flask快速上手

轻量级框架 后端框架

• flask路由用来匹配url
• request对象
• 模板
• flask数据库
• 表单
• 
  

​​pip install flask -i https://pypi.douban.com ​​

from flask import Flask
# 实例化 
app = Flask(__name__)
# 装饰器
@app.route("/")
def hello_world():
    return "<p>Hello, World!</p>"
app.run()

__name__指的是当前文件
两种路由请求,get请求和post请求

@app.route("/hi",methods=['GET','POST'])
def hello_world():
    return "<p>Hello, World!</p>"

flask路由-变量规则
127.0.0.1:5000/user/1

@app.route("/user/<id>")
def index(id):
    if id == 1:
        return 'python'
    return "<p>Hello, World!</p>"

string接受任何不包含斜杠的文本
int接受正整数
float接受正浮点数
path接受包含斜杠的文本

@app.route("/user/<int:id>")
def index(id):
    if id == 1:
        return 'python'
    return "<p>Hello, World!</p>"

自定义转换器
{‘re’,RegexConverter}

from werkzeug.routing import BaseConverter
from flask import Flask
app = Flask(__name__)
class RegexConverter(BaseConverter):
    def __init__(self,url_map,regex):
        #调用父类方法
        super(RegexConverter, self).__init__(url_map)
        self.regex = regex
    def to_python(self, value):
        #父类的方法功能已经实现好了
        print('to_python方法被调用')
        return value
# 将自定义的转换器类添加到flask应用中
app.url_map.converters['re'] = RegexConverter
@app.route('/index/<re("123"):value>')
def index(value):
    print(value)
    return 'hello'
if __name__ == '__main__':
    app.run()

重定向到自己路由（函数）中

from flask import  Flask,redirect,url_for
app = Flask(__name__)
@app.route('/index')
def index():
    return redirect(url_for('hello'))
@app.route('/')
def hello():
    return 'nb'
if __name__ == '__main__':
    app.run()

返回json数据给前端

from flask import  Flask,make_response,json,jsonify
app = Flask(__name__)
app.config['JSON_AS_ASCII'] = False
@app.route('/index')
def index():
    data = {
        'name': 'zhangsan'
    }
    # response = make_response(json.dumps(data,ensure_ascii=False))
    # response.mimetype = 'application/json'
    # return response
    return jsonify(data,)
if __name__ == '__main__':
    app.run()

abort函数

from flask import Flask,abort,request,render_template
app = Flask(__name__)
@app.route('/index',methods=['GET','POST'])
def index():
    if request.method == 'GET':
        return render_template('index.html')
    if request.method =='POST':
        name = request.form.get('name')
        password = request.form.get('password')
        if name == 'zhangsan' and password == '123':
            return 'login success'
        else:
            abort(404)
            return None
    return '123'
if __name__ == '__main__':
    app.run()

自定义异常

from flask import Flask,abort,request,render_template
app = Flask(__name__)
@app.route('/index',methods=['GET','POST'])
def index():
    if request.method == 'GET':
        return render_template('index.html')
    if request.method =='POST':
        name = request.form.get('name')
        password = request.form.get('password')
        if name == 'zhangsan' and password == '123':
            return 'login success'
        else:
            abort(404)
            return None
#自定义错误处理方法
@app.errorhandler(404)
def handle_404_error(err):
    return '出现了404错误 错误信息是%s'%err
if __name__ == '__main__':
    app.run()

自定义过滤器

定义表单模型类