Unpacking return unexpected result

Question

I'm having some issue with the contract read, i have data in format of sp.TMap(string,bytes), im using sp.pack() to get the bytes representation of a sp.TNat in a concrete example for a nat 200 y get as result 05008803, i been trying to decode the data using @TezosTaquito but couldn't get the result expected.

Also trying to replicate the encode of that nat @TezosTaquito don't give me the same bytes gotten from contract.

Using Tzip12 module neither work as expected.

Answer 1

For packing and unpacking michelson values, you can use the @taquito/michel-codec package.

Example:

const { packDataBytes, unpackDataBytes } = require("@taquito/michel-codec");

export function unpackData(bytes, type) {
  return unpackDataBytes({ bytes }, type);
}

export function packData(value, type) {
  return packDataBytes(value, type).bytes;
}

// Packing
packData({ int: 200 }, { prim: 'nat' }) // 05008803

// Unpacking
unpackData("05008803", { prim: "nat" }) // {"int":"200"}

Live example: https://codesandbox.io/s/elastic-cray-e8oviv?file=/src/index.js