CODEWITHSUNDEEP
pythonjsondictionary
gosok
gosok

Reputation: 23

Dumping a list of dictionary to JSON gives ValueError: Extra Data

I am doing an assignment on python and I was trying to dump a dictionary that contains a list of another dictionary into JSON. However, upon running the data, it made an error:

File "D:\Users\XXXXX\Anaconda2\lib\json\decoder.py", line 367, in decode raise ValueError(errmsg("Extra data", s, end, len(s))) ValueError: Extra data: line 1 column 76 - line 1 column 1434 (char 75 - 1433)

Here is the code snippet on the JSON writer:

def savelist(self):
    data={}
    f = open('partjson.txt','w')
    for i in range(self.datacount):
        data.setdefault("data",[]).append({'name':self.namelist[i], 'numid':str(self.numidlist[i]), 'height':str(self.heightlist[i]), 'length':str(self.lengthlist[i])})
        json.dump(data,f)
    f.close()

The data file outputted is not as intended since the dictionary "data" is outputted multiple time instead of only once at the beginning.

{"data": [{"length": "3", "numid": "1", "name": "first", "height": "2.0"}]}{"data": [{"length": "3", "numid": "1", "name": "first", "height": "2.0"}, {"length": "4", "numid": "2", "name": "second", "height": "3.0"}]}

Could you please tell me what is wrong with my method? Thank you

Upvotes: 0

Views: 619

Answers (1)

Krei
Krei

Reputation: 26

You misplaced the indentation for the json.dump(data, f). The data.setdefault is called on every loop, creating your so-called "data" dictionary entry. This creates the error. The code should be:

def savelist(self):
data={}
f = open('partjson.txt','w')
for i in range(self.datacount):
    data.setdefault("data",[]).append({'name':self.namelist[i], 'numid':str(self.numidlist[i]), 'height':str(self.heightlist[i]), 'length':str(self.lengthlist[i])})
json.dump(data,f)
f.close()

Upvotes: 1

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