ERC721

Reference of interfaces, presets, and utilities related to ERC721 contracts.

For an overview of ERC721, read our ERC721 guide.

Core

IERC721 

use openzeppelin::token::erc721::interface::IERC721;

Interface of the IERC721 standard as defined in EIP721.

SRC5 ID

0x33eb2f84c309543403fd69f0d0f363781ef06ef6faeb0131ff16ea3175bd943

Functions
Events

Functions

balance_of(account: ContractAddress) → u256 external

Returns the number of NFTs owned by account.

owner_of(token_id: u256) → ContractAddress external

Returns the owner address of token_id.

safe_transfer_from(from: ContractAddress, to: ContractAddress, token_id: u256, data: Span<felt252>) external

Transfer ownership of token_id from from to to, checking first that to is aware of the ERC721 protocol to prevent tokens being locked forever. For information regarding how contracts communicate their awareness of the ERC721 protocol, see Receiving Tokens.

Emits a Transfer event.

transfer_from(from: ContractAddress, to: ContractAddress, token_id: u256) external

Transfer ownership of token_id from from to to.

Note that the caller is responsible to confirm that the recipient is capable of receiving ERC721 transfers or else they may be permanently lost. Usage of IERC721::safe_transfer_from prevents loss, though the caller must understand this adds an external call which potentially creates a reentrancy vulnerability.

Emits a Transfer event.

approve(to: ContractAddress, token_id: u256) external

Change or reaffirm the approved address for an NFT.

Emits an Approval event.

set_approval_for_all(operator: ContractAddress, approved: bool) external

Enable or disable approval for operator to manage all of the caller’s assets.

Emits an ApprovalForAll event.

get_approved(token_id: u256) -> u256 external

Returns the address approved for token_id.

is_approved_for_all(owner: ContractAddress, operator: ContractAddress) -> bool external

Query if operator is an authorized operator for owner.

Events

Approval(owner: ContractAddress, approved: ContractAddress, token_id: u256) event

Emitted when owner enables approved to manage the token_id token.

ApprovalForAll(owner: ContractAddress, operator: ContractAddress, approved: bool) event

Emitted when owner enables or disables operator to manage the token_id token.

Transfer(from: ContractAddress, to: ContractAddress, token_id: u256) event

Emitted when token_id token is transferred from from to to.

IERC721Metadata 

use openzeppelin::token::erc721::interface::IERC721Metadata;

Interface for the optional metadata functions in EIP721.

SRC5 ID

0xabbcd595a567dce909050a1038e055daccb3c42af06f0add544fa90ee91f25

Functions

Functions

name() -> ByteArray external

Returns the NFT name.

symbol() -> ByteArray external

Returns the NFT ticker symbol.

token_uri(token_id: u256) -> ByteArray external

Returns the Uniform Resource Identifier (URI) for the token_id token. If the URI is not set for token_id, the return value will be an empty ByteArray.

ERC721Component 

use openzeppelin::token::erc721::ERC721Component;

ERC721 component implementing IERC721 and IERC721Metadata.

Implementing SRC5Component is a requirement for this component to be implemented.
See Hooks to understand how are hooks used.
Hooks
Internal functions
InternalImpl
Events
IERC721

Hooks

Hooks are functions which implementations can extend the functionality of the component source code. Every contract using ERC721Component is expected to provide an implementation of the ERC721HooksTrait. For basic token contracts, an empty implementation with no logic must be provided.

You can use openzeppelin::token::erc721::ERC721HooksEmptyImpl which is already available as part of the library for this purpose.

before_update(ref self: ContractState, to: ContractAddress, token_id: u256, auth: ContractAddress) hook

Function executed at the beginning of the _update function prior to any other logic.

after_update(ref self: ContractState, to: ContractAddress, token_id: u256, auth: ContractAddress) hook

Function executed at the end of the _update function.

Embeddable functions

balance_of(self: @ContractState, account: ContractAddress) → u256 external

See IERC721::balance_of.

owner_of(self: @ContractState, token_id: u256) → ContractAddress external

See IERC721::owner_of.

Requirements:

  • token_id exists.

safe_transfer_from(ref self: ContractState, from: ContractAddress, to: ContractAddress, token_id: u256, data: Span<felt252>) external

See IERC721::safe_transfer_from.

Requirements:

  • Caller is either approved or the token_id owner.

  • to is not the zero address.

  • from is not the zero address.

  • token_id exists.

  • to is either an account contract or supports the IERC721Receiver interface.

transfer_from(ref self: ContractState, from: ContractAddress, to: ContractAddress, token_id: u256) external

See IERC721::transfer_from.

Requirements:

  • Caller either approved or the token_id owner.

  • to is not the zero address.

  • from is not the zero address.

  • token_id exists.

approve(ref self: ContractState, to: ContractAddress, token_id: u256) external

See IERC721::approve.

Requirements:

  • The caller is either an approved operator or the token_id owner.

  • to cannot be the token owner or the zero address.

  • token_id exists.

set_approval_for_all(ref self: ContractState, operator: ContractAddress, approved: bool) external

See IERC721::set_approval_for_all.

Requirements:

  • operator is not the zero address.

get_approved(self: @ContractState, token_id: u256) -> u256 external

See IERC721::get_approved.

Requirements:

  • token_id exists.

is_approved_for_all(self: @ContractState, owner: ContractAddress, operator: ContractAddress) -> bool external

See IERC721::is_approved_for_all.

name(self: @ContractState) -> ByteArray external

See IERC721Metadata::name.

symbol(self: @ContractState) -> ByteArray external

See IERC721Metadata::symbol.

token_uri(self: @ContractState, token_id: u256) -> ByteArray external

Returns the Uniform Resource Identifier (URI) for the token_id token. If a base URI is set, the resulting URI for each token will be the concatenation of the base URI and the token ID. For example, the base URI https://token-cdn-domain/ would be returned as https://token-cdn-domain/123 for token ID 123.

If the URI is not set for token_id, the return value will be an empty ByteArray.

balanceOf(self: @ContractState, account: ContractAddress) -> u256 external

See ERC721Component::balance_of.

ownerOf(self: @ContractState, tokenId: u256) -> ContractAddress external

See ERC721Component::owner_of.

safeTransferFrom(ref self: ContractState, from: ContractAddress, to: ContractAddress, tokenId: u256, data: Span<felt252>) external

See ERC721Component::safe_transfer_from.

transferFrom(ref self: ContractState, from: ContractAddress, to: ContractAddress, tokenId: u256) external

See ERC721Component::transfer_from.

setApprovalForAll(ref self: ContractState, operator: ContractAddress, approved: bool) external

See ERC721Component::set_approval_for_all.

getApproved(self: @ContractState, tokenId: u256) -> ContractAddress external

See ERC721Component::get_approved.

isApprovedForAll(self: @ContractState, owner: ContractAddress, operator: ContractAddress) -> bool external

See ERC721Component::is_approved_for_all.

tokenURI(self: @ContractState, tokenId: u256) -> ByteArray external

See ERC721Component::token_uri.

Internal functions

initializer(ref self: ContractState, name: ByteArray, symbol: ByteArray, base_uri: ByteArray) internal

Initializes the contract by setting the token name and symbol. This should be used inside the contract’s constructor.

_owner_of(self: @ContractState, token_id: felt252) -> ContractAddress internal

Internal function that returns the owner address of token_id.

_require_owned(self: @ContractState, token_id: felt252) -> ContractAddress internal

Version of _owner_of that panics if owner is the zero address.

_exists(self: @ContractState, token_id: u256) -> bool internal

Internal function that returns whether token_id exists.

Tokens start existing when they are minted (_mint), and stop existing when they are burned (_burn).

_approve(ref self: ContractState, to: ContractAddress, token_id: u256, auth: ContractAddress) internal

Approve to to operate on token_id

The auth argument is optional. If the value passed is non-zero, then this function will check that auth is either the owner of the token, or approved to operate on all tokens held by this owner.

Emits an Approval event.

_approve_with_optional_event(ref self: ContractState, to: ContractAddress, token_id: u256, auth: ContractAddress, emit_event: bool) internal

Variant of _approve with an optional flag to enable or disable the Approval event. The event is not emitted in the context of transfers.

If auth is zero and emit_event is false, this function will not check that the token exists.

Requirements:

  • if auth is non-zero, it must be either the owner of the token or approved to operate on all of its tokens.

May emit an Approval event.

_set_approval_for_all(ref self: ContractState, owner: ContractAddress, operator: ContractAddress, approved: bool) internal

Enables or disables approval for operator to manage all of the owner assets.

Requirements:

  • operator is not the zero address.

Emits an Approval event.

_mint(ref self: ContractState, to: ContractAddress, token_id: u256) internal

Mints token_id and transfers it to to. Internal function without access restriction.

This method may lead to the loss of tokens if to is not aware of the ERC721 protocol.

Requirements:

  • to is not the zero address.

  • token_id does not exist.

Emits a Transfer event.

_transfer(ref self: ContractState, from: ContractAddress, to: ContractAddress, token_id: u256) internal

Transfers token_id from from to to.

Internal function without access restriction.

This method may lead to the loss of tokens if to is not aware of the ERC721 protocol.

Requirements:

  • to is not the zero address.

  • from is the token owner.

  • token_id exists.

Emits a Transfer event.

_burn(ref self: ContractState, token_id: u256) internal

Destroys token_id. The approval is cleared when the token is burned.

This internal function does not check if the caller is authorized to operate on the token.

Requirements:

  • token_id exists.

Emits a Transfer event.

_safe_mint(ref self: ContractState, to: ContractAddress, token_id: u256, data: Span<felt252>) internal

Mints token_id if to is either an account or IERC721Receiver.

data is additional data, it has no specified format and is forwarded in IERC721Receiver::on_erc721_received to to.

This method makes an external call to the recipient contract, which can lead to reentrancy vulnerabilities.

Requirements:

  • token_id does not exist.

  • to is either an account contract or supports the IERC721Receiver interface.

Emits a Transfer event.

_safe_transfer(ref self: ContractState, from: ContractAddress, to: ContractAddress, token_id: u256, data: Span<felt252>) internal

Transfers ownership of token_id from from if to is either an account or IERC721Receiver.

data is additional data, it has no specified format and is forwarded in IERC721Receiver::on_erc721_received to to.

This method makes an external call to the recipient contract, which can lead to reentrancy vulnerabilities.

Requirements:

  • to cannot be the zero address.

  • from must be the token owner.

  • token_id exists.

  • to is either an account contract or supports the IERC721Receiver interface.

Emits a Transfer event.

_set_base_uri(ref self: ContractState, base_uri: ByteArray) internal

Internal function that sets the base_uri.

_base_uri(self: @ContractState) -> ByteArray internal

Base URI for computing token_uri.

If set, the resulting URI for each token will be the concatenation of the base URI and the token ID. Returns an empty ByteArray if not set.

_is_authorized(self: @ContractState, owner: ContractAddress, spender: ContractAddress, token_id: u256) -> bool internal

Returns whether spender is allowed to manage owner's tokens, or token_id in particular (ignoring whether it is owned by owner).

This function assumes that owner is the actual owner of token_id and does not verify this assumption.

_check_authorized(self: @ContractState, owner: ContractAddress, spender: ContractAddress, token_id: u256) -> bool internal

Checks if spender can operate on token_id, assuming the provided owner is the actual owner.

Requirements:

  • owner cannot be the zero address.

  • spender cannot be the zero address.

  • spender must be the owner of token_id or be approved to operate on it.

This function assumes that owner is the actual owner of token_id and does not verify this assumption.

_update(ref self: ContractState, to: ContractAddress, token_id: u256, auth: ContractAddress) internal

Transfers token_id from its current owner to to, or alternatively mints (or burns) if the current owner (or to) is the zero address. Returns the owner of the token_id before the update.

The auth argument is optional. If the value passed is non-zero, then this function will check that auth is either the owner of the token, or approved to operate on the token (by the owner).

Emits a Transfer event.

This function can be extended using the ERC721HooksTrait, to add functionality before and/or after the transfer, mint, or burn.

Events

Approval(owner: ContractAddress, approved: ContractAddress, token_id: u256) event

See IERC721::Approval.

ApprovalForAll(owner: ContractAddress, operator: ContractAddress, approved: bool) event

See IERC721::ApprovalForAll.

Transfer(from: ContractAddress, to: ContractAddress, token_id: u256) event

See IERC721::Transfer.

Receiver

IERC721Receiver 

use openzeppelin::token::erc721::interface::IERC721Receiver;

Interface for contracts that support receiving safe_transfer_from transfers.

SRC5 ID

0x3a0dff5f70d80458ad14ae37bb182a728e3c8cdda0402a5daa86620bdf910bc

Functions

Functions

on_erc721_received(operator: ContractAddress, from: ContractAddress, token_id: u256, data: Span<felt252>) -> felt252 external

Whenever an IERC721 token_id token is transferred to this non-account contract via IERC721::safe_transfer_from by operator from from, this function is called.

ERC721ReceiverComponent 

use openzeppelin::token::erc721::ERC721ReceiverComponent;

ERC721Receiver component implementing IERC721Receiver.

Implementing SRC5Component is a requirement for this component to be implemented.
Embeddable Implementations
Internal Functions
InternalImpl

Embeddable functions

on_erc721_received(self: @ContractState, operator: ContractAddress, from: ContractAddress, token_id: u256, data Span<felt252>) -> felt252 external

Returns the IERC721Receiver interface ID.

onERC721Received(self: @ContractState, operator: ContractAddress, from: ContractAddress, token_id: u256, data Span<felt252>) -> felt252 external

See ERC721ReceiverComponent::on_erc721_received.

Internal functions

initializer(ref self: ContractState) internal

Registers the IERC721Receiver interface ID as supported through introspection.

Presets

ERC721Upgradeable 

use openzeppelin::presets::ERC721Upgradeable;

Upgradeable ERC721 contract leveraging ERC721Component.

Sierra class hash

0x00f56255bf8db96498c71884407f3b623f20a5d507cbb7c41deeeb65a1bf8725

Constructor
Embedded Implementations
ERC721MixinImpl
OwnableMixinImpl
External Functions

Constructor

constructor(ref self: ContractState, name: ByteArray, symbol: ByteArray, recipient: ContractAddress, token_ids: Span<u256>, base_uri: ByteArray, owner: ContractAddress) constructor

Sets the name and symbol. Mints token_ids tokens to recipient and sets the base_uri. Assigns owner as the contract owner with permissions to upgrade.

External functions

upgrade(ref self: ContractState, new_class_hash: ClassHash) external

Upgrades the contract to a new implementation given by new_class_hash.

Requirements:

  • The caller is the contract owner.

  • new_class_hash cannot be zero.

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