Python - update item in an existing json file -

i want update float values inside json file, structured this:

{"starbucks": {"roads": 1.0, "pyramid song": 1.0, "go alone": 1.0}} 

so whenever generate existing playlist, exact same items, increment key values +1.0.

i have file opened 'append' option

with open('pre_database/playlist.json', 'a') f:      if os.path.exists('pre_database/playlist.json'):          #update json here      json.dump(playlist,f) 

but 'a' method append dictionary json, , generate parsing problems later on.

likewise, if use 'w' method, overwrite file entirely.

what best solution updating values?

you open file in r+ mode (opens file both reading , writing), read in json content, seek start of file, truncate , rewrite modified dictionary file:

if os.path.exists('pre_database/playlist.json'):     open('pre_database/playlist.json', 'r+') f:          playlist = json.load(f)          # update json here          f.seek(0)          f.truncate()          json.dump(playlist, f)