TRC-721#
1 TRC-721 Protocol Standard#
TRC-721 is a set of standard interfaces, for issuing non-fungible tokens(NFT) on the TRON network. TRC-721 is fully compatible with ERC-721.
1.1 TRC-721 Smart Contract Interface Implementation#
Every TRC-721 compliant contract must implement the TRC721 and TRC165 interfaces. Other extension interfaces can be implemented according to specific business requirements.
1.1.1 TRC-721 & TRC-165 Interfaces#
Solidity
pragma solidity ^0.4.20;
interface TRC721 {
// Returns the number of NFTs owned by the given account
function balanceOf(address _owner) external view returns (uint256);
//Returns the owner of the given NFT
function ownerOf(uint256 _tokenId) external view returns (address);
//Transfer ownership of NFT
function safeTransferFrom(address _from, address _to, uint256 _tokenId, bytes data) external payable;
//Transfer ownership of NFT
function safeTransferFrom(address _from, address _to, uint256 _tokenId) external payable;
//Transfer ownership of NFT
function transferFrom(address _from, address _to, uint256 _tokenId) external payable;
//Grants address ‘_approved’ the authorization of the NFT ‘_tokenId’
function approve(address _approved, uint256 _tokenId) external payable;
//Grant/recover all NFTs’ authorization of the ‘_operator’
function setApprovalForAll(address _operator, bool _approved) external;
//Query the authorized address of NFT
function getApproved(uint256 _tokenId) external view returns (address);
//Query whether the ‘_operator’ is the authorized address of the ‘_owner’
function isApprovedForAll(address _owner, address _operator) external view returns (bool);
//The successful ‘transferFrom’ and ‘safeTransferFrom’ will trigger the ‘Transfer’ Event
event Transfer(address indexed _from, address indexed _to, uint256 indexed _tokenId);
//The successful ‘Approval’ will trigger the ‘Approval’ event
event Approval(address indexed _owner, address indexed _approved, uint256 indexed _tokenId);
//The successful ‘setApprovalForAll’ will trigger the ‘ApprovalForAll’ event
event ApprovalForAll(address indexed _owner, address indexed _operator, bool _approved);
}
interface TRC165 {
//Query whether the interface ‘interfaceID’ is supported
function supportsInterface(bytes4 interfaceID) external view returns (bool);
}
A wallet/broker/auction application MUST implement the wallet interface if it will accept safe transfers.
Solidity
interface TRC721TokenReceiver {
//This method will be triggered when the ‘_to’ is the contract address during the ‘safeTransferFrom’ execution, and the return value must be checked, If the return value is not bytes4(keccak256("onTRC721Received(address,address,uint256,bytes)")) throws an exception. The smart contract which can receive NFT must implement the TRC721TokenReceiver interface.
function onTRC721Received(address _operator, address _from, uint256 _tokenId, bytes _data) external returns(bytes4);
}
Note
The hash of bytes4(keccak256("onTRC721Received(address,address,uint256,bytes))) is different from the Ethereum version bytes4(keccak256("onERC721Received(address,address,uint256,bytes))). Please use 0x5175f878 instead of 0x150b7a02.
1.1.2 OPTIONAL Metadata Extension Interface#
The metadata extension is OPTIONAL for TRC-721 smart contracts. This allows your smart contract to be interrogated for its name and for details about the assets which your NFTs represent.
Solidity
interface TRC721Metadata {
//Return the token name
function name() external view returns (string _name);
//Return the token symbol
function symbol() external view returns (string _symbol);
//Returns the URI of the external file corresponding to ‘_tokenId’. External resource files need to include names, descriptions and pictures.
function tokenURI(uint256 _tokenId) external view returns (string);
}
URI is a URI link describing the _tokenId asset, pointing to a JSON file that conforms to the TRC721 metadata description structure. When tokens are minted, each token needs to be assigned a unique URI:
JSON
{
"title": "Asset Metadata",
"type": "object",
"properties": {
"name": {
"type": "string",
"description": "Identifies the asset to which this NFT represents"
},
"description": {
"type": "string",
"description": "Describes the asset to which this NFT represents"
},
"image": {
"type": "string",
"description": "A URI pointing to a resource with mime type image/* representing the asset to which this NFT represents. Consider making any images at a width between 320 and 1080 pixels and aspect ratio between 1.91:1 and 4:5 inclusive."
}
}
}
1.1.3 OPTIONAL Enumeration Extension Interface#
The enumeration extension is OPTIONAL for TRC-721 smart contracts. This allows your contract to publish its full list of NFTs and make them discoverable.
Solidity
interface TRC721Enumerable {
//Return the total supply of NFT
function totalSupply() external view returns (uint256);
//Return the corresponding ‘tokenId’ through ‘_index’
function tokenByIndex(uint256 _index) external view returns (uint256);
//Return the ‘tokenId’ corresponding to the index in the NFT list owned by the ‘_owner'
function tokenOfOwnerByIndex(address _owner, uint256 _index) external view returns (uint256);
}
Contract Example#
Solidity
pragma solidity ^0.5.0;
/**
* @dev Wrappers over Solidity's arithmetic operations with added overflow
* checks.
*
* Arithmetic operations in Solidity wrap on overflow. This can easily result
* in bugs, because programmers usually assume that an overflow raises an
* error, which is the standard behavior in high level programming languages.
* `SafeMath` restores this intuition by reverting the transaction when an
* operation overflows.
*
* Using this library instead of the unchecked operations eliminates an entire
* class of bugs, so it's recommended to use it always.
*/
library SafeMath {
/**
* @dev Returns the addition of two unsigned integers, reverting on
* overflow.
*
* Counterpart to Solidity's `+` operator.
*
* Requirements:
* - Addition cannot overflow.
*/
function add(uint256 a, uint256 b) internal pure returns (uint256) {
uint256 c = a + b;
require(c >= a, "SafeMath: addition overflow");
return c;
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting on
* overflow (when the result is negative).
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
* - Subtraction cannot overflow.
*/
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
return sub(a, b, "SafeMath: subtraction overflow");
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting with custom message on
* overflow (when the result is negative).
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
* - Subtraction cannot overflow.
*
* _Available since v2.4.0._
*/
function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b <= a, errorMessage);
uint256 c = a - b;
return c;
}
/**
* @dev Returns the multiplication of two unsigned integers, reverting on
* overflow.
*
* Counterpart to Solidity's `*` operator.
*
* Requirements:
* - Multiplication cannot 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-contracts/pull/522
if (a == 0) {
return 0;
}
uint256 c = a * b;
require(c / a == b, "SafeMath: multiplication overflow");
return c;
}
/**
* @dev Returns the integer division of two unsigned integers. Reverts on
* division by zero. The result is rounded towards zero.
*
* Counterpart to Solidity's `/` operator. Note: this function uses a
* `revert` opcode (which leaves remaining gas untouched) while Solidity
* uses an invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
* - The divisor cannot be zero.
*/
function div(uint256 a, uint256 b) internal pure returns (uint256) {
return div(a, b, "SafeMath: division by zero");
}
/**
* @dev Returns the integer division of two unsigned integers. Reverts with custom message on
* division by zero. The result is rounded towards zero.
*
* Counterpart to Solidity's `/` operator. Note: this function uses a
* `revert` opcode (which leaves remaining gas untouched) while Solidity
* uses an invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
* - The divisor cannot be zero.
*
* _Available since v2.4.0._
*/
function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
// Solidity only automatically asserts when dividing by 0
require(b > 0, errorMessage);
uint256 c = a / b;
// assert(a == b * c + a % b); // There is no case in which this doesn't hold
return c;
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* Reverts when dividing by zero.
*
* Counterpart to Solidity's `%` operator. This function uses a `revert`
* opcode (which leaves remaining gas untouched) while Solidity uses an
* invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
* - The divisor cannot be zero.
*/
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
return mod(a, b, "SafeMath: modulo by zero");
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* Reverts with custom message when dividing by zero.
*
* Counterpart to Solidity's `%` operator. This function uses a `revert`
* opcode (which leaves remaining gas untouched) while Solidity uses an
* invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
* - The divisor cannot be zero.
*
* _Available since v2.4.0._
*/
function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b != 0, errorMessage);
return a % b;
}
}
/*
* @dev Provides information about the current execution context, including the
* sender of the transaction and its data. While these are generally available
* via msg.sender and msg.data, they should not be accessed in such a direct
* manner, since when dealing with GSN meta-transactions the account sending and
* paying for execution may not be the actual sender (as far as an application
* is concerned).
*
* This contract is only required for intermediate, library-like contracts.
*/
contract Context {
// Empty internal constructor, to prevent people from mistakenly deploying
// an instance of this contract, which should be used via inheritance.
constructor () internal { }
// solhint-disable-previous-line no-empty-blocks
function _msgSender() internal view returns (address payable) {
return msg.sender;
}
function _msgData() internal view returns (bytes memory) {
this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
return msg.data;
}
}
/**
* @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(!has(role, account), "Roles: account already has role");
role.bearer[account] = true;
}
/**
* @dev Remove an account's access to this role.
*/
function remove(Role storage role, address account) internal {
require(has(role, account), "Roles: account does not have role");
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), "Roles: account is the zero address");
return role.bearer[account];
}
}
pragma solidity ^0.5.5;
/**
* @dev Collection of functions related to the address type
*/
library Address {
/**
* @dev Converts an `address` into `address payable`. Note that this is
* simply a type cast: the actual underlying value is not changed.
*
* _Available since v2.4.0._
*/
function toPayable(address account) internal pure returns (address payable) {
return address(uint160(account));
}
/**
* @dev Replacement for Solidity's `transfer`: sends `amount` wei to
* `recipient`, forwarding all available gas and reverting on errors.
*
* https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
*
* IMPORTANT: because control is transferred to `recipient`, care must be
* taken to not create reentrancy vulnerabilities. Consider using
* {ReentrancyGuard} or the
* https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
*
* _Available since v2.4.0._
*/
function sendValue(address payable recipient, uint256 amount) internal {
require(address(this).balance >= amount, "Address: insufficient balance");
// solhint-disable-next-line avoid-call-value
(bool success, ) = recipient.call.value(amount)("");
require(success, "Address: unable to send value, recipient may have reverted");
}
}
/**
* @title Counters
* @author Matt Condon (@shrugs)
* @dev Provides counters that can only be incremented or decremented by one. This can be used e.g. to track the number
* of elements in a mapping, issuing TRC721 ids, or counting request ids.
*
* Include with `using Counters for Counters.Counter;`
* Since it is not possible to overflow a 256 bit integer with increments of one, `increment` can skip the {SafeMath}
* overflow check, thereby saving gas. This does assume however correct usage, in that the underlying `_value` is never
* directly accessed.
*/
library Counters {
using SafeMath for uint256;
struct Counter {
// This variable should never be directly accessed by users of the library: interactions must be restricted to
// the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
// this feature: see https://github.com/ethereum/solidity/issues/4637
uint256 _value; // default: 0
}
function current(Counter storage counter) internal view returns (uint256) {
return counter._value;
}
function increment(Counter storage counter) internal {
// The {SafeMath} overflow check can be skipped here, see the comment at the top
counter._value += 1;
}
function decrement(Counter storage counter) internal {
counter._value = counter._value.sub(1);
}
}
contract MinterRole is Context {
using Roles for Roles.Role;
event MinterAdded(address indexed account);
event MinterRemoved(address indexed account);
Roles.Role private _minters;
constructor () internal {
_addMinter(_msgSender());
}
modifier onlyMinter() {
require(isMinter(_msgSender()), "MinterRole: caller does not have the Minter role");
_;
}
function isMinter(address account) public view returns (bool) {
return _minters.has(account);
}
function addMinter(address account) public onlyMinter {
_addMinter(account);
}
function renounceMinter() public {
_removeMinter(_msgSender());
}
function _addMinter(address account) internal {
_minters.add(account);
emit MinterAdded(account);
}
function _removeMinter(address account) internal {
_minters.remove(account);
emit MinterRemoved(account);
}
}
/**
* @dev Interface of the TRC165 standard.
*
* Implementers can declare support of contract interfaces, which can then be
* queried by others ({TRC165Checker}).
*
* For an implementation, see {TRC165}.
*/
interface ITRC165 {
/**
* @dev Returns true if this contract implements the interface defined by
* `interfaceId`.
*
* This function call must use less than 30 000 gas.
*/
function supportsInterface(bytes4 interfaceId) external view returns (bool);
}
/**
* @dev Required interface of an TRC721 compliant contract.
*/
contract ITRC721 is ITRC165 {
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);
/**
* @dev Returns the number of NFTs in `owner`'s account.
*/
function balanceOf(address owner) public view returns (uint256 balance);
/**
* @dev Returns the owner of the NFT specified by `tokenId`.
*/
function ownerOf(uint256 tokenId) public view returns (address owner);
/**
* @dev Transfers a specific NFT (`tokenId`) from one account (`from`) to
* another (`to`).
*
*
*
* Requirements:
* - `from`, `to` cannot be zero.
* - `tokenId` must be owned by `from`.
* - If the caller is not `from`, it must be have been allowed to move this
* NFT by either {approve} or {setApprovalForAll}.
*/
function safeTransferFrom(address from, address to, uint256 tokenId) public;
/**
* @dev Transfers a specific NFT (`tokenId`) from one account (`from`) to
* another (`to`).
*
* Requirements:
* - If the caller is not `from`, it must be approved to move this NFT by
* either {approve} or {setApprovalForAll}.
*/
function transferFrom(address from, address to, uint256 tokenId) public;
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 safeTransferFrom(address from, address to, uint256 tokenId, bytes memory data) public;
}
/**
* @title TRC-721 Non-Fungible Token Standard, optional metadata extension
*/
contract ITRC721Metadata is ITRC721 {
function name() external view returns (string memory);
function symbol() external view returns (string memory);
function tokenURI(uint256 tokenId) external view returns (string memory);
}
/**
* @title TRC721 token receiver interface
* @dev Interface for any contract that wants to support safeTransfers
* from TRC721 asset contracts.
*/
contract ITRC721Receiver {
/**
* @notice Handle the receipt of an NFT
* @dev The TRC721 smart contract calls this function on the recipient
* after a {ITRC721-safeTransferFrom}. This function MUST return the function selector,
* otherwise the caller will revert the transaction. The selector to be
* returned can be obtained as `this.onTRC721Received.selector`. This
* function MAY throw to revert and reject the transfer.
* Note: the TRC721 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 `bytes4(keccak256("onTRC721Received(address,address,uint256,bytes)"))`
*/
function onTRC721Received(address operator, address from, uint256 tokenId, bytes memory data)
public returns (bytes4);
}
/**
* @dev Implementation of the {ITRC165} interface.
*
* Contracts may inherit from this and call {_registerInterface} to declare
* their support of an interface.
*/
contract TRC165 is ITRC165 {
/*
* bytes4(keccak256('supportsInterface(bytes4)')) == 0x01ffc9a7
*/
bytes4 private constant _INTERFACE_ID_TRC165 = 0x01ffc9a7;
/**
* @dev Mapping of interface ids to whether or not it's supported.
*/
mapping(bytes4 => bool) private _supportedInterfaces;
constructor () internal {
// Derived contracts need only register support for their own interfaces,
// we register support for TRC165 itself here
_registerInterface(_INTERFACE_ID_TRC165);
}
/**
* @dev See {ITRC165-supportsInterface}.
*
* Time complexity O(1), guaranteed to always use less than 30 000 gas.
*/
function supportsInterface(bytes4 interfaceId) external view returns (bool) {
return _supportedInterfaces[interfaceId];
}
/**
* @dev Registers the contract as an implementer of the interface defined by
* `interfaceId`. Support of the actual TRC165 interface is automatic and
* registering its interface id is not required.
*
* See {ITRC165-supportsInterface}.
*
* Requirements:
*
* - `interfaceId` cannot be the TRC165 invalid interface (`0xffffffff`).
*/
function _registerInterface(bytes4 interfaceId) internal {
require(interfaceId != 0xffffffff, "TRC165: invalid interface id");
_supportedInterfaces[interfaceId] = true;
}
}
/**
* @title TRC721 Non-Fungible Token Standard basic implementation
*/
contract TRC721 is Context, TRC165, ITRC721 {
using SafeMath for uint256;
using Address for address;
using Counters for Counters.Counter;
// Equals to `bytes4(keccak256("onTRC721Received(address,address,uint256,bytes)"))`
// which can be also obtained as `ITRC721Receiver(0).onTRC721Received.selector`
//
// NOTE: TRC721 uses 0x150b7a02, TRC721 uses 0x5175f878.
bytes4 private constant _TRC721_RECEIVED = 0x5175f878;
// 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 => Counters.Counter) private _ownedTokensCount;
// Mapping from owner to operator approvals
mapping (address => mapping (address => bool)) private _operatorApprovals;
/*
* bytes4(keccak256('balanceOf(address)')) == 0x70a08231
* bytes4(keccak256('ownerOf(uint256)')) == 0x6352211e
* bytes4(keccak256('approve(address,uint256)')) == 0x095ea7b3
* bytes4(keccak256('getApproved(uint256)')) == 0x081812fc
* bytes4(keccak256('setApprovalForAll(address,bool)')) == 0xa22cb465
* bytes4(keccak256('isApprovedForAll(address,address)')) == 0xe985e9c5
* bytes4(keccak256('transferFrom(address,address,uint256)')) == 0x23b872dd
* bytes4(keccak256('safeTransferFrom(address,address,uint256)')) == 0x42842e0e
* bytes4(keccak256('safeTransferFrom(address,address,uint256,bytes)')) == 0xb88d4fde
*
* => 0x70a08231 ^ 0x6352211e ^ 0x095ea7b3 ^ 0x081812fc ^
* 0xa22cb465 ^ 0xe985e9c ^ 0x23b872dd ^ 0x42842e0e ^ 0xb88d4fde == 0x80ac58cd
*/
bytes4 private constant _INTERFACE_ID_TRC721 = 0x80ac58cd;
constructor () public {
// register the supported interfaces to conform to TRC721 via TRC165
_registerInterface(_INTERFACE_ID_TRC721);
}
/**
* @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), "TRC721: balance query for the zero address");
return _ownedTokensCount[owner].current();
}
/**
* @dev Gets the owner of the specified token ID.
* @param tokenId uint256 ID of the token to query the owner of
* @return 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), "TRC721: owner query for nonexistent token");
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, "TRC721: approval to current owner");
require(_msgSender() == owner || isApprovedForAll(owner, _msgSender()),
"TRC721: approve caller is not owner nor approved for all"
);
_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), "TRC721: approved query for nonexistent token");
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 != _msgSender(), "TRC721: approve to caller");
_operatorApprovals[_msgSender()][to] = approved;
emit ApprovalForAll(_msgSender(), 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 {
//solhint-disable-next-line max-line-length
require(_isApprovedOrOwner(_msgSender(), tokenId), "TRC721: transfer caller is not owner nor approved");
_transferFrom(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 {ITRC721Receiver-onTRC721Received},
* which is called upon a safe transfer, and return the magic value
* `bytes4(keccak256("onTRC721Received(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 {
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 {ITRC721Receiver-onTRC721Received},
* which is called upon a safe transfer, and return the magic value
* `bytes4(keccak256("onTRC721Received(address,address,uint256,bytes)"))`; otherwise,
* the transfer is reverted.
* Requires the _msgSender() 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 memory _data) public {
require(_isApprovedOrOwner(_msgSender(), tokenId), "TRC721: transfer caller is not owner nor approved");
_safeTransferFrom(from, to, tokenId, _data);
}
/**
* @dev Safely transfers the ownership of a given token ID to another address
* If the target address is a contract, it must implement `onTRC721Received`,
* which is called upon a safe transfer, and return the magic value
* `bytes4(keccak256("onTRC721Received(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 memory _data) internal {
_transferFrom(from, to, tokenId);
require(_checkOnTRC721Received(from, to, tokenId, _data), "TRC721: transfer to non TRC721Receiver implementer");
}
/**
* @dev Returns whether the specified token exists.
* @param tokenId uint256 ID of the token to query the existence of
* @return bool 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) {
require(_exists(tokenId), "TRC721: operator query for nonexistent token");
address owner = ownerOf(tokenId);
return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
}
/**
* @dev Internal function to safely mint a new token.
* Reverts if the given token ID already exists.
* If the target address is a contract, it must implement `onTRC721Received`,
* which is called upon a safe transfer, and return the magic value
* `bytes4(keccak256("onTRC721Received(address,address,uint256,bytes)"))`; otherwise,
* the transfer is reverted.
* @param to The address that will own the minted token
* @param tokenId uint256 ID of the token to be minted
*/
function _safeMint(address to, uint256 tokenId) internal {
_safeMint(to, tokenId, "");
}
/**
* @dev Internal function to safely mint a new token.
* Reverts if the given token ID already exists.
* If the target address is a contract, it must implement `onTRC721Received`,
* which is called upon a safe transfer, and return the magic value
* `bytes4(keccak256("onTRC721Received(address,address,uint256,bytes)"))`; otherwise,
* the transfer is reverted.
* @param to The address that will own the minted token
* @param tokenId uint256 ID of the token to be minted
* @param _data bytes data to send along with a safe transfer check
*/
function _safeMint(address to, uint256 tokenId, bytes memory _data) internal {
_mint(to, tokenId);
require(_checkOnTRC721Received(address(0), to, tokenId, _data), "TRC721: transfer to non TRC721Receiver implementer");
}
/**
* @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
*/
function _mint(address to, uint256 tokenId) internal {
require(to != address(0), "TRC721: mint to the zero address");
require(!_exists(tokenId), "TRC721: token already minted");
_tokenOwner[tokenId] = to;
_ownedTokensCount[to].increment();
emit Transfer(address(0), to, tokenId);
}
/**
* @dev Internal function to burn a specific token.
* Reverts if the token does not exist.
* Deprecated, use {_burn} instead.
* @param owner owner of the token to burn
* @param tokenId uint256 ID of the token being burned
*/
function _burn(address owner, uint256 tokenId) internal {
require(ownerOf(tokenId) == owner, "TRC721: burn of token that is not own");
_clearApproval(tokenId);
_ownedTokensCount[owner].decrement();
_tokenOwner[tokenId] = address(0);
emit Transfer(owner, address(0), 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
*/
function _burn(uint256 tokenId) internal {
_burn(ownerOf(tokenId), tokenId);
}
/**
* @dev Internal function to transfer ownership of a given token ID to another address.
* As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
* @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) internal {
require(ownerOf(tokenId) == from, "TRC721: transfer of token that is not own");
require(to != address(0), "TRC721: transfer to the zero address");
_clearApproval(tokenId);
_ownedTokensCount[from].decrement();
_ownedTokensCount[to].increment();
_tokenOwner[tokenId] = to;
emit Transfer(from, to, tokenId);
}
/**
* @dev Internal function to invoke {ITRC721Receiver-onTRC721Received} on a target address.
* The call is not executed if the target address is not a contract.
*
* This is an internal detail of the `TRC721` contract and its use is deprecated.
* @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 bool whether the call correctly returned the expected magic value
*/
function _checkOnTRC721Received(address from, address to, uint256 tokenId, bytes memory _data)
internal returns (bool)
{
if (!to.isContract) {
return true;
}
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = to.call(abi.encodeWithSelector(
ITRC721Receiver(to).onTRC721Received.selector,
_msgSender(),
from,
tokenId,
_data
));
if (!success) {
if (returndata.length > 0) {
// solhint-disable-next-line no-inline-assembly
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert("TRC721: transfer to non TRC721Receiver implementer");
}
} else {
bytes4 retval = abi.decode(returndata, (bytes4));
return (retval == _TRC721_RECEIVED);
}
}
/**
* @dev Private function to clear current approval of a given token ID.
* @param tokenId uint256 ID of the token to be transferred
*/
function _clearApproval(uint256 tokenId) private {
if (_tokenApprovals[tokenId] != address(0)) {
_tokenApprovals[tokenId] = address(0);
}
}
}
contract TRC721Metadata is Context, TRC165, TRC721, ITRC721Metadata {
// Token name
string private _name;
// Token symbol
string private _symbol;
// Base URI
string private _baseURI;
// Optional mapping for token URIs
mapping(uint256 => string) private _tokenURIs;
/*
* bytes4(keccak256('name()')) == 0x06fdde03
* bytes4(keccak256('symbol()')) == 0x95d89b41
* bytes4(keccak256('tokenURI(uint256)')) == 0xc87b56dd
*
* => 0x06fdde03 ^ 0x95d89b41 ^ 0xc87b56dd == 0x5b5e139f
*/
bytes4 private constant _INTERFACE_ID_TRC721_METADATA = 0x5b5e139f;
/**
* @dev Constructor function
*/
constructor (string memory name, string memory symbol) public {
_name = name;
_symbol = symbol;
// register the supported interfaces to conform to TRC721 via TRC165
_registerInterface(_INTERFACE_ID_TRC721_METADATA);
}
/**
* @dev Gets the token name.
* @return string representing the token name
*/
function name() external view returns (string memory) {
return _name;
}
/**
* @dev Gets the token symbol.
* @return string representing the token symbol
*/
function symbol() external view returns (string memory) {
return _symbol;
}
/**
* @dev Returns the URI for a given token ID. May return an empty string.
*
* If the token's URI is non-empty and a base URI was set (via
* {_setBaseURI}), it will be added to the token ID's URI as a prefix.
*
* Reverts if the token ID does not exist.
*/
function tokenURI(uint256 tokenId) external view returns (string memory) {
require(_exists(tokenId), "TRC721Metadata: URI query for nonexistent token");
string memory _tokenURI = _tokenURIs[tokenId];
// Even if there is a base URI, it is only appended to non-empty token-specific URIs
if (bytes(_tokenURI).length == 0) {
return "";
} else {
// abi.encodePacked is being used to concatenate strings
return string(abi.encodePacked(_baseURI, _tokenURI));
}
}
/**
* @dev Internal function to set the token URI for a given token.
*
* Reverts if the token ID does not exist.
*
* TIP: if all token IDs share a prefix (e.g. if your URIs look like
* `http://api.myproject.com/token/<id>`), use {_setBaseURI} to store
* it and save gas.
*/
function _setTokenURI(uint256 tokenId, string memory _tokenURI) internal {
require(_exists(tokenId), "TRC721Metadata: URI set of nonexistent token");
_tokenURIs[tokenId] = _tokenURI;
}
/**
* @dev Internal function to set the base URI for all token IDs. It is
* automatically added as a prefix to the value returned in {tokenURI}.
*
* _Available since v2.5.0._
*/
function _setBaseURI(string memory baseURI) internal {
_baseURI = baseURI;
}
/**
* @dev Returns the base URI set via {_setBaseURI}. This will be
* automatically added as a preffix in {tokenURI} to each token's URI, when
* they are non-empty.
*
* _Available since v2.5.0._
*/
function baseURI() external view returns (string memory) {
return _baseURI;
}
/**
* @dev Internal function to burn a specific token.
* Reverts if the token does not exist.
* Deprecated, use _burn(uint256) instead.
* @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];
}
}
}
/**
* @title TRC721MetadataMintable
* @dev TRC721 minting logic with metadata.
*/
contract TRC721MetadataMintable is TRC721, TRC721Metadata, MinterRole {
/**
* @dev Function to mint tokens.
* @param to The address that will receive the minted tokens.
* @param tokenId The token id to mint.
* @param tokenURI The token URI of the minted token.
* @return A boolean that indicates if the operation was successful.
*/
function mintWithTokenURI(address to, uint256 tokenId, string memory tokenURI) public onlyMinter returns (bool) {
_mint(to, tokenId);
_setTokenURI(tokenId, tokenURI);
return true;
}
}
/**
* @title TRC721Mintable
* @dev TRC721 minting logic.
*/
contract TRC721Mintable is TRC721, MinterRole {
/**
* @dev Function to mint tokens.
* @param to The address that will receive the minted token.
* @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;
}
/**
* @dev Function to safely mint tokens.
* @param to The address that will receive the minted token.
* @param tokenId The token id to mint.
* @return A boolean that indicates if the operation was successful.
*/
function safeMint(address to, uint256 tokenId) public onlyMinter returns (bool) {
_safeMint(to, tokenId);
return true;
}
/**
* @dev Function to safely mint tokens.
* @param to The address that will receive the minted token.
* @param tokenId The token id to mint.
* @param _data bytes data to send along with a safe transfer check.
* @return A boolean that indicates if the operation was successful.
*/
function safeMint(address to, uint256 tokenId, bytes memory _data) public onlyMinter returns (bool) {
_safeMint(to, tokenId, _data);
return true;
}
}
/**
* @title TRC-721 Non-Fungible Token Standard, optional enumeration extension
*/
contract ITRC721Enumerable is ITRC721 {
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);
}
/**
* @title TRC-721 Non-Fungible Token with optional enumeration extension logic
*/
contract TRC721Enumerable is Context, TRC165, TRC721, ITRC721Enumerable {
// 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(keccak256('totalSupply()')) == 0x18160ddd
* bytes4(keccak256('tokenOfOwnerByIndex(address,uint256)')) == 0x2f745c59
* bytes4(keccak256('tokenByIndex(uint256)')) == 0x4f6ccce7
*
* => 0x18160ddd ^ 0x2f745c59 ^ 0x4f6ccce7 == 0x780e9d63
*/
bytes4 private constant _INTERFACE_ID_TRC721_ENUMERABLE = 0x780e9d63;
/**
* @dev Constructor function.
*/
constructor () public {
// register the supported interface to conform to TRC721Enumerable via TRC165
_registerInterface(_INTERFACE_ID_TRC721_ENUMERABLE);
}
/**
* @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), "TRC721Enumerable: owner index out of bounds");
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(), "TRC721Enumerable: global index out of bounds");
return _allTokens[index];
}
/**
* @dev Internal function to transfer ownership of a given token ID to another address.
* As opposed to transferFrom, this imposes no restrictions on msg.sender.
* @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) internal {
super._transferFrom(from, to, tokenId);
_removeTokenFromOwnerEnumeration(from, tokenId);
_addTokenToOwnerEnumeration(to, tokenId);
}
/**
* @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
*/
function _mint(address to, uint256 tokenId) internal {
super._mint(to, tokenId);
_addTokenToOwnerEnumeration(to, tokenId);
_addTokenToAllTokensEnumeration(tokenId);
}
/**
* @dev Internal function to burn a specific token.
* Reverts if the token does not exist.
* Deprecated, use {TRC721-_burn} instead.
* @param owner owner of the token to burn
* @param tokenId uint256 ID of the token being burned
*/
function _burn(address owner, uint256 tokenId) internal {
super._burn(owner, tokenId);
_removeTokenFromOwnerEnumeration(owner, tokenId);
// Since tokenId will be deleted, we can clear its slot in _ownedTokensIndex to trigger a gas refund
_ownedTokensIndex[tokenId] = 0;
_removeTokenFromAllTokensEnumeration(tokenId);
}
/**
* @dev Gets the list of token IDs of the requested owner.
* @param owner address owning the tokens
* @return uint256[] List of token IDs owned by the requested address
*/
function _tokensOfOwner(address owner) internal view returns (uint256[] storage) {
return _ownedTokens[owner];
}
/**
* @dev Private function to add a token to this extension's ownership-tracking data structures.
* @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 _addTokenToOwnerEnumeration(address to, uint256 tokenId) private {
_ownedTokensIndex[tokenId] = _ownedTokens[to].length;
_ownedTokens[to].push(tokenId);
}
/**
* @dev Private function to add a token to this extension's token tracking data structures.
* @param tokenId uint256 ID of the token to be added to the tokens list
*/
function _addTokenToAllTokensEnumeration(uint256 tokenId) private {
_allTokensIndex[tokenId] = _allTokens.length;
_allTokens.push(tokenId);
}
/**
* @dev Private function to remove a token from this extension's ownership-tracking data structures. Note that
* while the token is not assigned a new owner, the `_ownedTokensIndex` mapping is _not_ updated: this allows for
* gas optimizations e.g. when performing a transfer operation (avoiding double writes).
* This has O(1) time complexity, but alters the order of the _ownedTokens array.
* @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 _removeTokenFromOwnerEnumeration(address from, uint256 tokenId) private {
// To prevent a gap in from's tokens array, we store the last token in the index of the token to delete, and
// then delete the last slot (swap and pop).
uint256 lastTokenIndex = _ownedTokens[from].length.sub(1);
uint256 tokenIndex = _ownedTokensIndex[tokenId];
// When the token to delete is the last token, the swap operation is unnecessary
if (tokenIndex != lastTokenIndex) {
uint256 lastTokenId = _ownedTokens[from][lastTokenIndex];
_ownedTokens[from][tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
_ownedTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index
}
// This also deletes the contents at the last position of the array
_ownedTokens[from].length--;
// Note that _ownedTokensIndex[tokenId] hasn't been cleared: it still points to the old slot (now occupied by
// lastTokenId, or just over the end of the array if the token was the last one).
}
/**
* @dev Private function to remove a token from this extension's token tracking data structures.
* This has O(1) time complexity, but alters the order of the _allTokens array.
* @param tokenId uint256 ID of the token to be removed from the tokens list
*/
function _removeTokenFromAllTokensEnumeration(uint256 tokenId) private {
// To prevent a gap in the tokens array, we store the last token in the index of the token to delete, and
// then delete the last slot (swap and pop).
uint256 lastTokenIndex = _allTokens.length.sub(1);
uint256 tokenIndex = _allTokensIndex[tokenId];
// When the token to delete is the last token, the swap operation is unnecessary. However, since this occurs so
// rarely (when the last minted token is burnt) that we still do the swap here to avoid the gas cost of adding
// an 'if' statement (like in _removeTokenFromOwnerEnumeration)
uint256 lastTokenId = _allTokens[lastTokenIndex];
_allTokens[tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
_allTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index
// This also deletes the contents at the last position of the array
_allTokens.length--;
_allTokensIndex[tokenId] = 0;
}
}
contract TRC721Token is TRC721, TRC721Enumerable, TRC721MetadataMintable {
constructor() public TRC721Metadata("Your Token Name", "YTN") {
}
}
TRC-721 Token Issuance#
1 Create a TRON Account#
Install the Chrome extension of TronLink to get ready for your issuance. You may create a new account in three ways:
create a new account
restoring from a mnemonic phrase, private key or Keystore
connect to a hardware wallet
350 TRX is required in your account as the minimum.
2 TRC-721 Code Modification#
You may modify the file of TRC721Token.sol to customise the name and symbol of the token. Remember to save your changes.
TRC-721 contract template: template
3 Deploy a TRC-721 Smart Contract#
Deploy with tronscan: Contract Compiler
3.1 Connect to the Wallet#
3.2 Upload Contract Codes#
3.3 Compile the Contract#
Please choose the compiler version between 0.5.14 and 0.5.5
Click ‘Confirm’ to compile. Compilation succeeds with this:
3.4 Deploy the Contract#
Remember to choose TRC721Token, for it is the main contract.
Click Confirm to deploy. There will be a pop-up from TronLink, click Accept to sign.
4 Minting an NFT Token#
Log in to Tronscan with your wallet, and use the contract address to open the deployed TRC-721 contract. Here, take the TZ4NjvdqyCbWmZxXEEAb3bXhfT8f6YGxJd contract on the Nile test net as an example:
-
Choose 'Contract', 'Write Contract'
-
Find the mintWithTokenURI method, fill in the to_address, tokenId, and the tokenURI corresponding to coral.json
Metadata URI
有?metadata URI的生成，参照上?Metadata到BTFS网?。
Refer to [Uploading NFT MEtadata to BTFS Network](https://developers.tron.network/docs/uploading-nft-metadata-to-the-btfs-network "Uploading NFT MEtadata to BTFS Network") for the generation of metadata URI.
- Click 'send', then accept the signature. A 'true' will be displayed if the token was mint successfully
TRC-721 Contract Interaction#
1 Query the Token Name#
Call the function ‘name()’ of TRC-721 to get the token name.
Shell
curl -X POST https://api.shasta.trongrid.io/wallet/triggersmartcontract -d '{
"contract_address":"418c921721ababd66313981e1ad49b19c4e799f24d",
"function_selector":"name()",
"owner_address":"411fafb1e96dfe4f609e2259bfaf8c77b60c535b93"
}'
Result:
Shell
Result:
{"result":{"result":true},"constant_result":["0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000f596f757220546f6b656e204e616d650000000000000000000000000000000000"],"transaction":{"ret":[{}],"visible":false,"txID":"418a8fe76cb888e06c68cbe6a7c52b3b6f9c009877e16a2a87183868c5cbb1b0","raw_data":{"contract":[{"parameter":{"value":{"data":"06fdde03","owner_address":"411fafb1e96dfe4f609e2259bfaf8c77b60c535b93","contract_address":"418c921721ababd66313981e1ad49b19c4e799f24d"},"type_url":"type.googleapis.com/protocol.TriggerSmartContract"},"type":"TriggerSmartContract"}],"ref_block_bytes":"2d6d","ref_block_hash":"08e5816e980173a0","expiration":1615822557000,"fee_limit":400000000,"timestamp":1615822500321},"raw_data_hex":"0a022d6d220808e5816e980173a040c89e9eb4832f5a6d081f12690a31747970652e676f6f676c65617069732e636f6d2f70726f746f636f6c2e54726967676572536d617274436f6e747261637412340a15411fafb1e96dfe4f609e2259bfaf8c77b60c535b931215418c921721ababd66313981e1ad49b19c4e799f24d220406fdde0370e1e39ab4832f90018088debe01"}}
The name of the token is included in constant_result, returned with the format of hex string.
Since the return value is string type, string in the virtual machine is considered to be a variable-length type. Its data contains two parts: length and actual value. Therefore, the above return value needs to be parsed into three parts, which is split every 32 bytes.
0000000000000000000000000000000000000000000000000000000000000020 pointer
000000000000000000000000000000000000000000000000000000000000000F length
596F757220546F6b656e204e616d650000000000000000000000000000000000 real value
Parsed to semantics, the string data is read from the 32nd byte (20 in hexadecimal represents 32 in decimal), and the length is 15 bytes. The actual data is "596F757220546F6b656e204e616d65". convert it into a string form is "Your Token Name".
2 Query the Token Symbol#
Shell
curl -X POST https://api.shasta.trongrid.io/wallet/triggersmartcontract -d '{
"contract_address":"418c921721ababd66313981e1ad49b19c4e799f24d",
"function_selector":"symbol()",
"owner_address":"411fafb1e96dfe4f609e2259bfaf8c77b60c535b93"
}'
The symbol of the token is included in constant_result(YTN), returned with the format of hex string.
The parsing process is similar to the name() method above, please refer to the detailed explanation of name().
3 Query the Balance#
Shell
curl -X POST https://api.shasta.trongrid.io/wallet/triggersmartcontract -d '{
"contract_address":"419E62BE7F4F103C36507CB2A753418791B1CDC182",
"function_selector":"balanceOf(address)",
"parameter":"000000000000000000000041977C20977F412C2A1AA4EF3D49FEE5EC4C31CDFB",
"owner_address":"41977C20977F412C2A1AA4EF3D49FEE5EC4C31CDFB"
}'
Parameters:
Contract_address: contract address in hex string
Owner_address: the account address which triggers the contract function in hex string
Function_selector: the function to be called
Parameters need to be passed to the contract methods. In this case, the address should be passed in. In this case, the address should be passed in. Since the address structure of TRON is the address prefix "41" + 20-byte address, 32 bytes are required when the address parameters are transmitted, so fill it with "0" in front.
4 NFT Transfer#
Shell
curl -X POST https://api.shasta.trongrid.io/wallet/triggersmartcontract -d '{
"contract_address":"419E62BE7F4F103C36507CB2A753418791B1CDC182",
"fee_limit": 400000000,
"function_selector":"transferFrom(address,address,uint256)",
"parameter":"0000000000000000000000001fafb1e96dfe4f609e2259bfaf8c77b60c535b9300000000000000000000000021ae4e504e68a75521221163faae1acd01deb3160000000000000000000000000000000000000000000000000000000000000001",
"call_value":0,
"owner_address":"419E62BE7F4F103C36507CB2A753418791B1CDC182"
}'
The parameter is to encode the address and uint256 in transfer(address,uint256), please refer to the parameter encoding and decoding document for details.
Note
After calling this HTTP API, signing and broadcast APIs should also be called.
Reference of transaction confirmation: How to Confirm a Transaction
5 Approve the Control of an NFT to Another Address#
Shell
curl -X POST https://api.shasta.trongrid.io/wallet/triggersmartcontract -d '{
"contract_address":"419E62BE7F4F103C36507CB2A753418791B1CDC182",
"fee_limit": 400000000,
"function_selector":"approve(address,uint256)",
"parameter":"000000000000000000000000173ebb4f23dbdc69f31065d7f8d2dacab32e004f0000000000000000000000000000000000000000000000000000000000000001",
"call_value":0,
"owner_address":"419E62BE7F4F103C36507CB2A753418791B1CDC182"
}'
The parameter is to encode the address and uint256 in transfer(address,uint256), please refer to the parameter encoding and decoding document for details.
Note
After calling this HTTP API, signing and broadcast APIs should also be called.
Reference of transaction confirmation: How to Confirm a Transaction
6 Query All NFT information of a TRC-721 Contract of a Specific Address#
- Call the function of balanceOf(address _owner) to query the number of NFT holdings
- Call the function of tokenOfOwnerByIndex(address _owner, uint256 _index) to traverse all token_ids
- Call the function of tokenURI(uint256 _tokenId) to query the details of every NFT.
Uploading NFT Metadata to BTFS Network#
BitTorrent File System (BTFS) is a next-generation file-sharing protocol utilizing the TRON network and the BitTorrent ecosystem.
Metadata is the detailed information of the NFT token. It is stored off the chain. Generally, the issuance of an NFT token will specify a URI path that points to the Metadata data of the token.
1 Install BTFS#
Refer to BTFS Installation Instructions..
2 Deposit BTT#
Uploading files to the BTFS network requires BTT as the payment method.
The current storage price is 0.0037 BTT/Mb/month. For the uploader, redundant information will be added to the uploaded file and split into 30 copies. Any ten copies can be restored into a complete file so that each file will be uploaded three times the original file size. That is, for the uploader, the price is 3*0.0037 BTT/Mb/month(about $0.000038/Mb/month, calculated with the current price).
While using btfs init to initialize the local node, the command will generate a TRON wallet account associated with the node. You can check the TRON address corresponding to the wallet through btfs id.
First, you need to recharge some BTT to the node's TRON account and then transfer the BTT of the TRON account to the accounting system of the BTFS network.
Set a Password#
Run the following command to set a password for the node wallet:
Shell
btfs wallet password **********
Transfer BTT to BTFS network accounting system#
Running the following command will transfer the BTT of the local BTFS node account to the accounting system of the BTFS network. The minimum transfer amount is 10 BTT, and the BTT unit specified in the following command is μBTT (1/1000000 of BTT):
Shell
btfs wallet deposit -p ********* 10000000
3 Upload the File#
Step 1: Prepare a picture and name the picture coral.jpeg#
Step 2: Use Reed-Solomon encoding to add pictures to the local node#
Shell
btfs add --chunker=reed-solomon coral.jpeg
The QmUK9nwtLEiHBJ48HAZHNmSQ53U6ADbRhATxs2tomadwKw in the picture is the hash value of the file.
Step 3: Upload files to the BTFS network through this hash value:#
Shell
btfs storage upload QmUK9nwtLEiHBJ48HAZHNmSQ53U6ADbRhATxs2tomadwKw
When you see "File storage successful" in the window of btfs daemon, it means the upload is successful
Step 4: Verify that the picture can be downloaded#
Open the following link of the picture in the browser, you can see the picture indicating that the picture can be downloaded successfully:
https://gateway.btfs.io/btfs/QmUK9nwtLEiHBJ48HAZHNmSQ53U6ADbRhATxs2tomadwKw
4 Construct the NFT metadata file#
You can use the image link above to construct metadata for NFT.
Create a JSON file according to the metadata example in the TRC-721 document and name it coral.json, and replace the description value in the image field with the BTFS download link of the image above, as shown in the figure:
Run the btfs command to upload coral.json:
Open the URI of the metadata file in the browser: https://gateway.btfs.io/btfs/QmWq4cp588QD8tzrSxvPs2bGikDdKyA35BT3iysBcP1jFD
