[Ethereum] safeTransferFrom is undefined in buidler test

address.transfererc-721openzeppelinopenzeppelin-contractssolidity

I have started using buidler for testing/compiling my contracts. In one test i have setup a scenario that a owner attempts to transfer a token to another wallet address.

My contract is inheriting from the Open Zeppelin ERC721.sol one. When trying to call token.safeTransferFrom(args) it says that safeTransferFrom is not a a function and when logging it out it shows as undefined.

Im pretty new to solidity and smart contract coding but looking through the source I can see that the function declaration looks the same as approve which I can call quite happily using token.approve(args).

Is there anything obvious that Im missing?

Best Answer

Ran into this myself as well. Are you using ethers.js with Buidler?

The safeTransferFrom method is overloaded and generally with ethers.js the bare definition is the default method used.

If you run console.log( Object.keys(token) ) you'll see the methods on the token and you'll likely see two definitions of safeTransferFrom. Pick the one you want to use then you can call it like this:

token['safeTransferFrom(address,address,uint256)'](fromAddr, toAddr, tokenId);

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import "github.com/OpenZeppelin/openzeppelin-solidity/contracts/token/ERC721/IERC721.sol";
import "github.com/OpenZeppelin/openzeppelin-solidity/contracts/token/ERC721/IERC721Receiver.sol";
import "github.com/OpenZeppelin/openzeppelin-solidity/contracts/math/SafeMath.sol";
import "github.com/OpenZeppelin/openzeppelin-solidity/contracts/utils/Address.sol";
import "github.com/OpenZeppelin/openzeppelin-solidity/contracts/drafts/Counters.sol";
import "github.com/OpenZeppelin/openzeppelin-solidity/contracts/introspection/ERC165.sol";

This compiles. I am not sure about the v2.0.0 on counter. I replaced that with master.

Solidity and ERC-721 – What is the Bytes Data Param in safeTransferFrom?

Considering you are interfacing with an existing contract (i.e. calling it).

You can send any data you want, such as a string converted to bytes. Here is just one example I have lying around on how to wrangle strings and bytes https://github.com/su-squares/ethereum-contract/blob/master/contracts/SuNFT.sol#L221-L239

The reason why you would do this is application-specific. In other words, only send data if the specific ERC-721 contract you are sending to tells you to, and follow any prescriptions they give you. The myriad ways that applications could describe how you would use these bytes could not be predicted in 2018 (when ERC-721 finalized) and no value existed in cataloging and standardizing these use cases ahead of time.

Best Answer

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