jq flatten json recursively

flatten-objects.jq

# concise version:
# 'map(def flatten($prefix): . as $in | reduce keys[] as $key ({}; . + (if ($in[$key] | type) == "object" then $in[$key] | flatten(($prefix + $key + ".")) else {($prefix + $key): $in[$key]} end));flatten(""))'

# unwrapped for readabiliy:
map(
    # Recursive function to flatten an object
    def flatten($prefix):
        . as $in
        | reduce keys[] as $key (
            {}; . + (
                # Check if the value is an object and needs further flattening
                if ($in[$key] | type) == "object" then
                    $in[$key] | flatten(($prefix + $key + "."))
                # If it's not an object, add it to the output
                else
                    {($prefix + $key): $in[$key]}
                end
            )
        );
    # Apply the function to each item in the array
    flatten("")
)