JSON for Bot Builders: Payloads, Validation and Common Mistakes

A compact JSON guide for bot builders covering objects, types, nested data, validation, serialization and webhook mistakes.

JSON is a data format, not executable code

JSON is useful because nearly every webhook and REST API can send or receive it. It supports objects, arrays, strings, numbers, booleans and null. It does not support comments, Python tuples, JavaScript functions or trailing commas.

{
  "event_id": "abc-123",
  "symbol": "BTCUSD",
  "action": "buy",
  "size": 0.01,
  "meta": {"source": "tradingview", "version": 1},
  "tags": ["breakout", "demo"],
  "dry_run": true
}

Strings versus numbers

"0.01" is a string; 0.01 is a number. Many integrations fail because the producer and receiver disagree about types. Decide a schema and enforce it before the event can reach execution code.

def validate_event(d):
    if not isinstance(d.get("event_id"), str):
        return False, "event_id_not_string"
    if d.get("action") not in {"buy", "sell", "close"}:
        return False, "bad_action"
    if not isinstance(d.get("size"), (int, float)):
        return False, "bad_size"
    return True, "ok"

Serialization

In Python, json.dumps() turns Python data into JSON text and json.loads() parses JSON text. The requests library can usually send a JSON body using the json=payload argument, which also sets an appropriate content type.

Common mistakes

• Using single quotes around JSON keys.
• Leaving a trailing comma after the last field.
• Assuming missing and null mean the same thing.
• Accepting arbitrary extra fields without deciding whether they are safe.
• Putting passwords or API keys inside a webhook payload.
• Logging the full payload when it contains secrets.