Openzeppelin-contracts: Implement DefaultERC721TokenURI and DefaultTokenURI contracts

[shrugs]

🎉 Description

Here's my attempt for ERC721, but perhaps could be improved.

pragma solidity ^0.4.24;
 import "./ERC721Token.sol";

 contract DefaultERC721TokenURI is ERC721Token {
  string private tokenURI_ = "";

   constructor(string _tokenURI)
    public
  {
    require(bytes(_tokenURI).length > 0);
    tokenURI_ = _tokenURI;
  }
   /**
   * @dev Returns a default URI for every tokenId unless a specific URI is set
   * @param _tokenId uint256 ID of the token to query
   */
  function tokenURI(uint256 _tokenId)
    public
    view
    returns (string)
  {
    if (bytes(tokenURIs[_tokenId]).length != 0) {
      return super.tokenURI(_tokenId);
    }
     return tokenURI_;
  }
}

• [x] 📈 This is a feature request.

[logeekal]

I can take it up @shrugs. Your implementation helps and will get back on this.

[frangio]

Hey @logeekal, there's actually been a new related proposal that I prefer: https://github.com/OpenZeppelin/openzeppelin-solidity/issues/1745.

The idea is to generate an automatic URI for each token that is the concatenation of a base URI and the token id. I feel like this provides a more complete solution to the problem.

There is no one working on that at the moment. Would you like to? There is already a library to convert numbers to strings that we built for this purpose in https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1746.

[logeekal]

Thanks @frangio for pitching in and pointed me in right direction. I am here to learn and can certainly take it up. I may need a little help on the way though.

thanks again.

[frangio]

Cool! Closing in favor of #1745 then.