Python 3.4+ Scripting regarding to Batch Editing JSON and Saving them

Question

I'm trying to Batch Edit all JSON files within a folder, and saving each of them as new JSON all at once, instead of doing each one.

   def new_json(filename):
    with open(filename, 'r+') as f:
        json_data = json.load(f)
        somefunction()
        f.seek(0)
        base, ext = os.path.splitext(filename)
        out_file = open(base + '_expand' + ext, 'w')
        json.dump(room_data, out_file, indent=4)

   def batchRun(foldername):
        for f in os.listdir(foldername):
             new_json(f)

   folder = 'testing'
   batchRun(folder)

When I try to run the batchRun function, it gives me an error

    Traceback (most recent call last):
      File "<pyshell#12>", line 1, in <module>
      batchRun(folder)
      File "<pyshell#8>", line 3, in batchRun
      new_json(f)
      File "<pyshell#6>", line 2, in new_json
      with open(filename, 'r+') as f:
      FileNotFoundError: [Errno 2] No such file or directory: 'simple_json.txt'

And I know for sure simple_json.txt and other files are within that folder that I defined, so I'm not sure what's happening.

Answer 1

os.listdir gives you a list of file names , not file paths. You can use os.path.join to get the full file path:

def batchRun(foldername):
    for f in os.listdir(foldername):
         new_json(os.path.join(foldername, f))