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I am trying to return return a list of dictionaries as part of a get request. I'm calling the function below. 

def get_data(id): selected_data = Database.get_date(id) json.dumps(selected_data, default=str) return jsonify({'data': selected_data})

selected_data is like

[{'date': datetime.date(2019, 1, 15), 'id': 1, 'name': 'John '}, {'date': datetime.date(2019, 1, 11), 'id': 2, 'name': 'Jane'}]

But, I am getting the error below

TypeError(repr(o) + " is not JSON serializable") TypeError: datetime.date(2019, 1, 15) is not JSON serializable

I've tried using json.dumps like this stack overflow thread suggests but still getting the same error.

Any help is appreciated.

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  • 1
    before jsonifty(), transform datetime.date to string or timestamp. Commented Mar 8, 2019 at 1:23
  • hey, ended up doing this. Thank you for responding. Commented Mar 8, 2019 at 2:14

4 Answers 4

Reset to default
3

You should realize a customer JSONEncoder

import json from datetime import date from datetime import datetime class JsonExtendEncoder(json.JSONEncoder): """ This class provide an extension to json serialization for datetime/date. """ def default(self, o): """ provide a interface for datetime/date """ if isinstance(o, datetime): return o.strftime('%Y-%m-%d %H:%M:%S') elif isinstance(o, date): return o.strftime('%Y-%m-%d') else: return json.JSONEncoder.default(self, o) if __name__ == '__main__': d = {'now': datetime.now(), 'today': date.today(), 'i': 100} ds = json.dumps(d, cls=JsonExtendEncoder) print "ds type:", type(ds), "ds:", ds l = json.loads(ds)
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1 Comment

It's a good idea to use isoformat instead of strftime, since it's a web standard that a lot of JavaScript libraries like.
1

Try one of the following

selected_data["date"] = selected_data["date"].isoformat() selected_data["date"] = selected_data["date"].strftime("%Y-%m-%d %H:%M:%S:%f") selected_data["date"] = str(selected_data["date"])
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this worked, selected_data["date"] = selected_data["date"].isoformat(). Accepting answer, thank you
1

Here's my approach to this. For flask and flask-restful users

import json # import json at the top # inside your def use this code jsonObj = json.dumps(my_dictionary, indent=1, sort_keys=True, default=str) return json.loads(jsonObj), 200
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0

if the string format is ok to return then convert the time and date field to string before sending

for i in range(len(selected_data)): selected_data[i]["date"] = str(selected_data[i]["date"])

then it will work fine

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