Struct within another struct Solidity - solidity

Question

I just started learning solidity and I am working on a bidding contract that allows bidders to bid on a campaign.
I have a struct for campaigns. Bidders have details (address, name), I want to store bidders with their information inside of the campaign. There can be more than one bidder for a campaign
This is my Campaign and Bidder struct
struct Campaign {
uint256 campaignID;
uint256 budget;
uint256 bidCount;
}
struct Bidder {
bool bided;
uint256 bid;
string name;
address bidderAddress;
}
mapping(address => Bidder) public bidders;
Campaign[] public campaigns;
I wrote down a bid function here that takes the index of campaign and bid then populate bidCount.
function bid(uint256 _bidIndex, uint256 _twitterID) public {
require(!bidders[msg.sender].bided);
bidders[msg.sender].bid = _bidIndex;
campaigns[_bidIndex].bidCount += 1;
totalBids += 1;
}
So the Campaign can look something like this (if this is possible)
0: campaignID 1
1: budget 2ETH
2: bidCount 3
3: Bidder {0: name Bidder1, 1: address 0xahaaahha}
{0: name Bidder2, 2: address 0x2334jddd}
Any help will be greatly appreciated. Thanks

Answer 1

According to me, in this case you can use nested mapping into Campaign struct for 'connect' different bids to a single campaign. I created a smart contract ad hoc for your case, you can see it in the following lines:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.13;
contract Auction {
address owner;
constructor() {
owner = msg.sender;
}
struct Campaign {
uint256 campaignID;
uint256 budget;
uint256 bidCount;
mapping(uint => Bidder[]) bidders;
}
struct Bidder {
bool bided;
uint256 bid;
string name;
address bidderAddress;
}
Campaign[] public campaigns;
uint totalCampaign = 0;
modifier onlyOwner {
require(msg.sender == owner, "Error! You're not the smart contract owner!");
_;
}
// Create campaigns
function createCampaing(uint _budgetCampaign) public onlyOwner {
Campaign storage _firstCampaigns = campaigns.push();
_firstCampaigns.campaignID = totalCampaign;
_firstCampaigns.budget = _budgetCampaign;
totalCampaign++;
}
// Bid
function bid(uint _indexCampaign, string memory _nameBidder) public {
Campaign storage _bidCampaign = campaigns[_indexCampaign];
_bidCampaign.bidCount += 1;
uint _bidIndex = _bidCampaign.bidCount;
_bidCampaign.bidders[_indexCampaign].push(Bidder(true, _bidIndex, _nameBidder, msg.sender));
}
// Getter Bids
function getBids(uint _indexCampaign) onlyOwner external view returns(Bidder[] memory) {
return campaigns[_indexCampaign].bidders[_indexCampaign];
}
}
With getBids() function, you retrieve all bids for a specific campaign that it identify with its index. I put a onlyOwner modifier that it allows to specific function that they'll call only from the smart contract owner (rather who deployed for first time smart contract into blockchain).