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Pay delegate

Before implementing, learn about delegates here.


A contract can become a treasury pay delegate by adhering to IJBPayDelegate:

interface IJBPayDelegate {
function didPay(JBDidPayData calldata _data) external;

When extending pay functionality with a delegate, the protocol will pass a JBDidPayData to the didPay(...) function:

struct JBDidPayData {
address payer;
uint256 projectId;
uint256 currentFundingCycleConfiguration;
JBTokenAmount amount;
uint256 projectTokenCount;
address beneficiary;
bool preferClaimedTokens;
string memo;
bytes metadata;
struct JBTokenAmount {
address token;
uint256 value;
uint256 decimals;
uint256 currency;

The msg.sender to the delegate will be the payment terminal that facilitated the payment.

In payment terminals based on the JBPayoutRedemptionPaymentTerminal, such as JBETHPaymentTerminal's and JBERC20PaymentTerminal's, the pay delegate hook gets called after the project's tokens have been minted and distributed. View the docs.

Make sure to only allow trusted contracts to access the didPay(...) transaction.


New delegate contracts should be deployed independently. Once deployed, its address can be returned from a data source hook. See how to build a data source for more.


import '@openzeppelin/contracts/token/ERC721/ERC721.sol';
import '@jbx-protocol/contracts-v2/contracts/interfaces/IJBFundingCycleDataSource.sol';
import '@jbx-protocol/contracts-v2/contracts/interfaces/IJBPayDelegate.sol';
import '@jbx-protocol/contracts-v2/contracts/structs/JBTokenAmount.sol';

contract NFTPayDelegate is ERC721, IJBFundingCycleDataSource, IJBPayDelegate {

IJBDirectory directory;
uint256 projectId;
JBTokenAmount contributionThreshold;
uint256 supply;

// This contract can be used as a funding cycle data source to ensure its didPay function is called once the payment has gone through.
function payParams(JBPayParamsData calldata _data)
returns (
uint256 weight,
string memory memo,
IJBPayDelegate delegate
// Forward the recieved weight and memo, and use this contract as a pay delegate.
return (_data.weight, _data.memo, IJBPayDelegate(address(this)));

// This is unused but needs to be included to fulfill IJBFundingCycleDataSource.
function redeemParams(JBRedeemParamsData calldata _data)
returns (
uint256 reclaimAmount,
string memory memo,
IJBRedemptionDelegate delegate
// Return the default values.
return (_data.reclaimAmount.value, _data.memo, IJBRedemptionDelegate(address(0)));

constructor(IJBDirectory _directory, uint256 _projectId, JBTokenAmount _contributionThreshold, string calldata _name, string calldata _symbol) ERC721(_name, _symbol) {
directory = _directory;
projectId = _projectId;

// Called once the payment has gone through if the project's current funding cycle is using a data source that returns this delegate.
function didPay(JBDidPayData calldata _data) external override {
// Make sure the caller is a terminal of the project, and the call is being made on behalf of an interaction with the correct project.
if (
!directory.isTerminalOf(projectId, IJBPaymentTerminal(msg.sender)) ||
_data.projectId != projectId

// Make the contribution is being made in the expected token.
if (_data.amount.token != contributionThreshold.token) return;

// Make sure the values use the same number of decimals.
if (_data.amount.decimals < contributionThreshold.decimals) return;

// Make sure the threshold is met.
if (_data.amount.value < contributionThreshold.value) return;

uint256 _tokenId = ++supply;

_mint(_data.beneficiary, _tokenId);