How to load a list from a json file? - json

Question

I have this data inside my text.txt:
[{"title": "T", "genre": "G", "director": "D", "year": "R"}]
When I try to load it this way (line 6):
class Movie:
def __init__(self, **new_movie):
movies = []
with open ('movies.txt', 'r') as f:
if f.read() != '':
movies = json.load(f)
if not verify_uniqueness(new_movie, movies):
print('Movie has already been added.')
else:
self.title = new_movie['title']
self.genre = new_movie['genre']
self.director = new_movie['director']
self.year = new_movie['year']
I get the following error:
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/json/__init__.py", line 299, in load
parse_constant=parse_constant, object_pairs_hook=object_pairs_hook, **kw)
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/json/__init__.py", line 354, in loads
return _default_decoder.decode(s)
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/json/decoder.py", line 339, in decode
obj, end = self.raw_decode(s, idx=_w(s, 0).end())
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/json/decoder.py", line 357, in raw_decode
raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)
How can I read the data?

Answer 1

with open ('movies.txt', 'r') as f:
if f.read() != '':
movies = json.load(f)
Since f is essentially a generator, calling f.read() in the if condition consumes it, and by the time json.load(f) is called f is empty:
with open ('movies.txt') as f:
print(f.read())
# file content
print(f.read())
# ''
You have to store the file's content in a variable and then use json.loads:
with open('movies.txt') as f:
content = f.read()
if content:
movies = json.loads(content)