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 {

    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

  • Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.
    – Community Bot
    May 25, 2022 at 13:03

1 Answer 1


Example of struct array within a struct...

There can be multiple ActionData structs in an Operation (like you might have bidders in a campaign)

interface IWallet {
    struct Operation {
        uint256 nonce;
        IWallet.ActionData[] actions;

    struct ActionData {
        uint256 ethValue;
        address contractAddress;
        bytes encodedFunction;


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