Check if key exists and iterate the JSON array using Python

Question

I have a bunch of JSON data from Facebook posts like the one below     from     id    8    name    Mary Pinter     message    How ARE you     comments     count   0    updated time    2012-05-01    created time    2012-05-01    to     data      id    1543    name    Honey Pinter       type    status    id    id 7     The JSON data is semi-structured and all is not the same   Below is my code   import json   str      from     id    8    name    Mary Pinter     message    How ARE you     comments     count   0    updated time    2012-05-01    created time    2012-05-01    to     data      id    1543    name    Honey Pinter       type    status    id    id 7    data   json loads str   post id   data  id   post type   data  type   print post id  print post type   created time   data  created time   updated time   data  updated time   print created time  print updated time   if data get  application        app id   data  application   get  id   0      print app id  else      print  null     if data get  to         This is the part I am not sure how to do   Since it is in the form  to     data     id           I want the code to print the to id as 1543 else print  null   I am not sure how to do this

User · Answer

jsonData        from     id    8    name    Mary Pinter     message    How ARE you     comments     count   0    updated time    2012-05-01    created time    2012-05-01    to     data      id    1543    name    Honey Pinter      name    Joe Schmoe       type    status    id    id 7       def getTargetIds jsonData       data   json loads jsonData      for dest in data  to    data            print  to id    dest get  id    null      Try it    gt  gt  gt  getTargetIds jsonData  to id  1543 to id  null   Or  if you just want to skip over values missing ids instead of printing  null    def getTargetIds jsonData       data   json loads jsonData      for dest in data  to    data            if  id  in to id              print  to id    dest  id      So    gt  gt  gt  getTargetIds jsonData  to id  1543   Of course in real life  you probably don t want to print each id  but to store them and do something with them  but that s another issue

User · Answer

It is a good practice to create helper utility methods for things like that so that whenever you need to change the logic of attribute validation it would be in one place  and the code will be more readable for the followers   For example create a helper method  or class JsonUtils with static methods  in json utils py   def get attribute data  attribute  default value       return data get attribute  or default value   and then use it in your project   from json utils import get attribute  def my cool iteration func data        data to   get attribute data   to   None      if not data to          return      data to data   get attribute data to   data           for item in data to data          print  The id is   s    get attribute item   id    null      IMPORTANT NOTE   There is a reason I am using data get attribute  or default value instead of simply data get attribute  default value      my key   None  get  my key    nothing     returns None   my key   None  get  my key   or  nothing    returns  nothing    In my applications getting attribute with value  null  is the same as not getting the attribute at all  If your usage is different  you need to change this

User · Answer

I wrote a tiny function for this purpose  Feel free to repurpose   def is json key present json  key       try          buf   json key      except KeyError          return False      return True

User · Answer

If all you want is to check if key exists or not  h     a   1   b  in h   returns False   If you want to check if there is a value for key  h get  b     returns None   Return a default value if actual value is missing  h get  b    Default value

User · Answer

You can use a try-except try     print str to id  except AttributeError    Not a Retweet    print  null

User · Answer

import json  jsonData        from     id    8    name    Mary Pinter     message    How ARE you     comments     count   0    updated time    2012-05-01    created time    2012-05-01    to     data      id    1543    name    Honey Pinter       type    status    id    id 7       def getTargetIds jsonData       data   json loads jsonData      if  to  not in data          raise ValueError  No target in given data       if  data  not in data  to            raise ValueError  No data for target        for dest in data  to    data            if  id  not in dest              continue         targetId   dest  id           print  to id    targetId    Output   In  9   getTargetIds s  to id  1543

User · Answer

if  my data  in my json data           print json dumps my json data  my data

[python] Check if key exists and iterate the JSON array using Python

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