detect key conflict in a JSON file

Question

How can you detect if a key is duplicated in a JSON file? Example:

{
 "something": [...],
 ...
 "something": [...]
}

I have a growing JSON file that I edit manually and it might happen that I repeat a key. If this happens, I would like to get notified. Currently the value of the second key silently overwrites the value of the first.

Do you know about a command line JSON validator?

Answer 1

1. The real answer here is that JSON is probably not the best choice for large files that get hand-edited. For data that you intend to hand-edit a lot, YAML might be a better choice.

2. Yeah, that's what I would expect. http://www.json.org/ is mute on the question of what to do with duplicate keys, but I would be quite surprised to discover any implementation which behaved differently.

3. All JSON implementations validate their input. You are assuming that having duplicate keys is "invalid". I would think it falls more into the category of "undefined behavior".

Answer 2

You can pass an appropriate object_pairs_hook function to json.load():
http://docs.python.org/2/library/json.html#repeated-names-within-an-object
http://docs.python.org/2/library/json.html#json.load