How to calculate total fees spent on a Tezos transaction using Taquito?

Question

I am currently working on a project involving Tezos smart contracts, and I'm using Taquito to interact with the Tezos blockchain. I'm trying to calculate the total fees spent on a confirmed transaction, including the baker's fee and the storage cost.

From what I can tell, the result: OperationContentsAndResult object returned when an operation is confirmed contains a fee field (which I assume represents the baker's fee) and a storage_limit field. My current approach is to calculate the total fee as fee + storage_limit * 250 mutez.

However, it feels like I might be reinventing the wheel here. Is there a built-in function or feature in Taquito that allows you to get the total fees (in XTZ) spent on a transaction? If not, is my current approach correct, or is there a better way to calculate this?

Answer 1

For a single operation, I'll suggest go through op.operationResults[0].metadata.balance_updates and op.operationResults[0].metadata.operation_result.balance_updates and add up the change value of the object property contract match the source. This is an example of operationResults for your reference

[
  {
    "kind": "transaction",
    "source": "tz1bwsEWCwSEXdRvnJxvegQZKeX5dj6oKEys",
    "fee": "401",
    "counter": "462459",
    "gas_limit": "1101",
    "storage_limit": "0",
    "amount": "1000000",
    "destination": "tz1VWci3kmwzdwFWiQFzPJKyYLSjtsGarkSh",
    "metadata": {
      "balance_updates": [
        {
          "kind": "contract",
          "contract": "tz1bwsEWCwSEXdRvnJxvegQZKeX5dj6oKEys",
          "change": "-401",
          "origin": "block"
        },
        {
          "kind": "accumulator",
          "category": "block fees",
          "change": "401",
          "origin": "block"
        }
      ],
      "operation_result": {
        "status": "applied",
        "balance_updates": [
          {
            "kind": "contract",
            "contract": "tz1bwsEWCwSEXdRvnJxvegQZKeX5dj6oKEys",
            "change": "-1000000",
            "origin": "block"
          },
          {
            "kind": "contract",
            "contract": "tz1VWci3kmwzdwFWiQFzPJKyYLSjtsGarkSh",
            "change": "1000000",
            "origin": "block"
          }
        ],
        "consumed_milligas": "1000040"
      }
    }
  }
]