How to merge two json string in Python

Question

I recently started working with Python and I am trying to concatenate one of my JSON String with existing JSON String  I am also working with Zookeeper so I get the existing json string from zookeeper node as I am using Python kazoo library     gets the data from zookeeper data  stat   zk get some znode path  jsonStringA   data decode  utf-8     if I print jsonStringA it gives me like this -    error 1395946244342   valueA   error 1395952003   valueB     But if I do print json loads jsonString  then it prints out like this -   u error 1395946244342   u valueA   u error 1395952003   u valueB     Here jsonStringA will have my existing JSON String  Now I have another key-value pair which I need to add in the exiting jsonStringA -  Below is my Python code -    gets the data from zookeeper data  stat   zk get some znode path  jsonStringA   data decode  utf-8    timestamp in ms    error   str int round time time     1000    node     pp tf test v1  a b c d   node split      1   host info    h1  local dc    dc3  step    step2    My existing jsonStringA will be like this after extracting from zookeeper -    error 1395946244342   valueA   error 1395952003   valueB     Now I need to append this key-value pair in the jsonStringA -    timestamp in ms   Error Occured on machine   host info   in datacenter    local dc    on the    step    of process    c      So in short I need to merge below key-value pair -   error 1395952167   Error Occured on machine h1 in datacenter dc3 on the step2 of process test    So final JSON String will look like this -    error 1395946244342   valueA   error 1395952003   valueB   error 1395952167   Error Occured on machine h1 in datacenter dc3 on the step2 of process test     Is this possible to do

User · Answer

To append key-value pairs to a json string, you can use dict.update: dictA.update(dictB).

For your case, this will look like this:

dictA = json.loads(jsonStringA)
dictB = json.loads('{"error_1395952167":"Error Occured on machine h1 in datacenter dc3 on the step2 of process test"}')

dictA.update(dictB)
jsonStringA = json.dumps(dictA)

Note that key collisions will cause values in dictB overriding dictA.

User · Answer

What do you mean by merging  JSON objects are key-value data structure  What would be a key and a value in this case  I think you need to create new directory and populate it with old data   d      d  new key     jsonStringA  lt key that you did not mention here gt                       jsonStringB  timestamp in ms     Merging method is obviously up to you

User · Answer

Assuming a and b are the dictionaries you want to merge   c    key  value for  key  value  in  a items     b items       To convert your string to python dictionary you use the following   import json my dict   json loads json str      Update  full code using strings     test cases for jsonStringA and jsonStringB according to your data input jsonStringA      error 1395946244342   valueA   error 1395952003   valueB    jsonStringB      error  d   Error Occured on machine  s in datacenter  s on the  s of process  s       timestamp number  host info  local dc  step  c     now we have two json STRINGS import json dictA   json loads jsonStringA  dictB   json loads jsonStringB   merged dict    key  value for  key  value  in  dictA items     dictB items        string dump of the merged dict jsonString merged   json dumps merged dict    But I have to say that in general what you are trying to do is not the best practice  Please read a bit on python dictionaries      Alternative solution   jsonStringA   get my value as string from somewhere   errors dict   json loads jsonStringA   new error str    Error Ocurred in datacenter  s blah for step  s blah     datacenter  step  new error key    error  d     timestamp number   errors dict new error key    new error str    and if I want to export it somewhere I use the following write my dict to a file as string json dumps errors dict     And actually you can avoid all these if you just use an array to hold all your errors

User · Answer

You can load both json strings into Python Dictionaries and then combine  This will only work if there are unique keys in each json string  import json  a   json loads jsonStringA  b   json loads jsonStringB  c   dict a items     b items      or c    dict a    b

User · Answer

As of Python 3 5  you can merge two dicts with   merged      dictA    dictB     https   www python org dev peps pep-0448    So   jsonMerged      json loads jsonStringA     json loads jsonStringB   asString   json dumps jsonMerged    etc

User · Answer

Merging json objects is fairly straight forward but has a few edge cases when dealing with key collisions  The biggest issues have to do with one object having a value of a simple type and the other having a complex type  Array or Object   You have to decide how you want to implement that  Our choice when we implemented this for json passed to chef-solo was to merge Objects and use the first source Object s value in all other cases   This was our solution   from collections import Mapping import json   original   json loads jsonStringA  addition   json loads jsonStringB   for key  value in addition iteritems        if key in original          original value   original key          if isinstance value  Mapping  and isinstance original value  Mapping               merge dicts original value  value          elif not  isinstance value  Mapping  or                    isinstance original value  Mapping                original key    value         else              raise ValueError  Attempting to merge    with value     format                  key  original value       else          original key    value   You could add another case after the first case to check for lists if you want to merge those as well  or for specific cases when special keys are encountered

[python] How to merge two json string in Python?

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