web3js encodeABI() is there way to call it asynchronously?

Question

I am working on an ERC827 contract invocation through metamask. For ERC827 transfer method require an additional 'data' argument. Since encodeABI()supports only synchronous invocation, metamask throws error. Is there a way to workaround this problem?

my contract invocation code is something like below.

let erc827_abi = { contract abi}
let service_abi = {contract abi}
var erc827_address = '0x9df5e31a1e5de828254d535d5c9b514d513316e8'
var service_crt_address = '0x1ce94a12f58b0b9b39d0a9f1520878a07d9a72e8' 
var user_address = web3.eth.accounts[0]

const erc827contractInstance = web3.eth.contract(erc827_abi).at(erc827_address);
const servicecontractInstance = web3.eth.contract(service_abi).at(service_crt_address);

//encodeABI() is the call which fails.

const sdata = servicecontractInstance.bookService(args.servicename,user_address,args.customername,args.servicetype,args.value,args.transaction_type,args.account_number).encodeABI(function(error, result){
 if(!error)
     console.log(result);
 else
     console.error(error)
 });
console.log("encoded ABI is",sdata)


erc827contractInstance.transferFrom(user_address,testadd_2,tokensToSend,sdata{from: testadd_2,gas:55000},function (error, result){ //get callback from function which is your transaction key
   if(!error){
        console.log(result);
    } else{
        console.log(error);
    }
});

if encodeABI() is invoked like below it works.

const sdata = servicecontractInstance.bookService(args.servicename,user_address,args.customername,args.servicetype,args.value,args.transaction_type,args.account_number).encodeABI();

But unfortunately metamask does not support this.

appreciate any pointers on resolving this.

Thanks James for your response. Please see the error information. not sure this is the one you are looking for.

inpage.js:1 Uncaught Error: The MetaMask Web3 object does not support synchronous methods like eth_sendTransaction without a callback parameter. See https://github.com/MetaMask/faq/blob/master/DEVELOPERS.md#dizzy-all-async---think-of-metamask-as-a-light-client for details.
    at MetamaskInpageProvider.send (inpage.js:1)
    at s.send (inpage.js:1)
    at n.e [as sendTransaction] (inpage.js:1)
    at u.sendTransaction (inpage.js:1)
    at u.execute (inpage.js:1)
    at HTMLDivElement.<anonymous> (:formatted:1767)
MetamaskInpageProvider.send @ inpage.js:1
s.send @ inpage.js:1
e @ inpage.js:1
u.sendTransaction @ inpage.js:1
u.execute @ inpage.js:1
(anonymous) @ :formatted:1767

Answer 1

In Web3 0.20 (which, if you're using the Web3 injected by MetaMask, is what you're using - BTW, don't do that), myContract.myMethod(params) will make a transaction with those parameters. Then myContract.myMethod(params).encodeABI() would attempt to call encodeABI on the result of that transaction, which is probably not what you want, not least because encodeABI doesn't exist in Web3 0.20.

In Web3 0.20, the equivalent encantation would be myContract.myMethod.getData(params).