Oasis-Eth黑客马拉松大赛 --- 挑战2攻略
上回写了Oasis-Eth黑客马拉松大赛 --- 挑战1攻略，这回写挑战2的攻略
第一个挑战是写个ERC-20代币，第二个挑战则是写个ERC-721代币，也就是最近特别火的NFT代币
挑战＃2-创建一个NFT（100 ROSE，1 OETH）
获取钱包地址
进入智能合约开发的Web端网站：https://buidl.secondstate.io/
点击左下角钢笔的图形，复制显示的第一个钱包地址：
通过水龙头网站获得测试币
进入水龙头网站： http://faucet.oasiseth.org/ 输入上一步复制的钱包地址获得0.01 OETH测试币
创建ERC-721代币
如果你知道怎么写ERC-721代币的合约，直接跳过这一步。
如果你不知道怎么写合约，复制下面的代码到智能合约开发的Web端网站，修改一下代币的名字和代号就好了（代码最下面）。比如我的代币的名字是Ericet NFT，代号是ET
pragma solidity >=0.4.0 <0.6.0;
// File: openzeppelin-solidity/contracts/introspection/IERC165.sol
/**
* @title IERC165
* @dev https://github.com/ethereum/EIPs/blob/master/EIPS/eip-165.md
*/
interface IERC165 {
/**
* @notice Query if a contract implements an interface
* @param interfaceId The interface identifier, as specified in ERC-165
* @dev Interface identification is specified in ERC-165. This function
* uses less than 30,000 gas.
*/
function supportsInterface(bytes4 interfaceId)
external
view
returns (bool);
}
// File: openzeppelin-solidity/contracts/token/ERC721/IERC721.sol
/**
* @title ERC721 Non-Fungible Token Standard basic interface
* @dev see https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
*/
contract IERC721 is IERC165 {
event Transfer(
address indexed from,
address indexed to,
uint256 indexed tokenId
);
event Approval(
address indexed owner,
address indexed approved,
uint256 indexed tokenId
);
event ApprovalForAll(
address indexed owner,
address indexed operator,
bool approved
);
function balanceOf(address owner) public view returns (uint256 balance);
function ownerOf(uint256 tokenId) public view returns (address owner);
function approve(address to, uint256 tokenId) public;
function getApproved(uint256 tokenId)
public view returns (address operator);
function setApprovalForAll(address operator, bool _approved) public;
function isApprovedForAll(address owner, address operator)
public view returns (bool);
function transferFrom(address from, address to, uint256 tokenId) public;
function safeTransferFrom(address from, address to, uint256 tokenId)
public;
function safeTransferFrom(
address from,
address to,
uint256 tokenId,
bytes data
)
public;
}
// File: openzeppelin-solidity/contracts/token/ERC721/IERC721Receiver.sol
/**
* @title ERC721 token receiver interface
* @dev Interface for any contract that wants to support safeTransfers
* from ERC721 asset contracts.
*/
contract IERC721Receiver {
/**
* @notice Handle the receipt of an NFT
* @dev The ERC721 smart contract calls this function on the recipient
* after a `safeTransfer`. This function MUST return the function selector,
* otherwise the caller will revert the transaction. The selector to be
* returned can be obtained as `this.onERC721Received.selector`. This
* function MAY throw to revert and reject the transfer.
* Note: the ERC721 contract address is always the message sender.
* @param operator The address which called `safeTransferFrom` function
* @param from The address which previously owned the token
* @param tokenId The NFT identifier which is being transferred
* @param data Additional data with no specified format
* @return `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`
*/
function onERC721Received(
address operator,
address from,
uint256 tokenId,
bytes data
)
public
returns(bytes4);
}
// File: openzeppelin-solidity/contracts/math/SafeMath.sol
/**
* @title SafeMath
* @dev Math operations with safety checks that revert on error
*/
library SafeMath {
/**
* @dev Multiplies two numbers, reverts on overflow.
*/
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
// Gas optimization: this is cheaper than requiring 'a' not being zero, but the
// benefit is lost if 'b' is also tested.
// See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
if (a == 0) {
return 0;
}
uint256 c = a * b;
require(c / a == b);
return c;
}
/**
* @dev Integer division of two numbers truncating the quotient, reverts on division by zero.
*/
function div(uint256 a, uint256 b) internal pure returns (uint256) {
require(b > 0); // Solidity only automatically asserts when dividing by 0
uint256 c = a / b;
// assert(a == b * c + a % b); // There is no case in which this doesn't hold
return c;
}
/**
* @dev Subtracts two numbers, reverts on overflow (i.e. if subtrahend is greater than minuend).
*/
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
require(b <= a);
uint256 c = a - b;
return c;
}
/**
* @dev Adds two numbers, reverts on overflow.
*/
function add(uint256 a, uint256 b) internal pure returns (uint256) {
uint256 c = a + b;
require(c >= a);
return c;
}
/**
* @dev Divides two numbers and returns the remainder (unsigned integer modulo),
* reverts when dividing by zero.
*/
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
require(b != 0);
return a % b;
}
}
// File: openzeppelin-solidity/contracts/utils/Address.sol
/**
* Utility library of inline functions on addresses
*/
library Address {
/**
* Returns whether the target address is a contract
* @dev This function will return false if invoked during the constructor of a contract,
* as the code is not actually created until after the constructor finishes.
* @param account address of the account to check
* @return whether the target address is a contract
*/
function isContract(address account) internal view returns (bool) {
uint256 size;
// XXX Currently there is no better way to check if there is a contract in an address
// than to check the size of the code at that address.
// See https://ethereum.stackexchange.com/a/14016/36603
// for more details about how this works.
// TODO Check this again before the Serenity release, because all addresses will be
// contracts then.
// solium-disable-next-line security/no-inline-assembly
assembly { size := extcodesize(account) }
return size > 0;
}
}
// File: openzeppelin-solidity/contracts/introspection/ERC165.sol
/**
* @title ERC165
* @author Matt Condon (@shrugs)
* @dev Implements ERC165 using a lookup table.
*/
contract ERC165 is IERC165 {
bytes4 private constant _InterfaceId_ERC165 = 0x01ffc9a7;
/**
* 0x01ffc9a7 ===
* bytes4(keccak256('supportsInterface(bytes4)'))
*/
/**
* @dev a mapping of interface id to whether or not it's supported
*/
mapping(bytes4 => bool) private _supportedInterfaces;
/**
* @dev A contract implementing SupportsInterfaceWithLookup
* implement ERC165 itself
*/
constructor()
internal
{
_registerInterface(_InterfaceId_ERC165);
}
/**
* @dev implement supportsInterface(bytes4) using a lookup table
*/
function supportsInterface(bytes4 interfaceId)
external
view
returns (bool)
{
return _supportedInterfaces[interfaceId];
}
/**
* @dev internal method for registering an interface
*/
function _registerInterface(bytes4 interfaceId)
internal
{
require(interfaceId != 0xffffffff);
_supportedInterfaces[interfaceId] = true;
}
}
// File: openzeppelin-solidity/contracts/token/ERC721/ERC721.sol
/**
* @title ERC721 Non-Fungible Token Standard basic implementation
* @dev see https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
*/
contract ERC721 is ERC165, IERC721 {
using SafeMath for uint256;
using Address for address;
// Equals to `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`
// which can be also obtained as `IERC721Receiver(0).onERC721Received.selector`
bytes4 private constant _ERC721_RECEIVED = 0x150b7a02;
// Mapping from token ID to owner
mapping (uint256 => address) private _tokenOwner;
// Mapping from token ID to approved address
mapping (uint256 => address) private _tokenApprovals;
// Mapping from owner to number of owned token
mapping (address => uint256) private _ownedTokensCount;
// Mapping from owner to operator approvals
mapping (address => mapping (address => bool)) private _operatorApprovals;
bytes4 private constant _InterfaceId_ERC721 = 0x80ac58cd;
/*
* 0x80ac58cd ===
* bytes4(keccak256('balanceOf(address)')) ^
* bytes4(keccak256('ownerOf(uint256)')) ^
* bytes4(keccak256('approve(address,uint256)')) ^
* bytes4(keccak256('getApproved(uint256)')) ^
* bytes4(keccak256('setApprovalForAll(address,bool)')) ^
* bytes4(keccak256('isApprovedForAll(address,address)')) ^
* bytes4(keccak256('transferFrom(address,address,uint256)')) ^
* bytes4(keccak256('safeTransferFrom(address,address,uint256)')) ^
* bytes4(keccak256('safeTransferFrom(address,address,uint256,bytes)'))
*/
constructor()
public
{
// register the supported interfaces to conform to ERC721 via ERC165
_registerInterface(_InterfaceId_ERC721);
}
/**
* @dev Gets the balance of the specified address
* @param owner address to query the balance of
* @return uint256 representing the amount owned by the passed address
*/
function balanceOf(address owner) public view returns (uint256) {
require(owner != address(0));
return _ownedTokensCount[owner];
}
/**
* @dev Gets the owner of the specified token ID
* @param tokenId uint256 ID of the token to query the owner of
* @return owner address currently marked as the owner of the given token ID
*/
function ownerOf(uint256 tokenId) public view returns (address) {
address owner = _tokenOwner[tokenId];
require(owner != address(0));
return owner;
}
/**
* @dev Approves another address to transfer the given token ID
* The zero address indicates there is no approved address.
* There can only be one approved address per token at a given time.
* Can only be called by the token owner or an approved operator.
* @param to address to be approved for the given token ID
* @param tokenId uint256 ID of the token to be approved
*/
function approve(address to, uint256 tokenId) public {
address owner = ownerOf(tokenId);
require(to != owner);
require(msg.sender == owner || isApprovedForAll(owner, msg.sender));
_tokenApprovals[tokenId] = to;
emit Approval(owner, to, tokenId);
}
/**
* @dev Gets the approved address for a token ID, or zero if no address set
* Reverts if the token ID does not exist.
* @param tokenId uint256 ID of the token to query the approval of
* @return address currently approved for the given token ID
*/
function getApproved(uint256 tokenId) public view returns (address) {
require(_exists(tokenId));
return _tokenApprovals[tokenId];
}
/**
* @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 != msg.sender);
_operatorApprovals[msg.sender][to] = approved;
emit ApprovalForAll(msg.sender, to, approved);
}
/**
* @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];
}
/**
* @dev Transfers the ownership of a given token ID to another address
* Usage of this method is discouraged, use `safeTransferFrom` whenever possible
* Requires the msg sender to be the owner, approved, or operator
* @param from current owner of the token
* @param to address to receive the ownership of the given token ID
* @param tokenId uint256 ID of the token to be transferred
*/
function transferFrom(
address from,
address to,
uint256 tokenId
)
public
{
require(_isApprovedOrOwner(msg.sender, tokenId));
require(to != address(0));
_clearApproval(from, tokenId);
_removeTokenFrom(from, tokenId);
_addTokenTo(to, tokenId);
emit Transfer(from, to, tokenId);
}
/**
* @dev Safely transfers the ownership of a given token ID to another address
* If the target address is a contract, it must implement `onERC721Received`,
* which is called upon a safe transfer, and return the magic value
* `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
* the transfer is reverted.
*
* Requires the msg sender to be the owner, approved, or operator
* @param from current owner of the token
* @param to address to receive the ownership of the given token ID
* @param tokenId uint256 ID of the token to be transferred
*/
function safeTransferFrom(
address from,
address to,
uint256 tokenId
)
public
{
// solium-disable-next-line arg-overflow
safeTransferFrom(from, to, tokenId, "");
}
/**
* @dev Safely transfers the ownership of a given token ID to another address
* If the target address is a contract, it must implement `onERC721Received`,
* which is called upon a safe transfer, and return the magic value
* `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
* the transfer is reverted.
* Requires the msg sender to be the owner, approved, or operator
* @param from current owner of the token
* @param to address to receive the ownership of the given token ID
* @param tokenId uint256 ID of the token to be transferred
* @param _data bytes data to send along with a safe transfer check
*/
function safeTransferFrom(
address from,
address to,
uint256 tokenId,
bytes _data
)
public
{
transferFrom(from, to, tokenId);
// solium-disable-next-line arg-overflow
require(_checkOnERC721Received(from, to, tokenId, _data));
}
/**
* @dev Returns whether the specified token exists
* @param tokenId uint256 ID of the token to query the existence of
* @return whether the token exists
*/
function _exists(uint256 tokenId) internal view returns (bool) {
address owner = _tokenOwner[tokenId];
return owner != address(0);
}
/**
* @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)
{
address owner = ownerOf(tokenId);
// Disable solium check because of
// https://github.com/duaraghav8/Solium/issues/175
// solium-disable-next-line operator-whitespace
return (
spender == owner ||
getApproved(tokenId) == spender ||
isApprovedForAll(owner, spender)
);
}
/**
* @dev Internal function to mint a new token
* Reverts if the given token ID already exists
* @param to The address that will own the minted token
* @param tokenId uint256 ID of the token to be minted by the msg.sender
*/
function _mint(address to, uint256 tokenId) internal {
require(to != address(0));
_addTokenTo(to, tokenId);
emit Transfer(address(0), to, tokenId);
}
/**
* @dev Internal function to burn a specific token
* Reverts if the token does not exist
* @param tokenId uint256 ID of the token being burned by the msg.sender
*/
function _burn(address owner, uint256 tokenId) internal {
_clearApproval(owner, tokenId);
_removeTokenFrom(owner, tokenId);
emit Transfer(owner, address(0), tokenId);
}
/**
* @dev Internal function to add a token ID to the list of a given address
* Note that this function is left internal to make ERC721Enumerable possible, but is not
* intended to be called by custom derived contracts: in particular, it emits no Transfer event.
* @param to address representing the new owner of the given token ID
* @param tokenId uint256 ID of the token to be added to the tokens list of the given address
*/
function _addTokenTo(address to, uint256 tokenId) internal {
require(_tokenOwner[tokenId] == address(0));
_tokenOwner[tokenId] = to;
_ownedTokensCount[to] = _ownedTokensCount[to].add(1);
}
/**
* @dev Internal function to remove a token ID from the list of a given address
* Note that this function is left internal to make ERC721Enumerable possible, but is not
* intended to be called by custom derived contracts: in particular, it emits no Transfer event,
* and doesn't clear approvals.
* @param from address representing the previous owner of the given token ID
* @param tokenId uint256 ID of the token to be removed from the tokens list of the given address
*/
function _removeTokenFrom(address from, uint256 tokenId) internal {
require(ownerOf(tokenId) == from);
_ownedTokensCount[from] = _ownedTokensCount[from].sub(1);
_tokenOwner[tokenId] = address(0);
}
/**
* @dev Internal function to invoke `onERC721Received` on a target address
* The call is not executed if the target address is not a contract
* @param from address representing the previous owner of the given token ID
* @param to target address that will receive the tokens
* @param tokenId uint256 ID of the token to be transferred
* @param _data bytes optional data to send along with the call
* @return whether the call correctly returned the expected magic value
*/
function _checkOnERC721Received(
address from,
address to,
uint256 tokenId,
bytes _data
)
internal
returns (bool)
{
if (!to.isContract()) {
return true;
}
bytes4 retval = IERC721Receiver(to).onERC721Received(
msg.sender, from, tokenId, _data);
return (retval == _ERC721_RECEIVED);
}
/**
* @dev Private function to clear current approval of a given token ID
* Reverts if the given address is not indeed the owner of the token
* @param owner owner of the token
* @param tokenId uint256 ID of the token to be transferred
*/
function _clearApproval(address owner, uint256 tokenId) private {
require(ownerOf(tokenId) == owner);
if (_tokenApprovals[tokenId] != address(0)) {
_tokenApprovals[tokenId] = address(0);
}
}
}
// File: openzeppelin-solidity/contracts/token/ERC721/IERC721Enumerable.sol
/**
* @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
* @dev See https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
*/
contract IERC721Enumerable is IERC721 {
function totalSupply() public view returns (uint256);
function tokenOfOwnerByIndex(
address owner,
uint256 index
)
public
view
returns (uint256 tokenId);
function tokenByIndex(uint256 index) public view returns (uint256);
}
// File: openzeppelin-solidity/contracts/token/ERC721/ERC721Enumerable.sol
contract ERC721Enumerable is ERC165, ERC721, IERC721Enumerable {
// Mapping from owner to list of owned token IDs
mapping(address => uint256[]) private _ownedTokens;
// Mapping from token ID to index of the owner tokens list
mapping(uint256 => uint256) private _ownedTokensIndex;
// Array with all token ids, used for enumeration
uint256[] private _allTokens;
// Mapping from token id to position in the allTokens array
mapping(uint256 => uint256) private _allTokensIndex;
bytes4 private constant _InterfaceId_ERC721Enumerable = 0x780e9d63;
/**
* 0x780e9d63 ===
* bytes4(keccak256('totalSupply()')) ^
* bytes4(keccak256('tokenOfOwnerByIndex(address,uint256)')) ^
* bytes4(keccak256('tokenByIndex(uint256)'))
*/
/**
* @dev Constructor function
*/
constructor() public {
// register the supported interface to conform to ERC721 via ERC165
_registerInterface(_InterfaceId_ERC721Enumerable);
}
/**
* @dev Gets the token ID at a given index of the tokens list of the requested owner
* @param owner address owning the tokens list to be accessed
* @param index uint256 representing the index to be accessed of the requested tokens list
* @return uint256 token ID at the given index of the tokens list owned by the requested address
*/
function tokenOfOwnerByIndex(
address owner,
uint256 index
)
public
view
returns (uint256)
{
require(index < balanceOf(owner));
return _ownedTokens[owner][index];
}
/**
* @dev Gets the total amount of tokens stored by the contract
* @return uint256 representing the total amount of tokens
*/
function totalSupply() public view returns (uint256) {
return _allTokens.length;
}
/**
* @dev Gets the token ID at a given index of all the tokens in this contract
* Reverts if the index is greater or equal to the total number of tokens
* @param index uint256 representing the index to be accessed of the tokens list
* @return uint256 token ID at the given index of the tokens list
*/
function tokenByIndex(uint256 index) public view returns (uint256) {
require(index < totalSupply());
return _allTokens[index];
}
/**
* @dev Internal function to add a token ID to the list of a given address
* This function is internal due to language limitations, see the note in ERC721.sol.
* It is not intended to be called by custom derived contracts: in particular, it emits no Transfer event.
* @param to address representing the new owner of the given token ID
* @param tokenId uint256 ID of the token to be added to the tokens list of the given address
*/
function _addTokenTo(address to, uint256 tokenId) internal {
super._addTokenTo(to, tokenId);
uint256 length = _ownedTokens[to].length;
_ownedTokens[to].push(tokenId);
_ownedTokensIndex[tokenId] = length;
}
/**
* @dev Internal function to remove a token ID from the list of a given address
* This function is internal due to language limitations, see the note in ERC721.sol.
* It is not intended to be called by custom derived contracts: in particular, it emits no Transfer event,
* and doesn't clear approvals.
* @param from address representing the previous owner of the given token ID
* @param tokenId uint256 ID of the token to be removed from the tokens list of the given address
*/
function _removeTokenFrom(address from, uint256 tokenId) internal {
super._removeTokenFrom(from, tokenId);
// To prevent a gap in the array, we store the last token in the index of the token to delete, and
// then delete the last slot.
uint256 tokenIndex = _ownedTokensIndex[tokenId];
uint256 lastTokenIndex = _ownedTokens[from].length.sub(1);
uint256 lastToken = _ownedTokens[from][lastTokenIndex];
_ownedTokens[from][tokenIndex] = lastToken;
// This also deletes the contents at the last position of the array
_ownedTokens[from].length--;
// Note that this will handle single-element arrays. In that case, both tokenIndex and lastTokenIndex are going to
// be zero. Then we can make sure that we will remove tokenId from the ownedTokens list since we are first swapping
// the lastToken to the first position, and then dropping the element placed in the last position of the list
_ownedTokensIndex[tokenId] = 0;
_ownedTokensIndex[lastToken] = tokenIndex;
}
/**
* @dev Internal function to mint a new token
* Reverts if the given token ID already exists
* @param to address the beneficiary that will own the minted token
* @param tokenId uint256 ID of the token to be minted by the msg.sender
*/
function _mint(address to, uint256 tokenId) internal {
super._mint(to, tokenId);
_allTokensIndex[tokenId] = _allTokens.length;
_allTokens.push(tokenId);
}
/**
* @dev Internal function to burn a specific token
* Reverts if the token does not exist
* @param owner owner of the token to burn
* @param tokenId uint256 ID of the token being burned by the msg.sender
*/
function _burn(address owner, uint256 tokenId) internal {
super._burn(owner, tokenId);
// Reorg all tokens array
uint256 tokenIndex = _allTokensIndex[tokenId];
uint256 lastTokenIndex = _allTokens.length.sub(1);
uint256 lastToken = _allTokens[lastTokenIndex];
_allTokens[tokenIndex] = lastToken;
_allTokens[lastTokenIndex] = 0;
_allTokens.length--;
_allTokensIndex[tokenId] = 0;
_allTokensIndex[lastToken] = tokenIndex;
}
}
// File: openzeppelin-solidity/contracts/token/ERC721/IERC721Metadata.sol
/**
* @title ERC-721 Non-Fungible Token Standard, optional metadata extension
* @dev See https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
*/
contract IERC721Metadata is IERC721 {
function name() external view returns (string);
function symbol() external view returns (string);
function tokenURI(uint256 tokenId) external view returns (string);
}
// File: openzeppelin-solidity/contracts/token/ERC721/ERC721Metadata.sol
contract ERC721Metadata is ERC165, ERC721, IERC721Metadata {
// Token name
string private _name;
// Token symbol
string private _symbol;
// Optional mapping for token URIs
mapping(uint256 => string) private _tokenURIs;
bytes4 private constant InterfaceId_ERC721Metadata = 0x5b5e139f;
/**
* 0x5b5e139f ===
* bytes4(keccak256('name()')) ^
* bytes4(keccak256('symbol()')) ^
* bytes4(keccak256('tokenURI(uint256)'))
*/
/**
* @dev Constructor function
*/
constructor(string name, string symbol) public {
_name = name;
_symbol = symbol;
// register the supported interfaces to conform to ERC721 via ERC165
_registerInterface(InterfaceId_ERC721Metadata);
}
/**
* @dev Gets the token name
* @return string representing the token name
*/
function name() external view returns (string) {
return _name;
}
/**
* @dev Gets the token symbol
* @return string representing the token symbol
*/
function symbol() external view returns (string) {
return _symbol;
}
/**
* @dev Returns an URI for a given token ID
* Throws if the token ID does not exist. May return an empty string.
* @param tokenId uint256 ID of the token to query
*/
function tokenURI(uint256 tokenId) external view returns (string) {
require(_exists(tokenId));
return _tokenURIs[tokenId];
}
/**
* @dev Internal function to set the token URI for a given token
* Reverts if the token ID does not exist
* @param tokenId uint256 ID of the token to set its URI
* @param uri string URI to assign
*/
function _setTokenURI(uint256 tokenId, string uri) internal {
require(_exists(tokenId));
_tokenURIs[tokenId] = uri;
}
/**
* @dev Internal function to burn a specific token
* Reverts if the token does not exist
* @param owner owner of the token to burn
* @param tokenId uint256 ID of the token being burned by the msg.sender
*/
function _burn(address owner, uint256 tokenId) internal {
super._burn(owner, tokenId);
// Clear metadata (if any)
if (bytes(_tokenURIs[tokenId]).length != 0) {
delete _tokenURIs[tokenId];
}
}
}
// File: openzeppelin-solidity/contracts/token/ERC721/ERC721Full.sol
/**
* @title Full ERC721 Token
* This implementation includes all the required and some optional functionality of the ERC721 standard
* Moreover, it includes approve all functionality using operator terminology
* @dev see https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
*/
contract ERC721Full is ERC721, ERC721Enumerable, ERC721Metadata {
constructor(string name, string symbol) ERC721Metadata(name, symbol)
public
{
}
}
// File: openzeppelin-solidity/contracts/access/Roles.sol
/**
* @title Roles
* @dev Library for managing addresses assigned to a Role.
*/
library Roles {
struct Role {
mapping (address => bool) bearer;
}
/**
* @dev give an account access to this role
*/
function add(Role storage role, address account) internal {
require(account != address(0));
require(!has(role, account));
role.bearer[account] = true;
}
/**
* @dev remove an account's access to this role
*/
function remove(Role storage role, address account) internal {
require(account != address(0));
require(has(role, account));
role.bearer[account] = false;
}
/**
* @dev check if an account has this role
* @return bool
*/
function has(Role storage role, address account)
internal
view
returns (bool)
{
require(account != address(0));
return role.bearer[account];
}
}
// File: openzeppelin-solidity/contracts/access/roles/MinterRole.sol
contract MinterRole {
using Roles for Roles.Role;
event MinterAdded(address indexed account);
event MinterRemoved(address indexed account);
Roles.Role private minters;
constructor() internal {
_addMinter(msg.sender);
}
modifier onlyMinter() {
require(isMinter(msg.sender));
_;
}
function isMinter(address account) public view returns (bool) {
return minters.has(account);
}
function addMinter(address account) public onlyMinter {
_addMinter(account);
}
function renounceMinter() public {
_removeMinter(msg.sender);
}
function _addMinter(address account) internal {
minters.add(account);
emit MinterAdded(account);
}
function _removeMinter(address account) internal {
minters.remove(account);
emit MinterRemoved(account);
}
}
// File: openzeppelin-solidity/contracts/token/ERC721/ERC721Mintable.sol
/**
* @title ERC721Mintable
* @dev ERC721 minting logic
*/
contract ERC721Mintable is ERC721, MinterRole {
/**
* @dev Function to mint tokens
* @param to The address that will receive the minted tokens.
* @param tokenId The token id to mint.
* @return A boolean that indicates if the operation was successful.
*/
function mint(
address to,
uint256 tokenId
)
public
onlyMinter
returns (bool)
{
_mint(to, tokenId);
return true;
}
}
// File: contracts/PaintingMasterpiece.sol
contract MyNFT is ERC721Full, ERC721Mintable {
constructor() ERC721Full("NFT名字", "NFT代号") public {
}
function mintToken(address to, uint256 tokenId, string uri) public {
mint(to, tokenId);
require(_exists(tokenId));
_setTokenURI(tokenId, uri);
}
function burnToken(address owner, uint256 tokenId) public {
_burn(owner, tokenId);
}
}
部署合约
合约写好后，点击上方的“Compile", 选择”ERC721", 最后点击”Deploy to the chain" 按钮。等待合约部署成功
合约部署成功后，会显示合约的交易id和合约地址。记下合约的地址，填表格的时候需要这个地址
创建NFT
找到mintToken这个函数，第一行输入收NFT的地址，第二行输入NFT的编号，最后一行输入NFT的图片链接（网上找个oasis的logo图）。输入好后，点击Transact，你的第一个NFT就创建好了
填表格
弄好合约后，如果你不想继续下面的挑战，可以直接填表格。表格链接：https://oasisprotocol.org/ch-oasis-eth-hackathon
在网站的中间那个位置，点击开始
厉害了
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你真是我们学习的偶像
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很厉害哦村长
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👍🏻厉害了
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