JSON_EMPTY_ARRAY

JSON_EMPTY_ARRAY is a global sentinel value that serializes as [] in JSON output. Use it when you need an empty array instead of the default empty object {}.

Usage

Assign JSON_EMPTY_ARRAY to any table key to force an empty JSON array:

-- Without sentinel: empty table becomes {}
json_encode({ items = {} })             -- '{"items":{}}'

-- With sentinel: force empty array
json_encode({ items = JSON_EMPTY_ARRAY })  -- '{"items":[]}'

Server responses

get.data = function(self)
    return {
        status = 200,
        body = {
            items = JSON_EMPTY_ARRAY,
            meta = {}  -- this stays as {}
        },
    }
end

With array parameter

The array parameter on json_encode works independently. JSON_EMPTY_ARRAY always produces [] regardless of the flag:

json_encode(JSON_EMPTY_ARRAY)          -- "[]"
json_encode(JSON_EMPTY_ARRAY, false)   -- "[]"
json_encode(JSON_EMPTY_ARRAY, true)    -- "[]"

Do not mutate

Adding keys to JSON_EMPTY_ARRAY will change its serialization behavior. Treat it as immutable.

See Also

• json_encode - Encode Lua value to JSON string
• json_decode - Decode JSON string to Lua value