base")
def test():
    return render_template("base.html")


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

另外一种：

from flask import Flask,render_template,redirect,url_for
from flask_sqlalchemy import SQLAlchemy
from config import config

app = Flask(__name__)
app.config.from_object(config["defalut"])
db = SQLAlchemy(app)

# 用户表
# create table users(id int primary key autoincrement,
#                     username varchar(100) not null
# )
#
# 文章表：
#     create table article (
#         id int primary key autoincrement,
#         title varchar(100) not null,
#         content text not null,
#         author_id int,
#         foreign key `author_id` references `users.id`
# )

class User(db.Model):
    __tablename__ = "users"
    id = db.Column(db.Integer,primary_key=True,autoincrement=True)
    username = db.Column(db.String(100),nullable=False)



class Article(db.Model):
    __tablename__ = 'article'
    id = db.Column(db.Integer,primary_key=True,autoincrement=True)
    title = db.Column(db.String(100),nullable=False)
    contenet = db.Column(db.Text,nullable=False)
    author_id = db.Column(db.Integer,db.ForeignKey("users.id"))
    author = db.relationship('User',backref=db.backref("article")) #backref反向引用

#db.create_all()
@app.route("/index")
def hell():
    article = Article.query.filter(Article.title == "aaa").first()
    username = article.author.username

    print(username)

    return render_template("index.html")


@app.route("/lg")
def login():
   return render_template("login.html")

@app.route("/base")
def test():
    return render_template("base.html")


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

3。查找数据

from flask import Flask,render_template,redirect,url_for
from flask_sqlalchemy import SQLAlchemy
from config import config

app = Flask(__name__)
app.config.from_object(config["defalut"])
db = SQLAlchemy(app)

# 用户表
# create table users(id int primary key autoincrement,
#                     username varchar(100) not null
# )
#
# 文章表：
#     create table article (
#         id int primary key autoincrement,
#         title varchar(100) not null,
#         content text not null,
#         author_id int,
#         foreign key `author_id` references `users.id`
# )

class User(db.Model):
    __tablename__ = "users"
    id = db.Column(db.Integer,primary_key=True,autoincrement=True)
    username = db.Column(db.String(100),nullable=False)



class Article(db.Model):
    __tablename__ = 'article'
    id = db.Column(db.Integer,primary_key=True,autoincrement=True)
    title = db.Column(db.String(100),nullable=False)
    contenet = db.Column(db.Text,nullable=False)
    author_id = db.Column(db.Integer,db.ForeignKey("users.id"))
    author = db.relationship('User',backref=db.backref("article")) #backref反向引用

#db.create_all()
@app.route("/index")
def hell():
    # article = Article(title="111",contenet="2222",author_id=1)
    # db.session.add(article)
    # db.session.commit()
    # username = article.author.username
    user = User.query.filter(User.username=='zk').first()
    result = user.article
    print(result)
    for x in result:
        print(x.title)

    return render_template("index.html")


@app.route("/lg")
def login():
   return render_template("login.html")

@app.route("/base")
def test():
    return render_template("base.html")


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