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Python 3: An interactive deep dive

Loading Data from a JSON File

Explore how to load and deserialize data from JSON files in Python. Understand the use of json.load to read JSON into Python objects and how to implement custom functions to convert JSON-compatible data back into original Python types like bytes and time structures.

We'll cover the following...

Like the pickle module, the json module has a load() function which takes a stream object, reads JSON-encoded data from it, and creates a new Python object that mirrors the JSON data structure.

Python 3.5
shell = 2
print (shell)
#2
del entry                                             #①
print (entry)
#Traceback (most recent call last):
#  File "<stdin>", line 1, in <module>
#NameError: name 'entry' is not defined
Python 3.5
import json
with open('entry.json', 'r', encoding='utf-8') as f:
     entry = json.load(f)                             #②
 
print (entry)                                         #③
#{'comments_link': None,
# 'internal_id': {'__class__': 'bytes', '__value__': [222, 213, 180, 248]},
# 'title': 'Dive into history, 2009 edition',
# 'tags': ['diveintopython', 'docbook', 'html'],
# 'article_link': 'http://diveintomark.org/archives/2009/03/27/dive-into-history-2009-edition',
# 'published_date': {'__class__': 'time.asctime', '__value__': 'Fri Mar 27 22:20:42 2009'},
# 'published': True}

① For demonstration purposes, switch to Python Shell #2 and delete the entry data structure that you created earlier in this chapter with the pickle module.

② In the simplest case, the json.load() function works the same as the pickle.load() function. You pass in a stream object and it returns a new Python object.

③ I have good news and bad news. Good news first: the json.load() function successfully read the entry.json file you created in Python Shell #1 and created a ...