TypeChain says the struct array field does NOT exist in my Ballot struct, why?

Question

I am trying to test my voting ballot contract using Hardhat/ethers/TypeChain, but for some reason, the Ballot struct's typescript interface is NOT showing the array of choices struct field I have defined in the smart contract.

Below, is the TypeScript test file that isn't showing the Choice[] choices field in the ballot returned from the ballots mapping.

Here is the entire smart contract code: // SPDX-License-Identifier: MIT pragma solidity ^0.8.0;

contract Voting {

// @dev for voters we need to check address has been approved for voting using mapping
mapping(address => bool) public voters;
// e.g. inflate jewel by 5% - id: 1, string: 5% inflation, votes: (0)
struct Choice {
    uint id;
    string name;
    uint votes;
}
// e.g. Ballot = vote, id: 1, name: jewel inflation, list of choices, end of ballot/time
struct Ballot {
    uint id;
    string name;
    Choice[] choices;
    uint end; 
}
// @dev id of each ballot
mapping(uint => Ballot) public ballots;
uint nextBallotId;
address public admin;
// @dev check if address of voter has already voted for a given ballot
mapping(address => mapping(uint => bool)) public votes;

constructor() {
    admin = msg.sender;
}
// [0xef..., 0xerfdf..]
function addVoters(address[] calldata _voters) onlyAdmin() external {
    for(uint i = 0; i < _voters.length; i++) {
        // e.g. voters[[0xef]] = true 
        voters[_voters[i]] = true;
    }
}

function createBallot(
    string memory name,
    string[] memory _choices,
    uint offset
) public onlyAdmin() {
    // @dev can't assign due to Choices[] array as ballot's data location is STORAGE not MEMORY
    // e.g. Choice[] memory _choices = new ... 
    // ballots[nextBallotId] = Ballot(nextBallotId, name, **_choices**, end)

    // @dev can acccess field of struct that hasn't been created yet
    ballots[nextBallotId].id = nextBallotId;
    ballots[nextBallotId].name = name;
    ballots[nextBallotId].end = block.timestamp + offset;
    
    for(uint i = 0; i < _choices.length; i++) {
        ballots[nextBallotId].choices.push(Choice(i, _choices[i],  0));
    }
    nextBallotId++;

}

function vote(uint ballotId, uint choiceId) external {
    require(voters[msg.sender] = true, 'only voters can vote');
    require(votes[msg.sender][ballotId] == false, 'voter can only vote once per ballot');
    require(block.timestamp < ballots[ballotId].end, 'can only vote after ballot end date');
    votes[msg.sender][ballotId] = true;
    ballots[ballotId].choices[choiceId].votes++;

}

function results(uint ballotId) 
    view 
    external
    returns(Choice[] memory) {
        require(block.timestamp >= ballots[ballotId].end, 'cannot see the ballot result before ballot end');
        return ballots[ballotId].choices;
    }


modifier onlyAdmin() {
    require(msg.sender == admin, 'only admin');
    _;
}

}

Answer 1

Attention, in your code that you posted you haven't specify ballots variable with public visibility.

You must to specify the public visibility of ballots state variable. In your case change this:

mapping(uint => Ballot) ballots;

and replace it with:

mapping(uint => Ballot) public ballots;

When you define public, the compiler generate automatically generate getter function for variable which allow to view the values or handle it.

More information about visibility here.