Why do all my web3 call methods return null?

Question

I create my contract with the following code:

pragma solidity ^0.5.0;

contract Coin {
    function sayHello() public view returns(bytes32) {
        return "Hello";
    }
}

truffle-config:

module.exports = {
  rpc: {
      host: "localhost",
      port: 8543
  },

  networks: {
    development: {
      host: "127.0.0.1",     // Localhost (default: none)
      port: 8543,            // Standard Ethereum port (default: none)
      network_id: "*",       // Any network (default: none)
      from: "0x3242587c258109ed8722d667501d2116f08e91d1",
      gas: 2100000
    },
  },

  mocha: {
  },

  compilers: {
    solc: {
    }
  }
}

And I migrate it with truffle migrate on my private network and it outputs:

=====================

   Replacing 'Coin'
   ----------------
   > transaction hash:    0x0c9476750b030a7e8ee35678643573e3f941292d3909bbb33a5248185c307774
   > Blocks: 0            Seconds: 0
   > contract address:    0x71A258BE260db4397d5AA32aa7F1BcbB7f03C071
   > block number:        10230
   > block timestamp:     1561343003
   > account:             0x3242587C258109eD8722d667501d2116F08e91D1
   > balance:             9.87546732
   > gas used:            502220
   > gas price:           20 gwei
   > value sent:          0 ETH
   > total cost:          0.0100444 ETH


   > Saving migration to chain.
   > Saving artifacts
   -------------------------------------
   > Total cost:           0.0100444 ETH


Summary
=======
> Total deployments:   2
> Final cost:          0.01527226 ETH

So I deployed it successfully, right?

Then I tried to interact with the contract with the following code

const Web3 = require('web3');
const Web3Accounts = require('web3-eth-accounts');

const web3 = new Web3(Web3.givenProvider || 'http://localhost:8543', null, {});

const coinbase = "0x7bd59507b55d46eb874e6a2f8ee4befa123e414e";
const owner = "0x3242587c258109ed8722d667501d2116f08e91d1";
const abi = /*abi*/
var coin = new web3.eth.Contract(abi, "0x71A258BE260db4397d5AA32aa7F1BcbB7f03C071", 
    {defaultAccount: owner, defaultGasPrice: '20000000'});                   // Contract object

const main = async () => {
    try {
        let reply = await coin.methods.sayHello().call({from: owner});
        console.log(reply);
    }
    catch(error) {
        console.error(`error: ${error}`);
    }
};

main()
    .then(() => { console.log("done"); })
    .catch(err => { console.log("Failed with error: " + err); });

It outputted:

null
done

my envs:

  "dependencies": {
    "web3": "^1.0.0-beta.55",
    "web3-eth-accounts": "^1.0.0-beta.55"
  }

I started my private network with geth --port 3000 --networkid 58343 --nodiscover --datadir=./blkchain --maxpeers=0 --rpc --rpcport 8543 --rpcaddr 127.0.0.1 --rpccorsdomain "*" --rpcapi "eth,net,web3,personal,miner"

I just start in the blockchain world. Please forgive me if this is a dumb question.

Answer 1

Take a look in this line of code. I think it should be coin.methods not coin.method correct me if I'm wrong.

let reply = await coin.method.sayHello().call({from: owner});

Answer 2

I was developing with Truffle, web3, MetaMask and React and was having a similar issue: contract.methods.function().call() kept returning null for returning a private string in a simple contract. My contract object was deployed, I was being shown the methods, ABI looked correct. Very frustrating.

I think what ended up working for me was resetting the MetaMask nonce ( Metamask > Settings > Advanced > Reset Account ) . Meta Mask Docs

If you're running a test blockchain and restart it, you can accidentally confuse MetaMask because it calculates the next nonce based on both the network state and the known sent transactions.

Because I was compiling new contracts and migrating without disconnecting MetaMask, I think it became confused.

I say "maybe" because I basically started a new truffle react box and re implemented everything to make sure I wasn't missing something.

So, it technically could have been a couple things. But I would give this a shot if you are having this issue.