python string.Template 实现$var,${var} ,#var替换，比如接口实现参数化

from string import  Template
import json

class ReplaceTepmlate(Template):
    delimiter ="${}"


def test_example1():
    a={"a":[{"c":1,'b':'${env}'},{"c":"${ip}"}]}
    string_text=json.dumps(a)
    # will replace like this {"a": [{"c": 1, "b": "litao"}, {"c": "10"}]}
    print(Template(string_text).substitute({"env":"litao","ip":10}))

class TemplateUserDefine(Template):
    delimiter = '$'


def test_example2():
    """ test $$env replace escape,$$不替换"""

    b={"test":11,'array':{"data":["hello",'$name'],"error":{"email":'$$env'}}}
    s=json.dumps(b)
    # will not replace $$env it keep self $env
    #{"test": 11, "array": {"data": ["hello", "zhangsan"], "error": {"email": "$env"}}}
    print(TemplateUserDefine(s).substitute({"name":'zhangsan',"env":111}))

class TemplateSpecial(Template):
    delimiter = '#'

def test_example3():
    # test # define variable replace
    test='hello,#var,i test args replace instead of kwargs .'
    ret=TemplateSpecial(test).substitute(var=111)
    # hello,111,i test args replace instead of kwargs .
    print(ret)
if __name__ == '__main__':
    test_example2()


# 优雅的合并dict

foo=dict(a=1,b=2)
bar=dict(key="value")
# you will get {'a': 1, 'b': 2, 'key': 'value'}
print({**foo,**bar})

应用篇：django 替换请求头或者body 参数：

import os
import django
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'mall.settings')
django.setup()
from platformapp.models import UserVariable,JsonModels
import json
from jsonpath import jsonpath
import re
import operator

def demo():
    user_var_object= UserVariable.objects.filter(id=7).first()
    var=user_var_object.variables
    json_model=JsonModels.objects.filter(id=7).first()
    content=substitute_content(json_model.attrs,var) # dict
    res=JsonModels.objects.filter(id=7).update(attrs=content)
    print(res)

def substitute_content(content:dict,replace_kwargs:dict)->dict:
    """
    @:param content of replace contains ${var_name}
    @:param replace_kwargs is the replace kwargs
    @:exception: use json string to serialize  int,float,list
    """
    # todo replace header'value  or request body data ${variable}
    dump_string = json.dumps(content)
    for k,v in replace_kwargs.items():
        if isinstance(v,(int,float,list)):
            res = dump_string.replace('"${' + str(k) + '}"', json.dumps(v))
            dump_string = res
        else:
            res=dump_string.replace('${' + str(k) + '}', str(v))
            dump_string=res
    contents=json.loads(dump_string)
    return contents

def test_suite_replace():
    res= substitute_content({"test": "${user}", "hex": "${pwd}","testlist":"${args}","at":{"a":{"k":"${user}"}}},
                         {"user": "hello", "pwd": 2.22,"args":[1,"22"]})
    print(res)

def json_recur(data,key_rex=None,v_rex=None):
    if isinstance(data,dict):
        for key,value in data.items():
            # print("key:",key,"value:",value,'===')
            if isinstance(value,dict):
                json_recur(value)
            elif isinstance(value,list):
                print(value,type(value),"@@@@@@@@")
                for i in  value:
                    json_recur(i)
            else:
                print(value,"--------???? ????? ",type(value))
    elif isinstance(data,list):
        for i in data:
            json_recur(i)
    else:
        print(data,type(data),"!!!!!!!!")

def jsonpath_extractor(json_expr:str,body,index=0):
        """
        @:param: json path expression $..data
        @:param body the substitute body support [dict,str]
        @index substitute value index default is 0 ,if -1 return all value
        """
        if isinstance(body,str):
            body=json.loads(body)
        elif isinstance(body,dict):
           pass
        else:
            raise ValueError("body type must be dict or string")
        extract_value= jsonpath(body, json_expr)
        if extract_value:
            if index==-1:
                return extract_value
            else:
                return extract_value[index] or None
        else: return None

def  regx_extractor(regx_expr,string:str,count=0):
    """
    :param regx_expr:
    :param string:
    :param count:
    :return: string
    r=re.findall(regx_expr,string)
    """
    results=re.findall(regx_expr,string)
    if results:
        return  results[count]
    return None

def assert_result(expect,actual,flag='eq'):
    """
    :param expect:
    :param actual:
    :param flag: default is eq
    :return:if  True else False
    """
    if flag == 'eq': # a==b
        return operator.eq(expect,actual)
    if flag == "ne": # a!=b
        return operator.ne(expect,actual)
    if flag == "lt": # a<b
        return operator.lt(expect,actual)
    if  flag == "le": # a<=b | b contains a
        return operator.le(expect,actual)
    if flag == "gt":  # a>b
        return operator.gt(expect,actual)
    if flag == "ge":  # a>=b | a contains b
        return operator.ge(expect,actual)

if __name__ == '__main__':
    test_suite_replace()