python flask mysql 教程

最新推荐文章于 2025-12-10 21:28:18 发布

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#python #flask #mysql

本文详细展示了如何用PythonFlask和SQLAlchemy实现一个基础的API，包括模型定义、查询、添加、更新和删除操作，以及数据库迁移的过程。

废话补多少直接上代码from flask import Flask, request

from flask_sqlalchemy import SQLAlchemyfrom flask_migrate import Migratefrom datetime import datetimefrom waymon import res# post request.form.get("")# get  request.args.get("")
app = Flask(__name__)app.config["SQLALCHEMY_DATABASE_URI"] = "mysql+pymysql://root:123456@127.0.0.1:3306/test"# 追踪数据库 一般不开启app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False
db = SQLAlchemy(app)

class Todo(db.Model):    id = db.Column(db.Integer, primary_key=True)    content = db.Column(db.String(200), nullable=False)    completed = db.Column(db.Integer, default=0)    pub_date = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
    def __repr__(self):        return "<Task %r>" % self.id

migrate = Migrate(app=app, db=db)

@app.route("/info", methods=["GET"])def info():    id = request.args.get("id")    task = Todo.query.filter(Todo.id == id).first()    return res(task, "ok", 0)

@app.route("/list", methods=['GET'])def list():    page = request.args.get("page")    print(page)    size = request.args.get("size")    print(size)    tasks = Todo.query.order_by(Todo.pub_date).all()    return res(tasks, "ok", 0)

@app.route("/add", methods=["POST", "GET"])def add():    if request.method == "POST":        task_content = request.form.get("content")        new_task = Todo(content=task_content)        try:            db.session.add(new_task)            db.session.commit()            return res(None, "ok", 0)        except:            return res(None, "err", 1)    else:        task_content = request.args.get("content")        new_task = Todo(content=task_content)        try:            db.session.add(new_task)            db.session.commit()            return res(None, "ok", 0)        except:            return res(None, "err", 1)

@app.route("/update/<int:id>", methods=["POST"])def update(id):    task = Todo.query.get_or_404(id)    if request.method == "POST":        task.content = request.form["task"]        try:            db.session.commit()            return res(None, "ok", 0)        except:            return res(None, "ok", 1)    else:        return res(None, "不支持GET", 2)

@app.route("/delete/<int:id>", methods=["POST"])def delete(id):    task = Todo.query.get_or_404(id)    try:        db.session.delete(task)        db.session.commit()        return res(data=None, msg="ok", status=0)    except:        return res(None, "err", 1)

if __name__ == '__main__':    app.run(port=5000)

json&get&post 返回值封装

from flask import jsonifyfrom sqlalchemy.orm import DeclarativeMetaimport requestsimport json

def res(data=None, msg="ok", status=0):    """        json 返回值    """    response = {        "data": data,        "msg": msg,        "status": status    }    try:        response['data'] = serializer(data)        return jsonify(response)    except SerializationError as e:        response['status'] = e.code        response['msg'] = e.message        return jsonify(response)

def serializer(obj):    """    将对象转换为可以序列化为JSON的数据类型    """    if obj is None:        return None    try:        # 如果对象本身就是可以序列化为JSON的类型，则直接返回        if isinstance(obj, (str, int, float, bool, list, tuple, dict)):            return obj        # 如果对象是ORM对象，则将其转换为字典并返回        elif isinstance(obj.__class__, DeclarativeMeta):            return {c.name: getattr(obj, c.name) for c in obj.__table__.columns}        # 如果对象实现了__dict__方法，则将其转换为字典并返回        elif hasattr(obj, '__dict__'):            return obj.__dict__        else:            raise SerializationError(code=500, message="Cannot serializer obj")    except Exception as e:        raise SerializationError(code=500, message=str(e))

class SerializationError(Exception):    """       自定义的异常类，用于处理序列化错误    """    def __init__(self, code, message):        self.code = code        self.message = message

def get(uri, params):    """       get 请求    """    response = requests.get(uri, data=params)    if response.status_code == 200:        result = json.loads(response.content)        return result    else:        return res(None, response.text, response.status_code)

def post(uri, data):    """        post 请求    """    response = requests.post(uri, json=data)    if response.status_code == 200:        result = json.loads(response.content)        return result    else:        return res(None, response.text, response.status_code)

三：基础组件

python3.11 -m pip install flask
python3.11 -m pip install SQLalchemy
python3.11 -m pip install flask-sqlalchemy
python3.11 -m pip install flask-migrate

四：数据库迁移

1). 创建迁移仓库(migrations目录)python3.11 app.py  db init2). 读取类的内容, 生成版本文件, 并没有真正在数据库中添加或删除;python3.11  app.py  db migrate -m "版本名后缀"13). 在数据库中增删改, 也就是将迁移应用于数据库;python3.11 app.py  db upgrade————————————————

五: SQLAlchemy orm 简单的使用

1 创建表class Todo(db.Model):    id = db.Column(db.Integer, primary_key=True)    content = db.Column(db.String(200), nullable=False)    completed = db.Column(db.Integer, default=0)    pub_date = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
    def __repr__(self):        return "<Task %r>" % self.id       
  2 单条查询  Todo.query.filter(Todo.id == id).first()  3 多条查询  Todo.query.order_by(Todo.pub_date).all()  3  添加  db.session.add(new_task)  4 修改    task.content = request.form["task"]  db.session.commit()  5 删除