Problem with promisses

[mhhf]

I have difficulties to work with Promises:

Every snipped is run in the browser truffle(v0.0.13) env with a fresh chain(testrpc) and contract deployment.
I use the Coin Contract from the Solidity Tutorial.

The following web3 code works well:

a = web3.eth.accounts[0];
C = web3.eth.contract(Coin.abi);
c = C.at( Coin.deployed_address );
c.mint(a,42);
c.queryBalance( a ); // BigNumber(42)  

but the following pudding code never return its promise:

a = web3.eth.accounts[0]
c = Coin.at( Coin.deployed_address );
c.mint( a, 42 ).then( function() {
  c.queryBalance(a)
  .then( function( v ){ 
    console.log( v ); // never gets called
  });
})

The code works well until the correct balance(42) is received via rpc.
Then suddenly every second the following rpc request is send:

{"jsonrpc":"2.0","method":"eth_getTransactionByHash","params":["42"],"id":5}

with following response

{"error": {"message": "Invalid parameters.", "code": -32602}, "jsonrpc": "2.0", "id": 5}

where to go from here?

[tcoulter]

Hi @mhhf. Try this for me:

a = web3.eth.accounts[0]
c = Coin.at( Coin.deployed_address );
c.mint( a, 42 ).then( function() {
  return c.queryBalance(a);
}).then( function( v ){ 
  console.log( v ); // should get called
});

If you return a promise within a promise's handler, it will continue executing that promise chain. So in this case, v will be the return value from c.queryBalance(a); (v should be a transaction hash since it looks like queryBalance is a transaction). Make sense?

[tcoulter]

Edited the comment above; lots of typos.

[mhhf]

Works like a charm!

I should have read about promises, d'oh!

[tcoulter]

Cheers! Let me know if you have anymore questions!