What is the difference between json.load() and json.loads() functions

In Python, what is the difference between json.load() and json.loads()?

I guess that the load() function must be used with a file object (I need thus to use a context manager) while the loads() function take the path to the file as a string. It is a bit confusing.

Does the letter "s" in json.loads() stand for string?

Thanks a lot for your answers!

Yes, s stands for string. The json.loads function does not take the file path, but the file contents as a string. Look at the documentation.

Just going to add a simple example to what everyone has explained,

json.load()

json.load can deserialize a file itself i.e. it accepts a file object, for example,

# open a json file for reading and print content using json.load
with open("/xyz/json_data.json", "r") as content:
  print(json.load(content))

will output,

{u'event': {u'id': u'5206c7e2-da67-42da-9341-6ea403c632c7', u'name': u'Sufiyan Ghori'}}

If I use json.loads to open a file instead,

# you cannot use json.loads on file object
with open("json_data.json", "r") as content:
  print(json.loads(content))

I would get this error:

TypeError: expected string or buffer

json.loads()

json.loads() deserialize string.

So in order to use json.loads I will have to pass the content of the file using read() function, for example,

using content.read() with json.loads() return content of the file,

with open("json_data.json", "r") as content:
  print(json.loads(content.read()))

Output,

{u'event': {u'id': u'5206c7e2-da67-42da-9341-6ea403c632c7', u'name': u'Sufiyan Ghori'}}

That's because type of content.read() is string, i.e. <type 'str'>

If I use json.load() with content.read(), I will get error,

with open("json_data.json", "r") as content:
  print(json.load(content.read()))

Gives,

AttributeError: 'str' object has no attribute 'read'

So, now you know json.load deserialze file and json.loads deserialize a string.

Another example,

sys.stdin return file object, so if i do print(json.load(sys.stdin)), I will get actual json data,

cat json_data.json | ./test.py

{u'event': {u'id': u'5206c7e2-da67-42da-9341-6ea403c632c7', u'name': u'Sufiyan Ghori'}}

If I want to use json.loads(), I would do print(json.loads(sys.stdin.read())) instead.

Documentation is quite clear: https://docs.python.org/2/library/json.html

json.load(fp[, encoding[, cls[, object_hook[, parse_float[, parse_int[, parse_constant[, object_pairs_hook[, **kw]]]]]]]])

Deserialize fp (a .read()-supporting file-like object containing a JSON document) to a Python object using this conversion table.

json.loads(s[, encoding[, cls[, object_hook[, parse_float[, parse_int[, parse_constant[, object_pairs_hook[, **kw]]]]]]]])

Deserialize s (a str or unicode instance containing a JSON document) to a Python object using this conversion table.

So load is for a file, loads for a string

QUICK ANSWER (very simplified!)

json.load() takes a FILE

json.load() expects a file (file object) - e.g. a file you opened before given by filepath like 'files/example.json'.

json.loads() takes a STRING

json.loads() expects a (valid) JSON string - i.e. {"foo": "bar"}

EXAMPLES

Assuming you have a file example.json with this content: { "key_1": 1, "key_2": "foo", "Key_3": null }

>>> import json
>>> file = open("example.json")

>>> type(file)
<class '_io.TextIOWrapper'>

>>> file
<_io.TextIOWrapper name='example.json' mode='r' encoding='UTF-8'>

>>> json.load(file)
{'key_1': 1, 'key_2': 'foo', 'Key_3': None}

>>> json.loads(file)
Traceback (most recent call last):
  File "/usr/local/python/Versions/3.7/lib/python3.7/json/__init__.py", line 341, in loads
TypeError: the JSON object must be str, bytes or bytearray, not TextIOWrapper


>>> string = '{"foo": "bar"}'

>>> type(string)
<class 'str'>

>>> string
'{"foo": "bar"}'

>>> json.loads(string)
{'foo': 'bar'}

>>> json.load(string)
Traceback (most recent call last):
  File "/usr/local/python/Versions/3.7/lib/python3.7/json/__init__.py", line 293, in load
    return loads(fp.read(),
AttributeError: 'str' object has no attribute 'read'