Flask
分类:
IT文章
•
2023-12-04 09:50:31
一、基本使用
安装:
基本使用:
from flask import Flask, request, render_template, redirect, session
app = Flask(__name__, template_folder="templates", static_folder="static")
app.secret_key = "abc"
@app.route("/login", methods=["GET", "POST"])
def login():
if request.method == "GET":
return render_template("login.html")
username = request.form.get("username") # 如果是get请求 request.args
password = request.form.get("password")
if username == "pd" and password == "123":
session["user"] = username
return redirect("/index")
# return render_template("login.html", error="用户名或密码错误")
return render_template("login.html", **{"error": "用户名或密码错误"})
@app.route("/index")
def index():
user = session.get("user")
if not user:
return redirect("/login")
return render_template("index.html")
if __name__ == "__main__":
app.run()
二、配置文件
flask中的配置文件是一个flask.config.Config对象(继承字典),默认配置为:
{
'DEBUG': False, # 是否开启Debug模式
'TESTING': False, # 是否开启测试模式
'PROPAGATE_EXCEPTIONS': None,
'PRESERVE_CONTEXT_ON_EXCEPTION': None,
'SECRET_KEY': None,
'PERMANENT_SESSION_LIFETIME': timedelta(days=31), # session超时时间
'USE_X_SENDFILE': False,
'LOGGER_NAME': None,
'LOGGER_HANDLER_POLICY': 'always',
'SERVER_NAME': None,
'APPLICATION_ROOT': None,
'SESSION_COOKIE_NAME': 'session',
'SESSION_COOKIE_DOMAIN': None,
'SESSION_COOKIE_PATH': None,
'SESSION_COOKIE_HTTPONLY': True,
'SESSION_COOKIE_SECURE': False,
'SESSION_REFRESH_EACH_REQUEST': True,
'MAX_CONTENT_LENGTH': None,
'SEND_FILE_MAX_AGE_DEFAULT': timedelta(hours=12),
'TRAP_BAD_REQUEST_ERRORS': False,
'TRAP_HTTP_EXCEPTIONS': False,
'EXPLAIN_TEMPLATE_LOADING': False,
'PREFERRED_URL_SCHEME': 'http',
'JSON_AS_ASCII': True,
'JSON_SORT_KEYS': True,
'JSONIFY_PRETTYPRINT_REGULAR': True,
'JSONIFY_MIMETYPE': 'application/json',
'TEMPLATES_AUTO_RELOAD': None,
}
View Code
配置方式1:
app.config["DEBUG"] = True
# 由于Config对象本质上是字典,所以还可以使用
app.config.update({"DEBUG": "True"})
配置方式2:
新建一个 settings.py 文件,例如:
# settings.py
class Config(object):
DEBUG = False
TESTING = False
DATABASE_URI = 'sqlite://:memory:'
class ProductionConfig(Config):
DATABASE_URI = 'mysql://user@localhost/foo'
class DevelopmentConfig(Config):
DEBUG = True
class TestingConfig(Config):
TESTING = True
再使用:app.config.from_object("配置文件类的路径")
所以,生产环境就用生产环境的配置,开发时就用开发环境的配置。
三、路由系统
@app.route("/index", endpoint="xx") # endpoint相当于别名
def index():
print(url_for("xx")) # /index url_for("xx"),反向生成url,默认url_for("函数名")
return "index"
@app.route("/index/<user>") # 字符串
@app.route("/index/<int:id>")
@app.route("/index/<float:id>")
@app.route("/index/<path:path>")
@app.route("/login", methods=["GET", "POST"])
# 示例:
@app.route("/index/<user>")
def index(user):
return user
# 常用路由系统有以上五种,所有的路由系统都是基于以下对应关系来处理:
DEFAULT_CONVERTERS = {
'default': UnicodeConverter,
'string': UnicodeConverter,
'any': AnyConverter,
'path': PathConverter,
'int': IntegerConverter,
'float': FloatConverter,
'uuid': UUIDConverter,
}
反向生成带参数的URL,怎么做呢?
@app.route("/index/<int:id>")
def index(id):
print(url_for("index", id=id)) # id=1 生成固定参数的url
return "index"
CBV
from flask import Flask, views, url_for
app = Flask(__name__)
def auth(func):
@wraps(func)
def inner(*args, **kwargs):
print('before')
result = func(*args, **kwargs)
print('after')
return result
return inner
class IndexView(views.View):
methods = ['GET']
decorators = [auth, ]
def dispatch_request(self):
print('Index')
return 'Index'
app.add_url_rule('/index', view_func=IndexView.as_view(name='index')) # name=endpoint
# 或
class IndexView(views.MethodView):
methods = ['GET']
decorators = [auth, ]
def get(self):
return 'Index.GET'
def post(self):
return 'Index.POST'
app.add_url_rule('/index', view_func=IndexView.as_view(name='index')) # name=endpoint
View Code
@app.route和app.add_url_rule参数
rule # URL规则
view_func # 视图函数名称
defaults=None # 默认值,当URL中无参数,函数需要参数时,使用defaults={'k':'v'}为函数提供参数
endpoint=None # 名称,用于反向生成URL,即: url_for('名称')
methods=None # 允许的请求方式,如:["GET", "POST"]
strict_slashes=None # 对URL最后的 / 符号是否严格要求,
# 如:
@app.route('/index',strict_slashes=False),
访问 http://www.xx.com/index/ 或 http://www.xx.com/index 均可
@app.route('/index',strict_slashes=True)
仅访问 http://www.xx.com/index
redirect_to=None, # 重定向到指定地址
# 如:
@app.route('/index/<int:id>', redirect_to='/home/<id>')
或
def func(adapter, id):
return "/home/888"
@app.route('/index/<int:nid>', redirect_to=func)
subdomain=None, # 子域名访问
from flask import Flask, views, url_for
app = Flask(import_name=__name__)
app.config['SERVER_NAME'] = 'wupeiqi.com:5000'
@app.route("/", subdomain="admin")
def static_index():
"""Flask supports static subdomains
This is available at static.your-domain.tld"""
return "static.your-domain.tld"
@app.route("/dynamic", subdomain="<username>")
def username_index(username):
"""Dynamic subdomains are also supported
Try going to user1.your-domain.tld/dynamic"""
return username + ".your-domain.tld"
if __name__ == '__main__':
app.run()
View Code
自定制正则路由匹配
from flask import Flask, url_for
from werkzeug.routing import BaseConverter
app = Flask(import_name=__name__)
class RegexConverter(BaseConverter):
"""
自定义URL匹配正则表达式
"""
def __init__(self, map, regex):
super(RegexConverter, self).__init__(map)
self.regex = regex
def to_python(self, value):
"""
路由匹配时,匹配成功后传递给视图函数中参数的值
:param value:
:return:
"""
return int(value)
def to_url(self, value):
"""
使用url_for反向生成URL时,传递的参数经过该方法处理,返回的值用于生成URL中的参数
:param value:
:return:
"""
val = super(RegexConverter, self).to_url(value)
return val
# 添加到flask中
app.url_map.converters["regex"] = RegexConverter
@app.route("/index/<regex('d+'):id>")
def index(id):
return url_for("index", id=id)
if __name__ == "__main__":
app.run()
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四、请求和响应
from flask import Flask
from flask import request
from flask import render_template
from flask import redirect
from flask import make_response
from flask import jsonify
import os
app = Flask(__name__)
BASE_DIR = os.path.dirname(os.path.abspath(__file__))
@app.route("/login", methods=["GET", "POST"])
def login():
# 请求相关信息
request.method
request.args
request.form
request.values
request.cookies
request.headers
request.path
request.full_path
request.script_root
request.url
request.base_url
request.url_root
request.host_url
request.host
request.files
obj = request.files.get("the_file_name") # 拿到上传的文件名
obj.save(os.path.join(BASE_DIR, "files", obj.filename)) # 保存到本地路径
# 响应相关信息(响应体)
return "字符串"
data = {"key": "val"}
return jsonify(data) # 相当于 json.dumps(data)
return render_template("login.html", **{})
return redirect("/index")
# 设置响应头
response = make_response(render_template("index.html")) # 将响应内容封装到这个对象中,再设置
# response是flask.wrappers.Response类型
response.delete_cookie("key")
response.set_cookie("key", "val")
response.headers["key"] = "val"
return response
if __name__ == "__main__":
app.run()
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五、Session
session 对象,允许在不同请求间存储特定用户的信息。它是在 Cookies 的基础上实现的,并且对 Cookies 进行密钥签名要使用会话,需要设置一个密钥。
设置:session["user"] = "xx"
获取:session.get("user")
session["user"]
删除:session.pop("user", None)
# 可以在settings中设置秘钥
class DevelopmentConfig(Config):
DEBUG = True
SECRET_KEY = "asdf"
当请求刚到来:flask读取cookie中session对应的值,将该值解密并反序列化成字典,放入内存以便视图函数使用。
当请求结束时:flask会读取内存中字典的值,进行序列化、加密,写入到用户cookie中。
第三方session
"""
pip3 install redis
pip3 install flask-session
"""
import redis
from flask import Flask, session
from flask_session import Session
# from flask.ext.session import Session # 老版本,同 from flask_session import Session
app = Flask(__name__)
app.config["SESSION_TYPE"] = "redis"
app.config["SESSION_REDIS"] = redis.Redis(host="127.0.0.1",port=6379)
Session(app)
@app.route("/login")
def login():
session["user"] = "username"
return "login"
@app.route("/index")
def index():
print(session.get("user"))
return "index"
if __name__ == "__main__":
app.run()
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flash
临时存储数据,取了就没了;在session中存储一个数据,读取时通过pop将数据移除。
from flask import Flask, flash, get_flashed_messages
app = Flask(__name__)
@app.route('/test1')
def test1():
flash('aa', 'error') # 第二个参数:分类
flash('bb', 'error')
flash('cc', 'info')
return "Set Session"
@app.route('/test2')
def test2():
print(get_flashed_messages(category_filter=['error'])) # ['aaaaa', 'bbbbb']
return "Get Session"
if __name__ == "__main__":
app.run()
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六、模板
1、Flask 使用的是 Jinja2 模板,所以其语法和 Django 无差别。
{% for k,v in data.items() %}
<tr>
<td>{{ k }}</td>
<td>{{ v.name }}</td>
<td>{{ v["age"] }}</td>
<td>{{ v.get("hobby", "默认") }}</td>
</tr>
{% endfor %}
@app.route("/test")
def test():
txt1 = Markup("<h1>哈哈</h1>") # Markup相当于Django的mark_safe
txt2 = "<h1>呵呵</h1>"
return render_template("test.html", **{"txt1": txt1, "txt2": txt2})
#######################################################################
{{ txt1 }}
{{ txt2|safe }}
@app.template_global()
def func1(a1, a2):
return a1+a2
@app.template_filter()
def func2(a1, a2, a3):
return a1+a2+a3
# 调用方式,模板中:{{ func1(1,2) }} {{ 1|func2(2,3) }}
2、自定义模板方法
from flask import Flask, render_template
app = Flask(__name__)
def func():
return '<h1>哈哈哈</h1>'
@app.route('/test')
def test():
return render_template('test.html', xx=func)
if __name__ == "__main__":
app.run()
################################################
<!DOCTYPE html>
<html lang="zh-cn">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<h1>自定义函数</h1>
{{ xx()|safe }}
</body>
</html>
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macro
<!DOCTYPE html>
<html lang="zh-cn">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
{# 定义 #}
{% macro func(name, type='text', value='') %}
<input type="{{ type }}" name="{{ name }}" value="{{ value }}">
{% endmacro %}
{# 执行 #}
{{ func('password', type='password', value=123456) }}
</body>
</html>
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七、特殊装饰器
from flask import Flask
app = Flask(__name__)
@app.before_first_request
def before_first_request1():
print('before_first_request1')
@app.before_first_request
def before_first_request2():
print('before_first_request2')
@app.before_request
def before_request1():
print('before_request1')
@app.before_request
def before_request2():
print('before_request2')
@app.after_request
def after_request1(response):
print('after_request1', response)
return response
@app.after_request
def after_request2(response):
print('after_request2', response)
return response
@app.route('/')
def index():
return 'index'
if __name__ == '__main__':
app.run()
# before_first_request1
# before_first_request2
# before_request1
# before_request2
# after_request2 <Response 5 bytes [200 OK]>
# after_request1 <Response 5 bytes [200 OK]>
############################################
# 比较少的函数中需要额外添加功能,使用装饰器
def auth(func):
@functools.wraps(func)
def inner(*args, **kwargs):
if not session.get('user'):
return redirect(url_for('login'))
ret = func(*args, **kwargs)
return ret
return inner
@app.route('/index')
@auth
def index():
return 'index'
# 给全局加上登录验证
@app.before_request
def before_request():
if request.path == "/login":
return None
if session.get("user"):
return None
return redirect("login")
############################################
@app.errorhandler(404)
def page_not_found(error):
return '页面不见了'
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八、蓝图
蓝图用于为应用提供目录划分。
小中型:
account.py
from flask import Blueprint
from flask import render_template
account = Blueprint("account", __name__)
@account.route("/login", methods=["GET", "POST"])
def login():
return render_template("login.html")
course.py
from flask import Blueprint
course = Blueprint("course", __name__)
__init__.py
from flask import Flask
from .views.account import account
from .views.course import course
app = Flask(__name__, template_folder="templates", static_folder="statics", static_url_path="/static")
app.register_blueprint(account)
app.register_blueprint(course)
run.py
from pro_flask import app
if __name__ == "__main__":
app.run()
大型:
admin / __init__.py
from flask import Blueprint
admin = Blueprint(
"admin",
__name__,
template_folder="templates",
static_folder="static"
)
from . import views
admin / views.py
from . import admin
@admin.route("/index")
def index():
return "Admin.Index"
blog / __init__.py
from flask import Blueprint
blog = Blueprint(
"blog",
__name__,
template_folder="templates",
static_folder="static"
)
from . import view
blog / views.py
from . import blog
@blog.route("/index")
def index():
return "Blog.Index"
pro_flask / __init__.py
from flask import Flask
from .admin import admin
from .blog import blog
app = Flask(__name__)
app.debug = True
app.register_blueprint(admin, url_prefix="/api") # url前缀
app.register_blueprint(blog)
run.py
from pro_flask import app
if __name__ == "__main__":
app.run()
url_prefix参数的作用:
http://127.0.0.1:5000/index # Blog.Index
http://127.0.0.1:5000/api/index # Admin.Index
小中型应用程序目录:查看
大型应用程序目录:查看
九、Flask插件
http://flask.pocoo.org/extensions/