How to make a estimated transaction fee preview

mattiaferrariiiii · September 27, 2023, 10:17am

I’m creating a broser wallet. The feature that I’m writing needs to obtain the estimated transaction fee as the current web wallet is doing.
Screenshot 2023-09-27 at 12.12.03

From what i’m able to see here the fee is being calculated using this.
The feature that i’m implementing needs to calculate the fees only for simple transfers of CCD.
I don’t understand what are that tokenId and contractIndex in my case

github.com

Concordium/concordium-browser-wallet/blob/7adb1cb001786c4ba92282b2a43dfc6535e3e5ca/packages/browser-wallet/src/popup/pages/Account/SendCcd/CreateTransfer.tsx#L101-L126


      
          const fee = useAsyncMemo<FeeResult>(
              async () => {
                  if (chosenToken) {
                      if (validateAccountAddress(recipient)) {
                          return undefined;
                      }
                      try {
                          const energy = await getTokenTransferEnergy(
                              client,
                              address,
                              recipient,
                              chosenToken.tokenId,
                              BigInt(chosenToken.contractIndex)
                          );
                          form.setValue('executionEnergy', energy.execution.toString());
                          return { success: true, value: energy.total };
                      } catch (e) {
                          addToast(t('sendCcd.transferInvokeFailed', { message: (e as Error).message }));
                          return { success: false };
                      }

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abizjak · September 27, 2023, 1:09pm

Simple transfer has a fixed NRG cost of 501 NRG (for transfers without a memo).

You can then get the exchange rate of NRG/CCD by querying chain parameters using GetBlockChainParameters. From this you can compute the cost of the transaction in CCD (estimated).

mattiaferrariiiii · September 27, 2023, 1:15pm

This is the response that i get calling GetBlockChainParameters, what do i have to multiply to 501 ?

abizjak · September 27, 2023, 1:29pm

If you multiply microGTUPerEuro with euroPerEnergy you will get the exchange rate between micro CCD and NRG.

Multiply the NRG cost by that (of course 1 CCD is 1_000_000 microCCD).

mattiaferrariiiii · September 27, 2023, 3:09pm

Ok thanks for the help