Error when retrieving the instance of a deployed contract

Question

I have developed a EnergyExchange DApp in the Ganache local network with React that consist of one main contract "EnergyExchange". This main contract has a function to deploy new Agent contracts.

So what I do is to store the deployed agents contracts in a mapping so later on when I want to interact with them I call the next function:

let contractInstance = await this.getAgentInstance();

The detail of the function can be seen here:

async getAgentInstance(){
  var AgentContract = web3.eth.contract([
    {
      "inputs": [
        {
          "name": "_agentAddress",
          "type": "address"
        },
        {
          "name": "_agentID",
          "type": "uint256"
        },
        {
          "name": "_agentCreationDate",
          "type": "uint256"
        },
        {
          "name": "_agentAvailableEnergyToSell",
          "type": "uint256"
        },
        {
          "name": "_exchangeAddress",
          "type": "address"
        }
      ],
      "payable": false,
      "stateMutability": "nonpayable",
      "type": "constructor"
    },
    {
      "anonymous": false,
      "inputs": [
        {
          "indexed": false,
          "name": "a",
          "type": "uint256"
        }
      ],
      "name": "onAvailableEnergyToSellUpdated",
      "type": "event"
    },
    {
      "constant": false,
      "inputs": [
        {
          "name": "_agentAvailableEnergyToSell",
          "type": "uint256"
        }
      ],
      "name": "updateAvailableEnergyToSell",
      "outputs": [],
      "payable": false,
      "stateMutability": "nonpayable",
      "type": "function"
    },
    {
      "constant": true,
      "inputs": [],
      "name": "getAgentDetails",
      "outputs": [
        {
          "name": "",
          "type": "address"
        },
        {
          "name": "",
          "type": "uint256"
        },
        {
          "name": "",
          "type": "uint256"
        },
        {
          "name": "",
          "type": "uint256"
        }
      ],
      "payable": false,
      "stateMutability": "view",
      "type": "function"
    },
    {
      "constant": false,
      "inputs": [
        {
          "name": "_pricePerUnit",
          "type": "uint256"
        },
        {
          "name": "_unit",
          "type": "uint256"
        }
      ],
      "name": "addSellOrder",
      "outputs": [],
      "payable": false,
      "stateMutability": "nonpayable",
      "type": "function"
    },
    {
      "constant": true,
      "inputs": [],
      "name": "getSellOffers",
      "outputs": [
        {
          "name": "",
          "type": "uint256[]"
        },
        {
          "name": "",
          "type": "address[]"
        },
        {
          "name": "",
          "type": "uint256[]"
        },
        {
          "name": "",
          "type": "uint256[]"
        },
        {
          "name": "",
          "type": "uint256[]"
        },
        {
          "name": "",
          "type": "bool[]"
        }
      ],
      "payable": false,
      "stateMutability": "view",
      "type": "function"
    },
    {
      "constant": false,
      "inputs": [
        {
          "name": "_sellOrderId",
          "type": "uint256"
        }
      ],
      "name": "cancelAddedSellOrder",
      "outputs": [],
      "payable": false,
      "stateMutability": "nonpayable",
      "type": "function"
    },
    {
      "constant": false,
      "inputs": [
        {
          "name": "_sellOrderId",
          "type": "uint256"
        },
        {
          "name": "_sellerAddress",
          "type": "address"
        }
      ],
      "name": "buyEnergy",
      "outputs": [],
      "payable": true,
      "stateMutability": "payable",
      "type": "function"
    }
  ]);
  return await AgentContract.at(this.state.agentInstance);
};

That function returns the specific agent instance associated to the account is being used in the browser with metamask. See below the console.log of the instance:

As you can see, the getAgentInstance() function is returning the desired output.

The error appears when trying to interact with the deployed contract through the retrieved instance. For example when calling a get function:

async agentGetDetails(){
  
  
  let contractInstance = await this.getAgentInstance();
  console.log(contractInstance);
  let details = await contractInstance.getAgentDetails({from:this.state.account});

  

  console.log('function get agentdetails executed');
  }

And here it goes the solidity function we are calling:

function getAgentDetails() public view isOwner returns(address,uint,uint,uint){
    return (agentAddress,agentID,agentCreationDate,agentAvailableEnergyToSell);
    
}

The error that i get is detailed next:

Any ideas of what is happening? I already tested the contract and all its functions in both Remix and Truffle-test.

Also if I add an error handling to the function like this:

let details = await contractInstance.getAgentDetails.call({from:this.state.account},function(error,result){
      console.log("error when executing the function",result);
    });
    

It is weird because i receive the expected output as an error in the result but in a weird format.(note the Xs):

Thanks

Answer 1

web3.eth.Contract() takes a capital C at Contract.

And maybe try with this syntax :

getAgentInstance() {
  return new web3.eth.Contract(
    [
      /* JSON-interface of the Agent contract
        ...
      */
    ],
    this.state.agentInstance // supposing that you store the address of the instance you want to access there.
  );
}