measureMsgPack()
Description
measureMsgPack() computes the length of the MessagePack document that serializeMsgPack() produces.
This function is handy to fill the Content-Length header in an HTTP message.
Signature
size_t measureMsgPack(const JsonDocument& doc);
Arguments
doc: the JsonDocument to serialize (in fact, you can also use a JsonArray, a JsonObject, or a JsonVariant).
Return value
The number of bytes that serializeMsgPack() produces.
Example
// Send headers
client.println("Content-Type: application/msgpack");
client.print("Content-Length: ");
client.println(measureMsgPack(doc));
// Terminate headers
client.println();
// Send body
serializeMsgPack(doc, client);