How to overcome datetime datetime not JSON serializable

Question

I have a basic dict as follows   sample      sample  title      String  sample  somedate     somedatetimehere   When I try to do jsonify sample  I get   TypeError  datetime datetime 2012  8  8  21  46  24  862000  is not JSON serializable   What can I do such that my dictionary sample can overcome the error above   Note  Though it may not be relevant  the dictionaries are generated from the retrieval of records out of mongodb where when I print out str sample  somedate     the output is 2012-08-08 21 46 24 862000

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Convert the date  to  string  date   str datetime datetime somedatetimehere

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if you are using python3 7  then the best solution is using datetime isoformat   and datetime fromisoformat    they work with both naive and aware datetime objects      usr bin env python3 7  from datetime import datetime from datetime import timezone from datetime import timedelta import json  def default obj       if isinstance obj  datetime           return     isoformat   obj isoformat         return super   default obj   def object hook obj        isoformat   obj get   isoformat       if  isoformat is not None          return datetime fromisoformat  isoformat      return obj  if   name         main          d      now   datetime 2000  1  1        d      now   datetime 2000  1  1  tzinfo timezone timedelta hours -8          s   json dumps d  default default      print s      print d    json loads s  object hook object hook     output     now      isoformat    2000-01-01T00 00 00-08 00    True   if you are using python3 6 or below  and you only care about the time value  not the timezone   then you can use datetime timestamp   and datetime fromtimestamp   instead   if you are using python3 6 or below  and you do care about the timezone  then you can get it via datetime tzinfo  but you have to serialize this field by yourself  the easiest way to do this is to add another field  tzinfo in the serialized object   finally  beware of precisions in all these examples

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Here is a simple solution to over come  datetime not JSON serializable  problem    enco   lambda obj        obj isoformat       if isinstance obj  datetime datetime      or isinstance obj  datetime date      else None    json dumps   date   datetime datetime now     default enco    Output -    date    2015-12-16T04 48 20 024609

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I have an application with a similar issue  my approach was to JSONize the datetime value as a 6-item list  year  month  day  hour  minutes  seconds   you could go to microseconds as a 7-item list  but I had no need to   class DateTimeEncoder json JSONEncoder       def default self  obj           if isinstance obj  datetime datetime               encoded object   list obj timetuple    0 6          else              encoded object  json JSONEncoder default self  obj          return encoded object  sample      sample  title      String  sample  somedate     datetime datetime now    print sample print json dumps sample  cls DateTimeEncoder    produces     somedate   datetime datetime 2013  8  1  16  22  45  890000    title    String     somedate    2013  8  1  16  22  45    title    String

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I had encountered same problem when externalizing django model object to dump as JSON  Here is how you can solve it   def externalize model obj     keys   model obj  meta get all field names      data        for key in keys      if key     date time         date time obj   getattr model obj  key        data key    date time obj strftime   A  d   B  Y       else        data key    getattr model obj  key    return data

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def j serial o         self contained     from datetime import datetime  date     return str o  split      0  if isinstance o   datetime  date   else None   Usage of above utility   import datetime serial d   j serial datetime datetime now    if serial d      print serial d     output  2018-02-28 02 23 15

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For others who do not need or want to use the pymongo library for this   you can achieve datetime JSON conversion easily with this small snippet   def default obj          Default JSON serializer         import calendar  datetime      if isinstance obj  datetime datetime           if obj utcoffset   is not None              obj   obj - obj utcoffset           millis   int              calendar timegm obj timetuple      1000               obj microsecond   1000                   return millis     raise TypeError  Not sure how to serialize  s     obj      Then use it like so   import datetime  json print json dumps datetime datetime now    default default    output  nbsp    1365091796124

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Generally there are several ways to serialize datetimes  like    ISO string  short and can include timezone info  e g   jgbarah s answer Timestamp  timezone data is lost   e g   JayTaylor s answer Dictionary of  properties  including timezone     If you re okay with the last way  the json tricks package handles dates  times and datetimes including timezones   from datetime import datetime from json tricks import dumps foo     title    String    datetime   datetime 2012  8  8  21  46  24  862000   dumps foo    which gives     title    String    datetime       datetime     null   year   2012   month   8   day   8   hour   21   minute   46   second   24   microsecond   862000     So all you need to do is   pip install json tricks    and then import from json tricks instead of json   The advantage of not storing it as a single string  int or float comes when decoding  if you encounter just a string or especially int or float  you need to know something about the data to know if it s a datetime  As a dict  you can store metadata so it can be decoded automatically  which is what json tricks does for you  It s also easily editable for humans   Disclaimer  it s made by me  Because I had the same problem

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Convert the date to a string  sample  somedate     str  datetime utcnow

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I may not 100  correct but  this is the simple way to do serialize     usr bin python import datetime json  sampledict      sampledict  a      some string  sampledict  b     datetime datetime now    print sampledict     output     a    some string    b   datetime datetime 2017  4  15  5  15  34  652996     print json dumps sampledict       output     Traceback  most recent call last     File    jsonencodedecode py   line 10  in  lt module gt      print json dumps sampledict    File   usr lib python2 7 json   init   py   line 244  in dumps     return  default encoder encode obj    File   usr lib python2 7 json encoder py   line 207  in encode     chunks   self iterencode o   one shot True    File   usr lib python2 7 json encoder py   line 270  in iterencode     return  iterencode o  0    File   usr lib python2 7 json encoder py   line 184  in default     raise TypeError repr o      is not JSON serializable   TypeError  datetime datetime 2017  4  15  5  16  17  435706  is not JSON serializable        sampledict  b     datetime datetime now   strftime   B  d   Y  H  M  p    afterdump   json dumps sampledict   print afterdump   output     a    some string    b    April 15  2017 05 18 AM    print type afterdump    lt type  str  gt    afterloads   json loads afterdump    print afterloads   output    u a   u some string   u b   u April 15  2017 05 18 AM     print type afterloads    output   lt type  dict  gt

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Here is my full solution for converting datetime to JSON and back    import calendar  datetime  json  def outputJSON obj          Default JSON serializer          if isinstance obj  datetime datetime           if obj utcoffset   is not None              obj   obj - obj utcoffset            return obj strftime   Y- m- d  H  M  S  f       return str obj   def inputJSON obj       newDic           for key in obj          try              if float key     int float key                    newKey   int key              else                  newKey   float key               newDic newKey    obj key              continue         except ValueError              pass          try              newDic str key     datetime datetime strptime obj key     Y- m- d  H  M  S  f               continue         except TypeError              pass          newDic str key     obj key       return newDic  x     Date   datetime datetime utcnow    34  89 9  12 3  90  45  67   Extra   6   print x  with open  my dict json    w   as fp      json dump x  fp  default outputJSON   with open  my dict json   as f      my dict   json load f  object hook inputJSON   print my dict   Output    Date   datetime datetime 2013  11  8  2  30  56  479727   34  89 9  45  67  12 3  90   Extra   6    Date   datetime datetime 2013  11  8  2  30  56  479727   34  89 9  45  67  12 3  90   Extra   6    JSON File    Date    2013-11-08 02 30 56 479727    34   89 9   45   67   12 3   90   Extra   6    This has enabled me to import and export strings  ints  floats and datetime objects  It shouldn t be to hard to extend for other types

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Building on other answers  a simple solution based on a specific serializer that just converts datetime datetime and datetime date objects to strings   from datetime import date  datetime  def json serial obj          JSON serializer for objects not serializable by default json code         if isinstance obj   datetime  date            return obj isoformat       raise TypeError   Type  s not serializable    type obj     As seen  the code just checks to find out if object is of class datetime datetime or datetime date  and then uses  isoformat   to produce a serialized version of it  according to ISO 8601 format  YYYY-MM-DDTHH MM SS  which is easily decoded by JavaScript   If more complex serialized representations are sought  other code could be used instead of str    see other answers to this question for examples   The code ends by raising an exception  to deal with the case it is called with a non-serializable type   This json serial function can be used as follows   from datetime import datetime from json import dumps  print dumps datetime now    default json serial    The details about how the default parameter to json dumps works can be found in Section Basic Usage of the json module documentation

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You have to supply a custom encoder class with the cls parameter of json dumps  To quote from the docs    gt  gt  gt  import json  gt  gt  gt  class ComplexEncoder json JSONEncoder           def default self  obj               if isinstance obj  complex                   return  obj real  obj imag              return json JSONEncoder default self  obj       gt  gt  gt  dumps 2   1j  cls ComplexEncoder    2 0  1 0    gt  gt  gt  ComplexEncoder   encode 2   1j    2 0  1 0    gt  gt  gt  list ComplexEncoder   iterencode 2   1j          2 0          1 0          This uses complex numbers as the example  but you can just as easily create a class to encode dates  except I think JSON is a little fuzzy about dates

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A quick fix if you want your own formatting  for key val in sample items        if isinstance val  datetime           sample key        Y- m- d  H  M  S   format val   you can add different formating here json dumps sample

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The json dumps method can accept an optional parameter called default which is expected to be a function  Every time JSON tries to convert a value it does not know how to convert it will call the function we passed to it  The function will receive the object in question  and it is expected to return the JSON representation of the object   def myconverter o    if isinstance o  datetime datetime       return o   str      print json dumps d  default   myconverter

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If you are using the result in a view be sure to return a proper response  According to the API  jsonify does the following      Creates a Response with the JSON representation of the given arguments   with an application json mimetype    To mimic this behavior with json dumps you have to add a few extra lines of code   response   make response dumps sample  cls CustomEncoder   response headers  Content-Type      application json  response headers  mimetype      application json  return response   You should also return a dict to fully replicate jsonify s response  So  the entire file will look like this  from flask import make response from json import JSONEncoder  dumps   class CustomEncoder JSONEncoder       def default self  obj           if set   quantize    year    intersection dir obj                return str obj          elif hasattr obj   next                return list obj          return JSONEncoder default self  obj    app route   get reps    methods   GET    def get reps        sample     some text    lt datetime object gt   123      response   make response dumps   result   sample   cls CustomEncoder       response headers  Content-Type      application json      response headers  mimetype      application json      return response

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My solution  with less verbosity  I think    def default o       if type o  is datetime date or type o  is datetime datetime          return o isoformat    def jsondumps o       return json dumps o  default default    Then use jsondumps instead of json dumps  It will print    gt  gt  gt  jsondumps   today   datetime date today        today    2013-07-30      I you want  later you can add other special cases to this with a simple twist of the default method  Example     def default o       if type o  is datetime date or type o  is datetime datetime          return o isoformat       if type o  is decimal Decimal          return float o

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This Q repeats time and time again - a simple way to patch the json module such that serialization would support datetime     import json import datetime  json JSONEncoder default   lambda self obj   obj isoformat   if isinstance obj  datetime datetime  else None    Than use json serialization as you always do - this time with datetime being serialized as isoformat   json dumps   created  datetime datetime now       Resulting in     created    2015-08-26T14 21 31 853855     See more details and some words of caution at  StackOverflow  JSON datetime between Python and JavaScript

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My quick  amp  dirty JSON dump that eats dates and everything  json dumps my dictionary  indent 4  sort keys True  default str   default is a function applied to objects that aren t serializable  In this case it s str  so it just converts everything it doesn t know to strings  Which is great for serialization but not so great when deserializing  hence the  quot quick  amp  dirty quot   as anything might have been string-ified without warning  e g  a function or numpy array

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Actually it is quite simple  If you need to often serialize dates  then work with them as strings  You can easily convert them back as datetime objects if needed   If you need to work mostly as datetime objects  then convert them as strings before serializing    import json  datetime  date   str datetime datetime now    print json dumps date    2018-12-01 15 44 34 409085  print type date    lt class  str  gt   datetime obj   datetime datetime strptime date    Y- m- d  H  M  S  f   print datetime obj  2018-12-01 15 44 34 409085 print type datetime obj    lt class  datetime datetime  gt    As you can see  the output is the same in both cases  Only the type is different

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I faced this issue today  I found something called pickle  It s a built-in library for serializing python objects and also load it from a pickle file  The only difference I found between pickle and json is pickle file is a binary file  where as json is a usual text file  And It doesn t cause any issues with datetime objects

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This library superjson can do it  And you can easily custom json serializer for your own Python Object by following this instruction https   superjson readthedocs io index html extend   The general concept is   your code need to locate the right serialization   deserialization method based on the python object  Usually  the full classname is a good identifier   And then your ser   deser method should be able to transform your object to a regular Json serializable object  a combination of generic python type  dict  list  string  int  float  And implement your deser method reversely

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My solution      from datetime import datetime import json  from pytz import timezone import pytz   def json dt serializer obj          JSON serializer  by macm              rsp   dict       if isinstance obj  datetime           rsp  day     obj day         rsp  hour     obj hour         rsp  microsecond     obj microsecond         rsp  minute     obj minute         rsp  month     obj month         rsp  second     obj second         rsp  year     obj year         rsp  tzinfo     str obj tzinfo          return rsp     raise TypeError  Type not serializable     def json dt deserialize obj          JSON deserialize from json dt serializer  by macm              if isinstance obj  str           obj   json loads obj      tzone   timezone obj  tzinfo        tmp dt   datetime obj  year                          obj  month                          obj  day                          hour obj  hour                          minute obj  minute                          second obj  second                          microsecond obj  microsecond        loc dt   tzone localize tmp dt      deserialize   loc dt astimezone tzone      return deserialize       Ok  now some tests     Tests now   datetime now pytz utc     Using this solution rsp   json dt serializer now  tmp   json dt deserialize rsp  assert tmp    now assert isinstance tmp  datetime     True assert isinstance now  datetime     True    using default from json dumps tmp   json dumps datetime now pytz utc   default json dt serializer  rsp   json dt deserialize tmp  assert isinstance rsp  datetime     True    Lets try another timezone eastern   timezone  US Eastern   now   datetime now eastern  rsp   json dt serializer now  tmp   json dt deserialize rsp   print tmp    2015-10-22 09 18 33 169302-04 00  print now    2015-10-22 09 18 33 169302-04 00    Wow  Works  assert tmp    now

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Here is my solution  import json   class DatetimeEncoder json JSONEncoder       def default self  obj           try              return super   default obj          except TypeError              return str obj   Then you can use it like that  json dumps dictionnary  cls DatetimeEncoder

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Simple  str date variable here

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I got the same error message while writing the serialize decorator inside a Class  with sqlalchemy  So instead of    Class Puppy Base                property     def serialize self           return    id  self id                    date birth  self date birth                                            I  simply borrowed jgbarah s idea of using isoformat   and appended the original value with isoformat    so that it now looks like                                           date birth  self date birth isoformat

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If you are on both sides of the communication you can use repr   and eval   functions along with json   import datetime  json  dt   datetime datetime now   print  This is now      format dt    dt1   json dumps repr dt   print  This is serialised      format dt1    dt2   json loads dt1  print  This is loaded back from json      format dt2    dt3   eval dt2  print  This is the same object as we started      format dt3    print  Check if they are equal      format dt    dt3     You shouldn t import datetime as  from datetime import datetime   since eval will complain  Or you can pass datetime as a parameter to eval  In any case this should work

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Updated for 2018  The original answer accommodated the way MongoDB  date  fields were represented as      date   1506816000000   If you want a generic Python solution for serializing datetime to json  check out  jjmontes  answer for a quick solution which requires no dependencies     As you are using mongoengine  per comments  and pymongo is a dependency  pymongo has built-in utilities to help with json serialization  http   api mongodb org python 1 10 1 api bson json util html  Example usage  serialization    from bson import json util import json  json dumps anObject  default json util default    Example usage  deserialization    json loads aJsonString  object hook json util object hook      Django  Django provides a native DjangoJSONEncoder serializer that deals with this kind of properly   See https   docs djangoproject com en dev topics serialization  djangojsonencoder  from django core serializers json import DjangoJSONEncoder  return json dumps    item    sort keys True    indent 1    cls DjangoJSONEncoder     One difference I ve noticed between DjangoJSONEncoder and using a custom default like this   import datetime import json  def default o       if isinstance o   datetime date  datetime datetime            return o isoformat    return json dumps    item    sort keys True    indent 1    default default     Is that Django strips a bit of the data     last login    2018-08-03T10 51 42 990     DjangoJSONEncoder    last login    2018-08-03T10 51 42 990239     default   So  you may need to be careful about that in some cases

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You should use  strftime   method on  datetime now   method to making it as a serializable method   Here s an example   from datetime import datetime  time dict     time   datetime now   strftime   Y- m- dT H  M  S    sample dict     a   1   b   2  sample dict update time dict  sample dict   Output   Out 0     a   1   b   2   time    2017-10-31T15 16 30

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I have just encountered this problem and my solution is to subclass json JSONEncoder   from datetime import datetime import json  class DateTimeEncoder json JSONEncoder       def default self  o           if isinstance o  datetime               return o isoformat            return json JSONEncoder default self  o    In your call do something like  json dumps yourobj  cls DateTimeEncoder  The  isoformat   I got from one of the answers above

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Try this one with an example to parse it      usr bin env python  import datetime import json  import dateutil parser    pip install python-dateutil   class JSONEncoder json JSONEncoder        def default self  obj           if isinstance obj  datetime datetime               return obj isoformat           return super JSONEncoder  self  default obj    def test        dts             datetime datetime now            datetime datetime now datetime timezone -datetime timedelta hours 4             datetime datetime utcnow            datetime datetime now datetime timezone utc             for dt in dts          dt isoformat   json loads json dumps dt  cls JSONEncoder           dt parsed   dateutil parser parse dt isoformat          assert dt    dt parsed         print f  dt    dt isoformat    dt parsed              2018-07-22 02 22 42 910637  2018-07-22T02 22 42 910637  2018-07-22 02 22 42 910637           2018-07-22 02 22 42 910643-04 00  2018-07-22T02 22 42 910643-04 00  2018-07-22 02 22 42 910643-04 00           2018-07-22 06 22 42 910645  2018-07-22T06 22 42 910645  2018-07-22 06 22 42 910645           2018-07-22 06 22 42 910646 00 00  2018-07-22T06 22 42 910646 00 00  2018-07-22 06 22 42 910646 00 00   if   name         main         test

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The simplest way to do this is to change the part of the dict that is in datetime format to isoformat  That value will effectively be a string in isoformat which json is ok with   v dict   version dict   v dict  created at     v dict  created at   isoformat

[python] How to overcome "datetime.datetime not JSON serializable"?

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