币安链BSC上NFT发行教程——NFT合约中的代理人针对所有NFT的授权功能【pdf+视频BSC链NFT发行教程下载】

在NFT合约中提供了区别于ERC20的代理人授权功能，可以将自己钱包地址下的所有nft的所有权一次性授权给代理人，不用针对每个nft做单独的授权操作。该功能适用于针对NFT的统一授权，被授权者具备了授权者钱包地址下所有nft的所有权限，可以执行nft的transfer，burn等功能。代理人授权功能代码片段如下：

/**
     * @dev Sets or unsets the approval of a given operator
     * An operator is allowed to transfer all tokens of the sender on their behalf.
     * @param to operator address to set the approval
     * @param approved representing the status of the approval to be set
     */
    function setApprovalForAll(address to, bool approved) public {
        require(to != _msgSender(), "TRC721: approve to caller");

        _operatorApprovals[_msgSender()][to] = approved;
        emit ApprovalForAll(_msgSender(), to, approved);
    }

对应的授权查询接口：

/**
     * @dev Tells whether an operator is approved by a given owner.
     * @param owner owner address which you want to query the approval of
     * @param operator operator address which you want to query the approval of
     * @return bool whether the given operator is approved by the given owner
     */
    function isApprovedForAll(address owner, address operator) public view returns (bool) {
        return _operatorApprovals[owner][operator];
    }

判断是否为全权代理人接口：

/**
     * @dev Returns whether the given spender can transfer a given token ID.
     * @param spender address of the spender to query
     * @param tokenId uint256 ID of the token to be transferred
     * @return bool whether the msg.sender is approved for the given token ID,
     * is an operator of the owner, or is the owner of the token
     */
    function _isApprovedOrOwner(address spender, uint256 tokenId) internal view returns (bool) {
        require(_exists(tokenId), "TRC721: operator query for nonexistent token");
        address owner = ownerOf(tokenId);
        return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
    }

通过接口isApprovedOrOwner判断是否为全权代理人，如果以及获取授权者所有NFT的权限，可以越过所有者执行transfer，burn，mint等相关操作权限。

至此，完成NFT合约中的代理人针对所有NFT的授权功能所有操作流程。

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