How to send ETH to smart contract? - solidity

Question

I want an address to send ETH to the smart contract in the RSVP function.
pragma solidity ^0.8.0;
import "hardhat/console.sol";
contract MeetingCreation {
struct Meeting {
address meeting_creator;
uint256 meetingID;
string name;
string description;
uint256 start_date;
uint256 end_date;
uint256 max_tickets;
uint256 ticket_price;
uint256 current_tickets_sold;
address[] attendees;
}
function sendETHtoContract(uint256 j) public payable {
}
function RSVP (uint256 MEETINGID) public payable {
//get the Meeting ID
Meeting storage m = meetings[MEETINGID];
require(m.current_tickets_sold < m.max_tickets,
"No more tickets available"
);
require(msg.sender.balance >= m.ticket_price,
"Not enough funds"
);
console.log("funds before paying", msg.sender.balance);
console.log("funds in smart contract before paying", address(this).balance);
//Attempt #1 To send ETH to contract
sendETHtoContract(m.ticket_price);
//Attempt #2 To send ETH to contract
(bool success, ) = address(this).call{value: m.ticket_price}("");
//Attempt #3 to send ETH to contract
payable(address(this).transfer(msg.value));
console.log("funds AFTEr paying", msg.sender.balance);
console.log("funds in smart contract AFTER paying", address(this).balance);
address[] storage adr;
adr = m.attendees;
adr.push(msg.sender);
m.current_tickets_sold += 1;
}
Both sendETHtoContract and (bool, success) result in not sending any ETH when I tried 3 different addresses.
funds before paying 9999949127225257315696
funds in smart contract before paying 0
funds AFTEr paying 9999949127225257315696
funds in smart contract AFTER paying 0
funds before paying 9999955000801324655336
funds in smart contract before paying 0
funds AFTEr paying 9999955000801324655336
funds in smart contract AFTER paying 0
When I tried using the transfer function, this is the error I get when the contract tries to compile:
"send" and "transfer" are only available for objects of type "address payable", not "address".

Answer 1

I assume that you can delete your attempt for the simple reason that when you add payable modifier, it handle the transfer about ETH from address to smart contract and viceversa.
Said this, I think that you're not enhancing msg.value field. If you using remix IDE, before call RSVP function go into DEPLOY & RUN TRANSACTIONS section and put into VALUE textbox a value that you want sending to smart contract and then you can call RSVP function.
I adjust your smart contract delete your attempts. Try it:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "hardhat/console.sol";
contract MeetingCreation {
struct Meeting {
address meeting_creator;
uint256 meetingID;
string name;
string description;
uint256 start_date;
uint256 end_date;
uint256 max_tickets;
uint256 ticket_price;
uint256 current_tickets_sold;
address[] attendees;
}
mapping(uint => Meeting) meetings;
function RSVP (uint256 MEETINGID) public payable {
//get the Meeting ID
Meeting storage m = meetings[MEETINGID];
require(m.current_tickets_sold < m.max_tickets,
"No more tickets available"
);
require(msg.sender.balance >= m.ticket_price,
"Not enough funds"
);
address[] storage adr;
adr = m.attendees;
adr.push(msg.sender);
m.current_tickets_sold += 1;
}
// NOTE: Get smart contract balance
function getSmartContractBalance() external view returns(uint) {
return address(this).balance;
}
}