Flask-Session SQLAlchemy Script Migrate wtforms

Posted 2021-01-31 从入门到出门

tags:

篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了Flask-Session SQLAlchemy Script Migrate wtforms相关的知识，希望对你有一定的参考价值。

Flask-session

Flask-session跟框架自带的session有什么区别呢~

框架自带的session是通过请求上下文~放入到Local中的~那如果我们想把session放入别的地方怎么办呢~~

比如redis~或者数据库~等等~~Flask-session就提供了这些功能~~我们看下Flask-session怎么用~~

一、下载安装

pip install flask-session

二、导入并实例化

from flask_session import Session

from flask import  Flask

def create_app():
   app = Flask(__name__)
   app.config.from_object("settings.DevConfig")

   Session(app)
   app.register_blueprint(userBlue)
   return app

三、配置文件

class BaseConfig(object):
    # Flask-Session  第三步
    # SESSION_TYPE = \'redis\'
    # SESSION_REDIS = Redis(host=\'192.168.0.94\', port=\'6379\')

实现原理

回顾一下session的实现原理~请求进来先把request以及session封装到RequestContext对象中~~

然后调用push方法通过LocalStark放入到Local中~这时候放入到Local中的session还是空的~

然后调用了session_interface中的open_session 以及save_session方法~~

那我们再看下~~Flask-session都做了什么~~

修改了app.session_interface这个类~所以在我们调用open_session以及save_session的时候~调用的是我们配置的类里的方法~

从而实现了session存储地方的不同~

Flask SQLAlchemy

学习Flask-SQLAlchemy之前~大家要先学习一下SQLAlchemy~一个Python的ORM框架~~

点我学习SQLALchemy

接下来是Flask-SQLAlchemy的应用~~

一、下载安装

pip3 install flask-sqlalchemy

二、导入并实例化SQLAlchemy

# 在跟项目同名的文件夹下的 init.py中
from flask_sqlalchemy import SQLAlchemy
db = SQLAlchemy()

from .views.user import us

# !!! 注意事项
#   必须在导入蓝图之前

三、初始化

def create_app():
    app = Flask(__name__)
    app.config.from_object("settings.BaseConfig")

    app.register_blueprint(us)
    # Flask-Session 第二步实例化session
    Session(app)
    # 初始化db
    db.init_app(app)
    return app

四、在配置文件写入配置信息

class BaseConfig(object):
    # Flask-Session  第三步
    # SESSION_TYPE = \'redis\'
    # SESSION_REDIS = Redis(host=\'192.168.0.94\', port=\'6379\')

    SQLALCHEMY_DATABASE_URI = "mysql+pymysql://root:root1234@127.0.0.1:3306/code_record?charset=utf8"
    SQLALCHEMY_POOL_SIZE = 10
    SQLALCHEMY_MAX_OVERFLOW = 5

    # SQLALCHEMY_TRACK_MODIFICATIONS = False
    pass

五、创建model

# by gaoxin
from sqlalchemy import Column, Integer, String
from flask_demo import db


class Users(db.Model):
    __tablename__ = \'users\'

    id = Column(Integer, primary_key=True)
    name = Column(String(32), index=True, nullable=False)

六、生成表（需要使用app上下文）

# by gaoxin
from flask_demo import db, create_app
from flask_demo.models import *
# 一定要导入models 否则找不到表创建不出来
app = create_app()
app_ctx = app.app_context()

with app_ctx:
    db.create_all()
    # db.drop_all()

七、基于ORM对数据库操作

# by gaoxin
from flask import Blueprint
from flask_demo import db
from flask_demo.models import Users

us = Blueprint("us", __name__)


@us.route("/index")
def index():
    # db.session.add(Users(name="gaoxin"))
    # db.session.commit()
    # db.session.remove()
    ret = db.session.query(Users).all()
    print(ret)
    db.session.remove()
    return "Index"

Flask-Script

一、下载安装

pip3 install flask-script

二、增加的功能 runserver

# by gaoxin

from flask_demo import create_app
from flask_script import Manager

app = create_app()
manager = Manager(app)

if __name__ == \'__main__\':
    # app.run()
    manager.run()
# 启动命令变成
# python3 manager.py runserver -h 127.0.0.1 -p 8000
# Running on http://127.0.0.1:8000/ (Press CTRL+C to quit)

三、自定义命令

# by gaoxin

from flask_demo import create_app
from flask_script import Manager

app = create_app()
manager = Manager(app)


# 位置传参
@manager.command
def custom(arg):
    """
    自定义命令
    python manage.py custom 123
    :param arg:
    :return:
    """
    print(arg)
    
    
# 关键字传参
@manager.option(\'-n\', \'--name\', dest=\'name\')
@manager.option(\'-u\', \'--url\', dest=\'url\')
def cmd(name, url):
    """
    自定义命令
    执行： python manage.py  cmd -n gaoxin -u http://www.oldboyedu.com
    :param name:
    :param url:
    :return:
    """
    print(name, url)


if __name__ == \'__main__\':
    # app.run()
    manager.run()

Flask-migrate

一、下载安装

pip3 install flask-migrate

二、增加的命令

　　！！！！依赖flask-script ！！！！

原来数据库有表的话，会把原来多余的表删了。不能多表或者少表

# by gaoxin

from flask_demo import create_app, db
from flask_demo.models import *
from flask_script import Manager
from flask_migrate import Migrate, MigrateCommand

app = create_app()
manager = Manager(app)
Migrate(app, db)

"""
# 数据库迁移命名
# 依赖 flask-script
python manage.py db init # 初始化
python manage.py db migrate # makemigrations
python manage.py db upgrade # migrate
"""
manager.add_command("db", MigrateCommand)

if __name__ == \'__main__\':
    # app.run()
    manager.run()

wtforms

类比我们django的Form组件~

Form组件的主要应用是~帮助我们自动生成html，以及做表单数据的验证~~

用法跟Form组件大同小异~~

一、下载安装

pip3 install wtforms

二、自动生成HTML

第一步生成一个Form类

第二步实例化这个Form类，把这个实例化对象当成参数传递给前端

# 视图页面

from wtforms import Form, widgets, validators
from wtforms.fields import simple

class MyForm(Form):
    name = simple.StringField(
        label="用户名",
        render_kw={"placeholder": "请输入用户名"},
        widget=widgets.TextArea(),
        default="gaoxin"
    )
    pwd = simple.PasswordField()


@ac.route("/login", methods=["GET", "POST"])
def login():
    if request.method == "GET":
        form = MyForm(data={"name": "gao"})
        return render_template("login.html", form=form)

<!--html页面-->
<form action="" novalidate>
    用户名： {{form.name}}
    密码： {{form.pwd}}
    <button type="submit">提交</button>

</form>
<!--循环出来的页面-->
<form action="">
    {% for field in form %}
        {{field.label}}: {{field}}

    {% endfor %}
    <button type="submit">提交</button>

</form>

三、验证

第一步在Form类中增加验证信息

第二步在视图中做数据的校验并且页面展示错误信息

# 视图页面
class MyForm(Form):
    name = simple.StringField(
        label="用户名",
        render_kw={"placeholder": "请输入用户名"},
        # widget=widgets.TextArea(),
        validators=[
            validators.DataRequired(message="用户名不能为空"),
            validators.Length(min=6, max=18, message=\'用户名长度必须大于%(min)d且小于%(max)d\')
        ],
        # default="gaoxin"
    )
    pwd = simple.PasswordField(
        label="密码",
        widget=widgets.PasswordInput(),
        validators=[
            validators.DataRequired(message=\'密码不能为空.\'),
            validators.Length(min=8, message=\'用户名长度必须大于%(min)d\'),
            validators.Regexp(regex="^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d)(?=.*[$@$!%*?&])[A-Za-z\\d$@$!%*?&]{8,}",
                              message=\'密码至少8个字符，至少1个大写字母，1个小写字母，1个数字和1个特殊字符\')
        ]
    )


@ac.route("/login", methods=["GET", "POST"])
def login():
    if request.method == "GET":
        form = MyForm(data={"name": "gao"})
        return render_template("login.html", form=form)
    form = MyForm(formdata=request.form)
    if form.validate():
        print(form.data)
    else:
        return render_template("login.html", form=form)
    return "lakdsjlga"

<!--循环出来的页面-->
<form action="" method="post" novalidate>
    {% for field in form %}
        {{field.label}}: {{field}} {{field.errors[0]}}

    {% endfor %}
    <button type="submit">提交</button>

</form>

四、拓展字段

以用户注册为例，输入用户名，密码，重复密码，性别和爱好。

class RegisterForm(Form):
    name = simple.StringField(
        label=\'用户名\',
        validators=[
            validators.DataRequired()
        ],
        widget=widgets.TextInput(),
        # render_kw={\'class\': \'form-control\'},
        default=\'gaoxin\'
    )

    pwd = simple.PasswordField(
        label=\'密码\',
        validators=[
            validators.DataRequired(message=\'密码不能为空.\')
        ],
        widget=widgets.PasswordInput(),
        # render_kw={\'class\': \'form-control\'}
    )

    pwd_confirm = simple.PasswordField(
        label=\'重复密码\',
        validators=[
            validators.DataRequired(message=\'重复密码不能为空.\'),
            validators.EqualTo(\'pwd\', message="两次密码输入不一致")
        ],
        widget=widgets.PasswordInput(),
        render_kw={\'class\': \'form-control\'}
    )

    email = html5.EmailField(
        label=\'邮箱\',
        validators=[
            validators.DataRequired(message=\'邮箱不能为空.\'),
            validators.Email(message=\'邮箱格式错误\')
        ],
        widget=widgets.TextInput(input_type=\'email\'),
        render_kw={\'class\': \'form-control\'}
    )

    gender = core.RadioField(
        label=\'性别\',
        choices=(
            (1, \'男\'),
            (2, \'女\'),
        ),
        coerce=int
    )
    city = core.SelectField(
        label=\'城市\',
        choices=(
            (\'bj\', \'北京\'),
            (\'sh\', \'上海\'),
        )
    )

    hobby = core.SelectMultipleField(
        label=\'爱好\',
        choices=(
            (1, \'篮球\'),
            (2, \'足球\'),
        ),
        coerce=int
    )

    favor = core.SelectMultipleField(
        label=\'喜好\',
        choices=(
            (1, \'篮球\'),
            (2, \'足球\'),
        ),
        widget=widgets.ListWidget(prefix_label=False),
        option_widget=widgets.CheckboxInput(),
        coerce=int,
        default=[1, 2]
    )

    def __init__(self, *args, **kwargs):
        super(RegisterForm, self).__init__(*args, **kwargs)
        # 从数据库获取数据 做到实时更新
        self.favor.choices = ((1, \'篮球\'), (2, \'足球\'), (3, \'羽毛球\'))


@ac.route(\'/register\', methods=[\'GET\', \'POST\'])
def register():
    if request.method == \'GET\':
        form = RegisterForm(data={\'gender\': 1})
        return render_template(\'register.html\', form=form)
    else:
        form = RegisterForm(formdata=request.form)
        if form.validate():
            return "注册成功"
        else:
            print(form.errors)
            return render_template(\'register.html\', form=form)

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>用户注册</h1>
<form method="post" novalidate style="padding:0  50px">
    {% for item in form %}
    <p>{{item.label}}: {{item}} {{item.errors[0] }}</p>
    {% endfor %}
    <input type="submit" value="提交">
</form>
</body>
</html>