# ERC721AFacet ## ERC721AFacet \_Implementation of the [ERC721](https://eips.ethereum.org/EIPS/eip-721) Non-Fungible Token Standard, including the Metadata extension. Optimized for lower gas during batch mints. Token IDs are minted in sequential order (e.g. 0, 1, 2, 3, ...) starting from `_startTokenId()`. Assumptions: * An owner cannot have more than 2\*\*64 - 1 (max value of uint64) of supply. * The maximum token ID cannot exceed 2\*\*256 - 1 (max value of uint256).\_ ### totalSupply ```solidity function totalSupply() public view virtual returns (uint256) ``` \_Returns the total number of tokens in existence. Burned tokens will reduce the count. To get the total number of tokens minted, please see {*totalMinted}.* ### balanceOf ```solidity function balanceOf(address owner) public view virtual returns (uint256) ``` *Returns the number of tokens in `owner`'s account.* ### name ```solidity function name() public view virtual returns (string) ``` *Returns the token collection name.* ### symbol ```solidity function symbol() public view virtual returns (string) ``` *Returns the token collection symbol.* ### ownerOf ```solidity function ownerOf(uint256 tokenId) public view virtual returns (address) ``` \_Returns the owner of the `tokenId` token. Requirements: * `tokenId` must exist.\_ ### approve ```solidity function approve(address to, uint256 tokenId) public payable virtual ``` \_Gives permission to `to` to transfer `tokenId` token to another account. See {ERC721A-\_approve}. Requirements: * The caller must own the token or be an approved operator.\_ ### getApproved ```solidity function getApproved(uint256 tokenId) public view virtual returns (address) ``` \_Returns the account approved for `tokenId` token. Requirements: * `tokenId` must exist.\_ ### setApprovalForAll ```solidity function setApprovalForAll(address operator, bool approved) public virtual ``` \_Approve or remove `operator` as an operator for the caller. Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller. Requirements: * The `operator` cannot be the caller. Emits an {ApprovalForAll} event.\_ ### isApprovedForAll ```solidity function isApprovedForAll(address owner, address operator) public view virtual returns (bool) ``` \_Returns if the `operator` is allowed to manage all of the assets of `owner`. See {setApprovalForAll}.\_ ### transferFrom ```solidity function transferFrom(address from, address to, uint256 tokenId) public payable virtual ``` \_Transfers `tokenId` from `from` to `to`. Requirements: * `from` cannot be the zero address. * `to` cannot be the zero address. * `tokenId` token must be owned by `from`. * If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}. Emits a {Transfer} event.\_ ### safeTransferFrom ```solidity function safeTransferFrom(address from, address to, uint256 tokenId) public payable virtual ``` *Equivalent to `safeTransferFrom(from, to, tokenId, '')`.* ### safeTransferFrom ```solidity function safeTransferFrom(address from, address to, uint256 tokenId, bytes _data) public payable virtual ``` \_Safely transfers `tokenId` token from `from` to `to`. Requirements: * `from` cannot be the zero address. * `to` cannot be the zero address. * `tokenId` token must exist and be owned by `from`. * If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}. * If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer. Emits a {Transfer} event.\_ ### \_afterTokenTransfers ```solidity function _afterTokenTransfers(address from, address to, uint256 startTokenId, uint256 quantity) internal virtual ``` \_Hook that is called after a set of serially-ordered token IDs have been transferred. This includes minting. And also called after one token has been burned. `startTokenId` - the first token ID to be transferred. `quantity` - the amount to be transferred. Calling conditions: * When `from` and `to` are both non-zero, `from`'s `tokenId` has been transferred to `to`. * When `from` is zero, `tokenId` has been minted for `to`. * When `to` is zero, `tokenId` has been burned by `from`. * `from` and `to` are never both zero.\_ ### \_beforeTokenTransfers ```solidity function _beforeTokenTransfers(address from, address to, uint256 startTokenId, uint256 quantity) internal virtual ``` \_Hook that is called before a set of serially-ordered token IDs are about to be transferred. This includes minting. And also called before burning one token. `startTokenId` - the first token ID to be transferred. `quantity` - the amount to be transferred. Calling conditions: * When `from` and `to` are both non-zero, `from`'s `tokenId` will be transferred to `to`. * When `from` is zero, `tokenId` will be minted for `to`. * When `to` is zero, `tokenId` will be burned by `from`. * `from` and `to` are never both zero.\_ --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.roji.io/smart-contracts/api/erc721afacet.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. 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