How to extract a key value pair from a nested dictionary and output it in json

Question

I am extracting part of a dictionary with

with open(output_filename, "w") as outfile:
    json.dump(data['metadata'], outfile)

So that I get the value of 'metadata' and none of the key value pairs before. How do I modify it so I also get the key itself ('metadata') to appear in the output before the value? I tried this

for key in my_dict.keys():
   if key is "metadata":
       val = my_dict[key]

and then using json.dump(val, outfile) but that created an error global name val is not defined (I defined it as a global variable earlier to try to fix an earlier error message.) I can't use just "data" itself because there is a key value pair in data that I want to exclude.

Answer 1

with open(output_filename, "w") as outfile:
    json.dump({'metadata': data['metadata']} , outfile)