Solidity

In this example, we assume that you are building a smart contract where users can submit some sustainable action that is being approved/rejected by some moderator. If the action is approved the user can claim his rewards. No backend is involved.

Your contract should look like this:

// SPDX-License-Identifier: MIT
pragma solidity 0.8.20;

// can find here: https://github.com/vechain/vebetterdao-contracts/tree/main/contracts/interfaces
import "./interfaces/IX2EarnRewardsPool.sol";

/**
 * Example contract with key functionality to interact with the x2Earn rewards pool
 * and distribute rewards.
 * You can customize this contract in the way 
 */
contract MySustainableAppContract {
    IX2EarnRewardsPool public x2EarnRewardsPool;
    bytes32 public VBD_APP_ID;
    
    // a dummy mapping pretending you have a way to track and 
    // validate user actions on chain.
    mapping(uint256 actionId => ActionStruct) public sustainableActions;
    mapping(uint256 actionId => bool) public rewardsClaimed;
    
    // You will need to setup the address of the X2EarnRewardsPool contract
    // and your APP_ID on VeBetterDAO
    constructor(IX2EarnRewardsPool _x2EarnRewardsPool, bytes32 _VBD_APP_ID) {
        x2EarnRewardsPool = _x2EarnRewardsPool;
        VBD_APP_ID = _VBD_APP_ID;
    }

    /**
     * @notice A function that allows a user to claim a reward for a specific
     * sustainable action that they performed.
     * 
     * IMPORTANT: the address of this contract must be set as a distributor 
     * of your APP in order to move funds from the X2EarnRewardsPool contract. 
     * You can set this on the VeBetterDAO governance app.
     */
    function claimReward(uint256 _actionId) external {
        // ... some code to check if the action is valid and user can claim

        // If distributeReward fails, it will revert
        x2EarnRewardsPool.distributeReward(
            VBD_APP_ID,
            actions[_actionId].rewardAmount,
            msg.sender, // this is the user calling the claimReward function
            "" // proof and impacts not provided
        );

        rewardClaimed[_actionId] = true;

        emit RewardClaimed(_actionId, msg.sender);
    }
}

The address of this contract must be set as a distributor of your APP in order to move funds from the X2EarnRewardsPool contract.

You can set this on the VeBetterDAO governance app.

Sustainability Proof

Read more about the proof standard and how we expect you to provide it in the Sustainability Proofs and Impacts section.