Identify .json files with empty arrays?

Question

I have a folder with multiple .json files. There are certain files with empty arrays, Sample file :

{
"WarehouseActivity": []
}

The file has no other data apart from the one shown above.

I need to identify these files and move them into a error folder. Any suggestions on how to go about this would be great.

Thanks, Kavin

Answer 1

mkdir -p error_folder &&
for json in ./*.json; do
    if jq -e '.. | select(type == "array" and length == 0)' "$json" >/dev/null
    then
        mv "$json" error_folder/
    fi
done

This is more or less the same approach as Roman took in his answer, but uses a different jq expression.

The expression ..|select(type == "array" and length == 0) will recurse the full JSON structure and select all bits of it that are zero-length arrays (anywhere, at any depth).

If the select() is successful, then jq will exit with a zero exit status (success), which means that the JSON document contains an empty array somewhere (or the file is totally empty). This triggers a moving of the document to error_folder in the script.

---

From comments below it is clear that the user is only interested in the WarehouseActivity array.

My code with a modified jq expression:

mkdir -p error_folder &&
for json in ./*.json; do
    if jq -e '.. | .WarehouseActivity? | select(type == "array" and length == 0)' "$json" >/dev/null
    then
        mv "$json" error_folder/
    fi
done

Answer 2

Jq would be the right tool for processing/analyzing JSON data:

for f in *.json; do
    if jq -e 'keys_unsorted as $keys
              | ($keys | length == 1) 
                and .[($keys[0])] == []' "$f" > /dev/null; then
        mv "$f" error_dir/
    fi
done