TypeError：字符串索引必须是整数，而不是str //尝试获取key的值

Question

I'm trying to get a key from a value that I am returned with, but when i use the easy approach to just get the value of a specific key I get the error: TypeError: string indices must be integers, not str

I also tried .get() method, but it did not work either. Could someone please point me out what I am doing wrong?

>>> import urllib2
>>> url = 'http://192.168.250.1/ajax.app?SessionId=8ef05397-ef00-451a-bc1c-c0d61
5a4811d&service=getDp&plantItemId=1413'
>>> response = urllib2.urlopen(url)
>>> dict = response.read()
>>> dict
'{"service":"getDp","plantItemId":"1413","value":" 21.4","unit":"\xc2\xb0C"}'
>>> dict['value']
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: string indices must be integers, not str

Answer 1

Looks like 'dict' is a variable of type string, not a dictionary. You should parse the string into a suitable dictionary format (like JSON). Here's a code that will resolve that issue:

import json
json_string = response.read()
dict = json.loads(json_string)

Now, for dict['value'] you will get what you need.

Answer 2

response.read() is returning an object of type string and not a dictionary and you can index a string using only integer indices and hence you are getting your error.

You need to parse this string and convert it to a dictionary. To convert a string of a dictionary back to a dictionary you can do this:

import ast
dict = ast.literal_eval(dict)
print dict['value']

Tried it on my machine with Python 2.7 and it works.