supported selecting asset_id to fee for simple transfer

bitshares/bitshares.py

@@ -409,14 +409,15 @@ def clear(self):
     # -------------------------------------------------------------------------
     # Simple Transfer
     # -------------------------------------------------------------------------
-    def transfer(self, to, amount, asset, memo="", account=None, **kwargs):
+    def transfer(self, to, amount, asset, memo="", fee_asset="1.3.0", account=None, **kwargs):
         """ Transfer an asset to another account.
 
             :param str to: Recipient
             :param float amount: Amount to transfer
             :param str asset: Asset to transfer
             :param str memo: (optional) Memo, may begin with `#` for encrypted
                 messaging
+            :param str fee_asset: Asset to fee
             :param str account: (optional) the source account for the transfer
                 if not ``default_account``
         """
@@ -438,7 +439,7 @@ def transfer(self, to, amount, asset, memo="", account=None, **kwargs):
         )
 
         op = operations.Transfer(**{
-            "fee": {"amount": 0, "asset_id": "1.3.0"},
+            "fee": {"amount": 0, "asset_id": fee_asset},
             "from": account["id"],
             "to": to["id"],
             "amount": {

bitshares/transactionbuilder.py

@@ -282,7 +282,11 @@ def constructTx(self):
                 ops.extend([Operation(op)])
 
         # We no wrap everything into an actual transaction
-        ops = transactions.addRequiredFees(self.bitshares.rpc, ops)
+        if len(ops) == 1 and isinstance(ops[0].op, operations.Transfer):
+            fee_assert_id = ops[0].op.data["fee"].data["asset_id"].Id
+            ops = transactions.addRequiredFees(self.bitshares.rpc, ops, asset_id=fee_assert_id)
+        else:
+            ops = transactions.addRequiredFees(self.bitshares.rpc, ops)
         expiration = transactions.formatTimeFromNow(
             self.expiration or self.bitshares.expiration
         )