How to add minimum and maximum purchase amounts to Allowance Crowdsale

Rahaman · December 9, 2020, 1:37pm

@abcoathup I’m confused how to add minimum and maximum amount like users need to send more then 0.1 ether and maximum 1 ether ! How to add this function on this above AllowanceCrowdsale ??? Please help me on this !

abcoathup · December 10, 2020, 3:27am

Hi @Rahaman,

You can add some validation by overriding _preValidatePurchase. I suggest looking at IndividuallyCappedCrowdsale for the concept.

For a minimum purchase you could check the weiAmount. For a maximum, you could check against a contract set cap, but participants could participate multiple times to get around the cap, so you would ideally add participants to a white list/allow list or use IndividuallyCappedCrowdsale and set a cap per address of those who are allowed to participate, so that one person didn’t participate using multiple addresses.

github.com

OpenZeppelin/openzeppelin-contracts/blob/v2.5.1/contracts/crowdsale/validation/IndividuallyCappedCrowdsale.sol#L49


 */
function getContribution(address beneficiary) public view returns (uint256) {
    return _contributions[beneficiary];
}
/**
 * @dev Extend parent behavior requiring purchase to respect the beneficiary's funding cap.
 * @param beneficiary Token purchaser
 * @param weiAmount Amount of wei contributed
 */
function _preValidatePurchase(address beneficiary, uint256 weiAmount) internal view {
    super._preValidatePurchase(beneficiary, weiAmount);
    // solhint-disable-next-line max-line-length
    require(_contributions[beneficiary].add(weiAmount) <= _caps[beneficiary], "IndividuallyCappedCrowdsale: beneficiary's cap exceeded");
}
/**
 * @dev Extend parent behavior to update beneficiary contributions.
 * @param beneficiary Token purchaser
 * @param weiAmount Amount of wei contributed
 */

Rahaman · December 10, 2020, 7:39am

@abcoathup Thank you sir !

abdul · March 30, 2021, 5:35pm

how can i get in contact with you are you on telegram @Rahaman

Rahaman · March 30, 2021, 5:48pm

Yes @SekhMotibulRahaman

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How to add minimum and maximum purchase amounts to Allowance Crowdsale

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