Python json.load 返回字符串而不是字典

Question

I'm taking in a json file and only copying the necesary keys and their values to a new json file. I'm getting the error "TypeError: string indices must be integers" in reference to where I'm copying the values to myDict. From what I gather, json.load is returning a string rather than a dictionary. I validated the json file and it has valid json format. I'm using Python 2.7.12. I've searched everywhere and haven't found an answer that answers my specific problem. Any help you can give me is greatly appreciated.

import os
import sys
import json

def stripSpec(inp, outp):
    #Load json file as python dictionary
    obj  = json.load(open(inp, "r"))

    result=[]

    #Go through JSON and save necessary keys and values
    for i in obj:
        myDict = {}
        myDict["id"]=i.get('id').get('value')
        myDict["data"]["BaselineExposure"]=i.get('data').get('BaselineExposure').get('value')
        myDict["data"]["ColorMatrix2"]=i.get('data').get('ColorMatrix2').get('value')
        result.append(myDict)

    # Output the updated file with pretty JSON
    open(outp, "w").write(json.dumps(result, sort_keys=True, indent=4, ensure_ascii=False, separators=(',', ':')))
    return

#Save input and output paths as variables
inp = sys.argv[1]
outp = sys.argv[2]

#Call function
stripSpec(inp, outp)

an example of the json is here. It has been drastically reduced but basically there is more entries for each camera model

[
{ "id": "Canon EOS 100D",
 "data":[{
  "SourceFile": "./Canon 100D/canon_eos_100d_11.dng",
  "ExifToolVersion": 10.07,
  "Directory": "./Canon 100D",
  "FileSize": "18 MB",
  "FileModifyDate": "2016:05:02 23:03:14-07:00",
  "FileAccessDate": "2016:05:03 01:45:03-07:00",
  "FileInodeChangeDate": "2016:05:02 23:03:14-07:00",
  "FilePermissions": "rw-r--r--",
  "ColorMatrix2": "0.6602 -0.0841 -0.0939 -0.4472 1.2458 0.2247 -0.0975 0.2039 0.6148",
  "CameraCalibration1": "1.0648 0 0 0 1 0 0 0 0.9881",
  "CameraCalibration2": "1.0648 0 0 0 1 0 0 0 0.9881",
  "AnalogBalance": "1 1 1",
  "AsShotNeutral": "0.512769 1 0.584809",
  "BaselineExposure": -0.25,
  "RedBalance": 1.950195
  }]
},

Answer 1

In your json stub "data" key contains list. In your code you refer to it as a dictionary: i.get('data').get('BaselineExposure')

Instead you should iterate through your "data" . For example:

data = i.get('data')
for d in data:
    print(d.get('BaselineExposure'))

So basically be careful with nested items.

Also why do you use i.get('id').get('value') . Instead i.get('id') should be enough and additional .get('value') should raise AttributeError , isn't it?

Answer 2

Overview: I assume the json is stored as a dictionary. I convert the dictionary to a json string using json.dumps. I pip install json2xml json2xml to convert the json string so it can be converted to xml. I then load the xml into a dom tree for searching. I search for the node in the xml tree using getElementsByTagName and display the value. My approach is more programmer friendly.

from json2xml import json2xml
from json2xml.utils import readfromurl, readfromstring, readfromjson
from xml.dom.minidom import parse, parseString

dict={
  "id": "Canon EOS 100D",
  "data": [{
    "SourceFile": "./Canon 100D/canon_eos_100d_11.dng",
    "ExifToolVersion": 10.07,
    "Directory": "./Canon 100D",
    "FileSize": "18 MB",
    "FileModifyDate": "2016:05:02 23:03:14-07:00",
    "FileAccessDate": "2016:05:03 01:45:03-07:00",
    "FileInodeChangeDate": "2016:05:02 23:03:14-07:00",
    "FilePermissions": "rw-r--r--",
    "ColorMatrix2": "0.6602 -0.0841 -0.0939 -0.4472 1.2458 0.2247 -0.0975 0.2039 0.6148",
    "CameraCalibration1": "1.0648 0 0 0 1 0 0 0 0.9881",
    "CameraCalibration2": "1.0648 0 0 0 1 0 0 0 0.9881",
    "AnalogBalance": "1 1 1",
    "AsShotNeutral": "0.512769 1 0.584809",
    "BaselineExposure": -0.25,
    "RedBalance": 1.950195
    }]
 }

 #convert dictionary to a string
 json_data=json.dumps(dict,indent=4)
 data=readfromstring(json_data)
 xml=json2xml.Json2xml(data).to_xml()

 dom=parseString(xml)

 element=dom.getElementsByTagName('BaselineExposure') 
 print(element[0].firstChild.nodeValue)