Encoder

Convert data between formats

The encoder library converts Lua data to transport formats — JSON for APIs, base64 for files, hex for hashes.

Function reference

encoder.json — The most used function

-- Prepare data for an HTTP POST
local payload = encoder.json({
    name = "John",
    items = { 1, 2, 3 },
    metadata = { source = "wapka" }
})
-- → '{"name":"John","items":[1,2,3],"metadata":{"source":"wapka"}}'

-- Send to an external API
http.post("https://api.example.com/webhook", {
    body = payload,
    headers = { ["content-type"] = "application/json" }
})

Uses JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES — Unicode stays readable, slashes stay clean.

encoder.base64 — Encode for transport

-- Encode binary data for JSON APIs
local encoded = encoder.base64("binary content here")
-- → "YmluYXJ5IGNvbnRlbnQgaGVyZQ=="

-- Use as part of a data URI
local image_data = encoder.base64(raw_image_bytes)
local src = "data:image/png;base64," .. image_data

encoder.hex — Binary to hex

-- Common in hashing and crypto workflows
local hex = encoder.hex("hello")
-- → "68656c6c6f"

-- Each byte becomes 2 hex characters
print(#hex)  -- 10 (5 bytes → 10 hex chars)

encoder.base36 — Compact encoding

-- Shorter than hex, safe for filenames
local encoded = encoder.base36("test")
-- → "wanek4"

encoder.rot13 — Simple obfuscation

-- Not security — just hides text from casual reading
encoder.rot13("hello")  → "uryyb"
encoder.rot13("uryyb")  → "hello"  -- symmetric

Practical: webhook notification

app:post("/notify", function(ctx)
    local event = {
        type = "user.created",
        user_id = 42,
        timestamp = os.date("!%Y-%m-%dT%H:%M:%SZ")
    }

    local body = encoder.json(event)
    local sig = hash.hmac(WEBHOOK_SECRET, body)

    local res = http.post("https://api.partner.com/webhooks", {
        body = body,
        headers = {
            ["content-type"] = "application/json",
            ["x-signature"] = sig
        }
    })

    return { sent = res.status == 200 }
end)

Next: Decoder — parse incoming data.