python中eval()和json.dumps的使用

在python中通过requests.get(url)获取json数据，此时可能需要eval进行解析。

# -*- coding: utf-8 -*-
import requests

r = requests.get(url='your url address')  # 最基本的GET请求
# print r.content
# print '......................'
# print len(r.json()
# print '......................'
# print len(r.json()['data'])
# print '......................'
print r.json()['data'][6]['type']          # area
print '......................'
print r.json()['data'][6]['radarcoor']
print '......................'
print r.json()['data'][6]['radarcoor'][0]      # 错误
print '......................'
print eval("r.json()['data'][6]['radarcoor']")[0]           # 错误
print '......................'
print eval("("+r.json()['data'][6]['radarcoor']+")")[0]       # 正确的写法

此时r.json()返回：

r.json()['data'][6]['radarcoor']返回：

要获取其中每一项，则需要使用eval()函数进行解析：

2.json.dumps()

功能：将python中的数据类型转换成str类型

# json.dumps()
mylist = [123, {'name': 'dragon'}, {'location': ('ch', 'nt')}]
encoded_json = json.dumps(mylist)
print isinstance(encoded_json, str)  # True
print encoded_json       # [123, {"name": "dragon"}, {"location": ["ch", "nt"]}]

# json.loads()
# decoded_json = json.loads(encoded_json)
# print isinstance(decoded_json, list)      # True
# print decoded_json     # [123, {u'name': u'dragon'}, {u'location': [u'ch', u'nt']}]

# eval()
decoded_json = eval(encoded_json)
print isinstance(decoded_json, list)  # True
print decoded_json       # [123, {'name': 'dragon'}, {'location': ['ch', 'nt']}]