Using openZepplin, how do I use the safeTransferFrom(from, to, tokenId, "")?

Solidity Programming
#1

Kindly bare with me as I am new to Solidity and the Web.30 space.

The intention of my DApp is to be able to delay/schedule the transfers of your NFT’s from ones own account to someone else’s.

The idea is that a user should be able to find most of his NFT details via the opensea platform and their MetaMask wallet…

Find below my simple solidity code in the Remix IDE:

// SPDX-License-Identifier: MIT
pragma solidity ^0.6.2;

import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v3.4.0/contracts/token/ERC721/ERC721.sol";

contract CryptoGift is ERC721 {
    address public owner;
    uint256 private birtday = block.timestamp +30; 

     constructor()  ERC721("Crypto Gift", "CGT") public {
        owner = msg.sender;       
    }

    function GiftAFriend (address from, address to, uint256 tokenId) public virtual {

       require( block.timestamp >= birtday, "Its NOT your birthday yet!" );
       safeTransferFrom(from, to, tokenId, ""); 
    }

}

The settings I used in my Remix IDE are:

ENVIRONMENT: Web3 Provider

I was able to successfully Deploy to the Rinkeby Test Network this means I am also able to see all the interfaces in Remix as illustrated below

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When running my GiftAFriend function, I used the details found in my NFT contract/address from my https://testnets.opensea.io/assets/0x1a2795bbdbc6b6fc1d777b47b9c1516a642ca7f7/1 and for the to, I used one of my fictitious MetaMask addresses.

For the tokenId, I used the tokenId at the end of my opensea address https://testnets.opensea.io/assets/0x1a2795bbdbc6b6fc1d777b47b9c1516a642ca7f7/1

When I click the transact for my GiftAFriend function I am met with the following error message in Remix:

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Kindly tell me where/ why am going wrong?

#2

Not so sure, did you try and see what error did you get from etherscan? could be from that require line but I can’t be so sure since I don’t know when did you call GiftAFriend

#3

Hi YosephKS!

I really appreciate the help.

Nothing gets sent to Etherscan at all, so am not able to show you any errors from etherscan, however, what I should have thought of adding to this post, are the error messages I get from the Remix console.

To answer your question, when I call the GiftAFriend function… and I ignore the
Gas estimation failed message as seen in the image below, by clicking on the Send Transaction anyway.

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Below are the error messages I get in the Remix console:

transact to CryptoGift.GiftAFriend pending …
transact to CryptoGift.GiftAFriend errored: Returned error: VM Exception while processing transaction: revert ERC721: operator query for nonexistent token

But as you can see from the screenshot taken from my testnets.opensea.io account: https://testnets.opensea.io/assets/0x1a2795bbdbc6b6fc1d777b47b9c1516a642ca7f7/1

the tokenId for the NFT I am trying to transfer is actually number: 1

1

Where am I going wrong?

#4

hmmm I see, did you by any chance approve the transfer yet for this contract to take the NFT from your wallet? coz I see safeTransferFrom

#5

No I haven’t gotten them approved, how do I get them approved?

#6

you need to call the approve function in the NFT here https://docs.openzeppelin.com/contracts/2.x/api/token/erc721#ERC721-approve-address-uint256-

it needs the to and tokenId to approve

#7

Thanks for the prompt response.

I updated my code to this:

function GiftAFriend (address _from, address _to, uint256 _tokenId) public virtual {
    approve( _to, _tokenId);
    safeTransferFrom(_from, _to, _tokenId, ""); 
}

But getting this error message in the Remix console:

transact to CryptoGift.GiftAFriend pending …
transact to CryptoGift.GiftAFriend errored: Returned error: VM Exception while processing transaction: revert ERC721: owner query for nonexistent token

Could the issue be that I am filling in the fields with the wrong values?
1

Kindly observe that in the from field, I use the NFT address found in the testnets.opensea.io which here is: 0x1a2795bbdbc6b6fc1d777b47b9c1516a642ca7f7

In the to field, I use one of the many addresses provided by the Remix
1

and for the tokenId off course I use the tokenId 1 found in testnets.opensea.io account
1

Am I getting the values to fill in the GiftAFriend correctly?

How do I deliberately add a delay in my Token, ETH and NFT transfer?
#8

Hey sorry for the late reply, but the approve shouldn’t be called in the smart contract, instead you should call it directly from the wallet :raised_hands:

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