Problem with decoding complex types returned from contract function

[adammalczewski]

Description

I am trying to call a method from blockchain contract which returns single value of type tuple[]:

    const web3 = new Web3(ProviderAddress);
    const contract = new web3.eth.Contract(Web3ContractABI, ContractAddress);
    const users = await contract.methods.getAllUsers().call();

part of ABI JSON regarding getAllUsers function:

  {
    'constant': true,
    'inputs': [],
    'name': 'getAllUsers',
    'outputs': [
      {
        'components': [
          {
            'name': 'idUser',
            'type': 'address'
          },
          {
            'name': 'param1',
            'type': 'int256'
          },
          {
            'name': 'param2',
            'type': 'int256'
          }
        ],
        'name': '',
        'type': 'tuple[]'
      }
    ],
    'payable': false,
    'stateMutability': 'view',
    'type': 'function'
  },

on remix.ethereum.org when i call the function i get:

0: tuple(address,int256,int256)[]: 0xf2D38fC631d4FCFbAeDB274D2b95C436ab75a1B4,0,0

Expected behavior

users should be [["0xf2D38fC631d4FCFbAeDB274D2b95C436ab75a1B4", ...]]

Actual behavior

users is [[]]

Additional notes

I have already found the source of this error, will create PR soon.

Versions

• web3.js: 1.0.0-beta.51
• nodejs: 10.14.2
• ethereum node - instance: Geth/v1.8.16-stable-477eb093/linux-amd64/go1.11, private network

[nivida]

Web3.js is using the AbiCoder of ethers.js. Could you please open an issue in the ethers.js repository?

[adammalczewski]

Web3.js is using the AbiCoder of ethers.js. Could you please open an issue in the ethers.js repository?

I am confident that the problem lies on the Web3.js side and as I have written i have already fixed this, AbiCoder from ethers.js works correctly.

[nivida]

Can you explain to me closer why it should be a problem with Web3.js?

[adammalczewski]

Method afterExecution in class CallContractMethod in web3-eth-contract/src/methods/CallContractMethod.js passes string to AbiCoder's method decodeParameter instead of AbiOutput and because of this, information about tuple's components is lost.

Now it's:

return this.abiCoder.decodeParameter(outputs[0].type, response);

instead of:

return this.abiCoder.decodeParameter(outputs[0], response);

I fixed this in my fork already but I'm still investigating the use of decodeParameter method because I can see 'type' field from AbiOutput instance being passed to this function on one other occasion.

[nivida]

Thanks! I've missed that case. Will fix and release it asap.