Save series of dictionaries to json file and retrieve it later - json

Question

So I am doing some work in python where I have to generate a series of dictionaries. I want to write each of these dictionaries to a single file.
The code to write the dictionaries look like this
with open('some_name.json', 'w') as fh:
data = function_generate_dict() # returns a dictionary
json.dump(data, fh)
That works fine and I can view the outputted file and can even load its content like thus
with open('some_name.json', 'r+') as rh:
for line in rh.readlines():
print(line)
But when I try to reload each dictionary from the file by doing this
with open('some_name', 'r') as rh:
cont = rh.read()
js =json.loads(cont)
I always get a JSONDecodeError: Extra data: line 1 column 220 (char 219)
which I suspect is coming from where one dictionary ends and another begins.
If I do this (json.load() instead of json.loads())
with open('some_name', 'r') as rh:
cont = rh.read()
js =json.load(cont)
I get this error AttributeError: 'str' object has no attribute 'read'
I have even tried using jsonl as the file format. But it doesn't work.
Here is a sample of the dictionaries I'm generating
{"measure_no": "0", "divisions": "256", "fifths": "5", "mode": "major", "beats": "4", "beat-type": "4", "transpose": "-9", "step": ["G"], "alter": ["1"], "octave": ["6"], "duration": ["256"], "syllabic": [], "text": []}{"measure_no": "1", "divisions": "256", "fifths": "5", "mode": "major", "beats": "4", "beat-type": "4", "transpose": "-9", "step": ["G", "G", "G", "G"], "alter": ["1", "1", "1", "1"], "octave": ["6", "6", "6", "6"], "duration": ["384", "128", "256", "256"], "syllabic": [], "text": []}{"measure_no": "2", "divisions": "256", "fifths": "5", "mode": "major", "beats": "4", "beat-type": "4", "transpose": "-9", "step": ["C", "G", "G"], "alter": ["1", "1", "1"], "octave": ["7", "6", "6"], "duration": ["384", "128", "512"], "syllabic": [], "text": []}

Answer 1

Your code dumps your dictionary to the end of the existing line:
This is 1: hard to read for human beings.
2: hard to read for the "readlines" function.
Add a new line after you dump your dictionnary.
with open('some_name.json', 'a') as fh:
''' note the use of 'a' instead of 'w', you want to append your
dictionnaries, not overwrite them every time '''
data = function_generate_dict() # returns a dictionary
json.dump(data, fh)
fh.write('\n')
Then when you want to read: from the file to a dictionary : you can do it with a loop which reads every line as a different json dictionary:
The way I would see it is make an empty dictionnary first to store every line.
jsonlist = []
'''make a list to store the json dictionaries'''
with open('some_name','r') as rh:
for line in rh.readlines():
jsonlist.append(json.loads(line))
You now have variable jsonlist for which each index is one of your json dictionaries, all that is left for you is to manipulate those indexes.
>>> jsonlist[0]
{'measure_no': '0', 'divisions': '256', 'fifths': '5', 'mode': 'major', 'beats': '4', 'beat-type': '4', 'transpose': '-9', 'step': ['G'], 'alter': ['1'], 'octave': ['6'], 'duration': ['256'], 'syllabic': [], 'text': []}