"TypeError: (Integer) is not JSON serializable" when serializing JSON in Python?

Question

I am trying to send a simple dictionary to a json file from python, but I keep getting the "TypeError: 1425 is not JSON serializable" message.

import json
alerts = {'upper':[1425],'lower':[576],'level':[2],'datetime':['2012-08-08 15:30']}
afile = open('test.json','w')
afile.write(json.dumps(alerts,encoding='UTF-8'))
afile.close()

If I add the default argument, then it writes, but the integer values are written to the json file as strings, which is undesirable.

afile.write(json.dumps(alerts,encoding='UTF-8',default=str))

I found my problem. The issue was that my integers were actually type numpy.int64. — user1329894, Aug 13 '12 at 21:18
@user1329894 Post as a solution/explanation and self-close .. — , Aug 13 '12 at 21:19
-0 for writing a minimal repro that doesn't actually reproduce the bug. — Russell Borogove, Aug 13 '12 at 21:39
The underlying problem is the same: data that looks like an "ordinary" type, but is a different type that doesn't support serialization. In this case it was a Numpy numeric type instead of `int`; in the other case, a custom mapping instead of `dict`. — Karl Knechtel, Sep 08 '22 at 07:06

score 305 · Answer 1 · edited Apr 03 '18 at 14:29

305

I found my problem. The issue was that my integers were actually type numpy.int64.

edited Apr 03 '18 at 14:29

Andrea Bergonzo

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answered Aug 13 '12 at 21:36

user1329894

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23

I had to deal with this issue too, and your answer pointed me in the right direction. I just wanted to add [a link to another question](http://stackoverflow.com/questions/9452775/converting-numpy-dtypes-to-native-python-types) that can help in actually solving the problem. – JAC Nov 25 '13 at 17:35
20

That'd be nice if the JSON unserializable error message could display the type of the object... – Franck Dernoncourt Jul 21 '15 at 19:41
6

[Here](http://stackoverflow.com/a/27050186/310441) is a tidy solution that uses a custom serializer. – Owen Jun 17 '16 at 00:03
It works perfectly on ubuntu but not on windows. Please help. – Abhishek Lodha Jul 25 '17 at 10:08
Great catch. Happens with AWS Lambda (Python 3.6) serialization as well. (https://forums.aws.amazon.com/message.jspa?messageID=689708) – Jerdak Aug 24 '17 at 22:48
23

That's the problem, but what's the solution? – BallpointBen May 01 '18 at 16:12
6

x.astype(int) or int(x) – zelcon May 14 '18 at 09:58
1

x.astype(int) or int(x) not working in python3.5. this is what i am doing. data['id'] = data['id'].astype(int) – LMSharma Nov 23 '18 at 04:59
the serializer solution worked for me in my flask project – Raveen Beemsingh Dec 28 '18 at 13:41
For me, just int(x) is working, not astype(x). Strange. – Gaurav Bishnoi Sep 08 '19 at 04:40

hsc · Answer 2 · 2019-08-29T06:13:30.853

70

It seems like there may be a issue to dump numpy.int64 into json string in Python 3 and the python team already have a conversation about it. More details can be found here.

There is a workaround provided by Serhiy Storchaka. It works very well so I paste it here:

def convert(o):
    if isinstance(o, numpy.int64): return int(o)  
    raise TypeError

json.dumps({'value': numpy.int64(42)}, default=convert)

edited Aug 29 '19 at 06:13

answered May 29 '18 at 06:32

hsc

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A wonderful workaround provided by Serhiy. Please check his approach. And to add, just: json.dumps(yourObject, default=default); like here. – Pranzell Apr 16 '19 at 15:30

score 13 · Answer 3 · answered Jan 09 '20 at 05:52

as @JAC pointed out in the comments of the highest rated answer, the generic solution (for all numpy types) can be found in the thread Converting numpy dtypes to native python types.

Nevertheless, I´ll add my version of the solution below, as my in my case I needed a generic solution that combines these answers and with the answers of the other thread. This should work with almost all numpy types.

def convert(o):
    if isinstance(o, np.generic): return o.item()  
    raise TypeError

json.dumps({'value': numpy.int64(42)}, default=convert)

score 10 · Answer 4 · answered Jun 04 '19 at 17:11

10

Just convert numbers from `int64` (from numpy) to `int`.

For example, if variable x is a int64:

int(x)

If is array of int64:

map(int, x)

answered Jun 04 '19 at 17:11

Jonatas Eduardo

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score 8 · Answer 5 · edited Nov 02 '20 at 04:10

8

You have Numpy Data Type, Just change to normal int() or float() data type. it will work fine.

edited Nov 02 '20 at 04:10

shiva

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answered Aug 28 '18 at 15:50

Sriram Arvind Lakshmanakumar

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score 6 · Answer 6 · answered Feb 24 '20 at 13:18

This might be the late response, but recently i got the same error. After lot of surfing this solution helped me.

alerts = {'upper':[1425],'lower':[576],'level':[2],'datetime':['2012-08-08 15:30']}
def myconverter(obj):
        if isinstance(obj, np.integer):
            return int(obj)
        elif isinstance(obj, np.floating):
            return float(obj)
        elif isinstance(obj, np.ndarray):
            return obj.tolist()
        elif isinstance(obj, datetime.datetime):
            return obj.__str__()

Call myconverter in json.dumps() like below. json.dumps(alerts, default=myconverter).

score 4 · Answer 7 · answered Apr 07 '19 at 20:43

4

This solved the problem for me:

def serialize(self):
    return {
        my_int: int(self.my_int), 
        my_float: float(self.my_float)
    }

answered Apr 07 '19 at 20:43

Tobias Ernst

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score 4 · Answer 8 · edited Nov 02 '20 at 04:11

4

Same problem. List contained numbers of type numpy.int64 which throws a TypeError. Quick workaround for me was to

mylist = eval(str(mylist_of_integers))
json.dumps({'mylist': mylist})

which converts list to str() and eval() function evaluates the String like a Python expression and returns the result as a list of integers in my case.

edited Nov 02 '20 at 04:11

shiva

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answered Apr 24 '20 at 00:00

user319436

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Just noticed eval(str()) is very slow so use with caution. @shiva's answer is much better: json.dumps(alerts, default=myconverter) – user319436 Apr 24 '20 at 00:06

score 3 · Answer 9 · edited Nov 04 '20 at 05:15

3

Use the below code to resolve the issue.

import json
from numpyencoder import NumpyEncoder
alerts = {'upper':[1425],'lower':[576],'level':[2],'datetime':['2012-08-08 
15:30']}
afile = open('test.json','w')
afile.write(json.dumps(alerts,encoding='UTF-8',cls=NumpyEncoder))
afile.close()

edited Nov 04 '20 at 05:15

shiva

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answered Jun 01 '20 at 05:25

krishna kumar mishra

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score 1 · Answer 10 · edited Oct 30 '18 at 13:34

1

Alternatively you can convert your object into a dataframe first:

df = pd.DataFrame(obj)

and then save this dataframe in a json file:

df.to_json(path_or_buf='df.json')

Hope this helps

edited Oct 30 '18 at 13:34

toti08

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answered Oct 30 '18 at 12:46

kartik

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"TypeError: (Integer) is not JSON serializable" when serializing JSON in Python?

10 Answers10

Just convert numbers from `int64` (from numpy) to `int`.

Linked

"TypeError: (Integer) is not JSON serializable" when serializing JSON in Python?

10 Answers10

Just convert numbers from int64 (from numpy) to int.

Linked

Just convert numbers from `int64` (from numpy) to `int`.