Error with safeTransferFrom erc721

Question

I have moved forward with the contract of a marketplace in a modularised way, that is, I define a contract for the marketplace itself and another one for the auction. In the main contract I extend ERC721BurnableUpgradeable and in the Auction contract I extend ERC721HolderUpgradeable. To the ERC721HolderUpgradeable contract I pass in its migration the address of the main contract (which has an IERC721Upgradeable interface).

Everything went smoothly, mint, auction creation, 1-2-x placeBid... Now when I want to make the claim from the admin account I have this error that I don't understand why I get when I execute the safeTransferFrom method...

tokenContract.safeTransferFrom(msg.sender, _auction_bidder[tokenContract][tokenId], tokenId);

reason: 'ERC721: transfer caller is not owner nor approved'...

Any suggestions?

thanks

Answer 1

It seems like you are not adding an approval for the transfer.

There are two ways to transfer tokens:

1. Direct transfer with transfer function. You own the tokens and you send them to an arbitrary recipient

2. An indirect transfer. You give address X allowance (approve function) to withdraw some amount of your tokens. Typically, in a second transaction, you tell the other contract (X) to do whatever it needed the tokens for - for example a trade. So X then withdraws the tokens from you (with transferFrom) using the allowance you gave it earlier.