prepareTransaction method

Future<TransactionRequest> prepareTransaction(TransactionRequest request)

Prepares a transaction by filling in missing fields.

Implementation

Future<TransactionRequest> prepareTransaction(
    TransactionRequest request) async {
  var tx = request;

  // Set chain ID
  if (tx.chainId == null) {
    tx = tx.copyWith(chainId: chain.chainId);
  }

  // Set nonce
  if (tx.nonce == null) {
    final nonce = await getTransactionCount(address, 'pending');
    tx = tx.copyWith(nonce: nonce);
  }

  // Set gas limit
  if (tx.gasLimit == null) {
    final gasLimit = await estimateGas(_toCallRequest(tx));
    // Add 20% buffer
    tx = tx.copyWith(
      gasLimit: gasLimit * BigInt.from(120) ~/ BigInt.from(100),
    );
  }

  // Set gas price / fee
  if (tx.type == TransactionType.legacy) {
    if (tx.gasPrice == null) {
      tx = tx.copyWith(gasPrice: await getGasPrice());
    }
  } else {
    if (tx.maxFeePerGas == null || tx.maxPriorityFeePerGas == null) {
      final feeData = await getFeeData();
      tx = tx.copyWith(
        maxFeePerGas: tx.maxFeePerGas ?? feeData.maxFeePerGas,
        maxPriorityFeePerGas:
            tx.maxPriorityFeePerGas ?? feeData.maxPriorityFeePerGas,
      );
    }
  }

  return tx;
}