ERC 1155

This document is better viewed at https://docs.openzeppelin.com/contracts/api/token/erc1155

This set of interfaces and contracts are all related to the ERC1155 Multi Token Standard.

The EIP consists of three interfaces which fulfill different roles, found here as IERC1155, IERC1155MetadataURI and IERC1155Receiver.

ERC1155 implements the mandatory IERC1155 interface, as well as the optional extension IERC1155MetadataURI, by relying on the substitution mechanism to use the same URI for all token types, dramatically reducing gas costs.

Additionally there are multiple custom extensions, including:

This core set of contracts is designed to be unopinionated, allowing developers to access the internal functions in ERC1155 (such as _mint) and expose them as external functions in the way they prefer.

Core

IERC1155 

import "@openzeppelin/contracts/token/ERC1155/IERC1155.sol";

Required interface of an ERC1155 compliant contract, as defined in the EIP.

Functions
IERC165
Events

balanceOf(address account, uint256 id) → uint256 external

Returns the value of tokens of token type id owned by account.

Requirements:

  • account cannot be the zero address.

balanceOfBatch(address[] accounts, uint256[] ids) → uint256[] external

Batched version of balanceOf.

Requirements:

  • accounts and ids must have the same length.

setApprovalForAll(address operator, bool approved) external

Grants or revokes permission to operator to transfer the caller’s tokens, according to approved,

Emits an ApprovalForAll event.

Requirements:

  • operator cannot be the caller.

isApprovedForAll(address account, address operator) → bool external

Returns true if operator is approved to transfer account's tokens.

See setApprovalForAll.

safeTransferFrom(address from, address to, uint256 id, uint256 value, bytes data) external

Transfers a value amount of tokens of type id from from to to.

This function can potentially allow a reentrancy attack when transferring tokens to an untrusted contract, when invoking {onERC1155Received} on the receiver. Ensure to follow the checks-effects-interactions pattern and consider employing reentrancy guards when interacting with untrusted contracts.

Emits a TransferSingle event.

Requirements:

  • to cannot be the zero address.

  • If the caller is not from, it must have been approved to spend from's tokens via setApprovalForAll.

  • from must have a balance of tokens of type id of at least value amount.

  • If to refers to a smart contract, it must implement IERC1155Receiver.onERC1155Received and return the acceptance magic value.

safeBatchTransferFrom(address from, address to, uint256[] ids, uint256[] values, bytes data) external

Batched version of safeTransferFrom.

This function can potentially allow a reentrancy attack when transferring tokens to an untrusted contract, when invoking {onERC1155BatchReceived} on the receiver. Ensure to follow the checks-effects-interactions pattern and consider employing reentrancy guards when interacting with untrusted contracts.

Emits either a TransferSingle or a TransferBatch event, depending on the length of the array arguments.

Requirements:

TransferSingle(address indexed operator, address indexed from, address indexed to, uint256 id, uint256 value) event

Emitted when value amount of tokens of type id are transferred from from to to by operator.

TransferBatch(address indexed operator, address indexed from, address indexed to, uint256[] ids, uint256[] values) event

Equivalent to multiple TransferSingle events, where operator, from and to are the same for all transfers.

ApprovalForAll(address indexed account, address indexed operator, bool approved) event

Emitted when account grants or revokes permission to operator to transfer their tokens, according to approved.

URI(string value, uint256 indexed id) event

Emitted when the URI for token type id changes to value, if it is a non-programmatic URI.

If an URI event was emitted for id, the standard guarantees that value will equal the value returned by IERC1155MetadataURI.uri.

IERC1155MetadataURI 

import "@openzeppelin/contracts/token/ERC1155/extensions/IERC1155MetadataURI.sol";

Interface of the optional ERC1155MetadataExtension interface, as defined in the EIP.

Functions
IERC1155
IERC165
Events
IERC1155

uri(uint256 id) → string external

Returns the URI for token type id.

If the {id} substring is present in the URI, it must be replaced by clients with the actual token type ID.

ERC1155 

import "@openzeppelin/contracts/token/ERC1155/ERC1155.sol";

Implementation of the basic standard multi-token. See https://eips.ethereum.org/EIPS/eip-1155 Originally based on code by Enjin: https://github.com/enjin/erc-1155

Functions
Events
IERC1155
Errors
IERC1155Errors

constructor(string uri_) internal

See _setURI.

supportsInterface(bytes4 interfaceId) → bool public

See IERC165.supportsInterface.

uri(uint256) → string public

See IERC1155MetadataURI.uri.

This implementation returns the same URI for all token types. It relies on the token type ID substitution mechanism defined in the EIP.

Clients calling this function must replace the {id} substring with the actual token type ID.

balanceOf(address account, uint256 id) → uint256 public

See IERC1155.balanceOf.

balanceOfBatch(address[] accounts, uint256[] ids) → uint256[] public

See IERC1155.balanceOfBatch.

Requirements:

  • accounts and ids must have the same length.

setApprovalForAll(address operator, bool approved) public

See IERC1155.setApprovalForAll.

isApprovedForAll(address account, address operator) → bool public

See IERC1155.isApprovedForAll.

safeTransferFrom(address from, address to, uint256 id, uint256 value, bytes data) public

See IERC1155.safeTransferFrom.

safeBatchTransferFrom(address from, address to, uint256[] ids, uint256[] values, bytes data) public

See IERC1155.safeBatchTransferFrom.

_update(address from, address to, uint256[] ids, uint256[] values) internal

Transfers a value amount of tokens of type id from from to to. Will mint (or burn) if from (or to) is the zero address.

Emits a TransferSingle event if the arrays contain one element, and TransferBatch otherwise.

Requirements:

The ERC-1155 acceptance check is not performed in this function. See _updateWithAcceptanceCheck instead.

_updateWithAcceptanceCheck(address from, address to, uint256[] ids, uint256[] values, bytes data) internal

Version of _update that performs the token acceptance check by calling IERC1155Receiver.onERC1155Received or IERC1155Receiver.onERC1155BatchReceived on the receiver address if it contains code (eg. is a smart contract at the moment of execution).

Overriding this function is discouraged because it poses a reentrancy risk from the receiver. So any update to the contract state after this function would break the check-effect-interaction pattern. Consider overriding _update instead.

_safeTransferFrom(address from, address to, uint256 id, uint256 value, bytes data) internal

Transfers a value tokens of token type id from from to to.

Emits a TransferSingle event.

Requirements:

  • to cannot be the zero address.

  • from must have a balance of tokens of type id of at least value amount.

  • If to refers to a smart contract, it must implement IERC1155Receiver.onERC1155Received and return the acceptance magic value.

_safeBatchTransferFrom(address from, address to, uint256[] ids, uint256[] values, bytes data) internal

Batched version of _safeTransferFrom.

Emits a TransferBatch event.

Requirements:

_setURI(string newuri) internal

Sets a new URI for all token types, by relying on the token type ID substitution mechanism defined in the EIP.

By this mechanism, any occurrence of the {id} substring in either the URI or any of the values in the JSON file at said URI will be replaced by clients with the token type ID.

For example, the https://token-cdn-domain/{id}.json URI would be interpreted by clients as https://token-cdn-domain/000000000000000000000000000000000000000000000000000000000004cce0.json for token type ID 0x4cce0.

See uri.

Because these URIs cannot be meaningfully represented by the uri event, this function emits no events.

_mint(address to, uint256 id, uint256 value, bytes data) internal

Creates a value amount of tokens of type id, and assigns them to to.

Emits a TransferSingle event.

Requirements:

_mintBatch(address to, uint256[] ids, uint256[] values, bytes data) internal

Batched version of _mint.

Emits a TransferBatch event.

Requirements:

  • ids and values must have the same length.

  • to cannot be the zero address.

  • If to refers to a smart contract, it must implement IERC1155Receiver.onERC1155BatchReceived and return the acceptance magic value.

_burn(address from, uint256 id, uint256 value) internal

Destroys a value amount of tokens of type id from from

Emits a TransferSingle event.

Requirements:

  • from cannot be the zero address.

  • from must have at least value amount of tokens of type id.

_burnBatch(address from, uint256[] ids, uint256[] values) internal

Batched version of _burn.

Emits a TransferBatch event.

Requirements:

  • from cannot be the zero address.

  • from must have at least value amount of tokens of type id.

  • ids and values must have the same length.

_setApprovalForAll(address owner, address operator, bool approved) internal

Approve operator to operate on all of owner tokens

Emits an ApprovalForAll event.

Requirements:

  • operator cannot be the zero address.

IERC1155Receiver 

import "@openzeppelin/contracts/token/ERC1155/IERC1155Receiver.sol";

Interface that must be implemented by smart contracts in order to receive ERC-1155 token transfers.

Functions
IERC165

onERC1155Received(address operator, address from, uint256 id, uint256 value, bytes data) → bytes4 external

Handles the receipt of a single ERC1155 token type. This function is called at the end of a safeTransferFrom after the balance has been updated.

To accept the transfer, this must return bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)")) (i.e. 0xf23a6e61, or its own function selector).

onERC1155BatchReceived(address operator, address from, uint256[] ids, uint256[] values, bytes data) → bytes4 external

Handles the receipt of a multiple ERC1155 token types. This function is called at the end of a safeBatchTransferFrom after the balances have been updated.

To accept the transfer(s), this must return bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)")) (i.e. 0xbc197c81, or its own function selector).

Extensions

ERC1155Pausable 

import "@openzeppelin/contracts/token/ERC1155/extensions/ERC1155Pausable.sol";

ERC1155 token with pausable token transfers, minting and burning.

Useful for scenarios such as preventing trades until the end of an evaluation period, or having an emergency switch for freezing all token transfers in the event of a large bug.

This contract does not include public pause and unpause functions. In addition to inheriting this contract, you must define both functions, invoking the Pausable._pause and Pausable._unpause internal functions, with appropriate access control, e.g. using AccessControl or Ownable. Not doing so will make the contract pause mechanism of the contract unreachable, and thus unusable.
Functions
Pausable
ERC1155
Events
Pausable
IERC1155
Errors
Pausable
IERC1155Errors

_update(address from, address to, uint256[] ids, uint256[] values) internal

See ERC1155._update.

Requirements:

  • the contract must not be paused.

ERC1155Burnable 

import "@openzeppelin/contracts/token/ERC1155/extensions/ERC1155Burnable.sol";

Extension of ERC1155 that allows token holders to destroy both their own tokens and those that they have been approved to use.

Functions
ERC1155
Events
IERC1155
Errors
IERC1155Errors

burn(address account, uint256 id, uint256 value) public

burnBatch(address account, uint256[] ids, uint256[] values) public

ERC1155Supply 

import "@openzeppelin/contracts/token/ERC1155/extensions/ERC1155Supply.sol";

Extension of ERC1155 that adds tracking of total supply per id.

Useful for scenarios where Fungible and Non-fungible tokens have to be clearly identified. Note: While a totalSupply of 1 might mean the corresponding is an NFT, there is no guarantees that no other token with the same id are not going to be minted.

This contract implies a global limit of 2**256 - 1 to the number of tokens that can be minted.
This extension should not be added in an upgrade to an already deployed contract.
Functions
ERC1155
Events
IERC1155
Errors
IERC1155Errors

totalSupply(uint256 id) → uint256 public

Total value of tokens in with a given id.

totalSupply() → uint256 public

Total value of tokens.

exists(uint256 id) → bool public

Indicates whether any token exist with a given id, or not.

_update(address from, address to, uint256[] ids, uint256[] values) internal

See ERC1155._update.

ERC1155URIStorage 

import "@openzeppelin/contracts/token/ERC1155/extensions/ERC1155URIStorage.sol";

ERC1155 token with storage based token URI management. Inspired by the ERC721URIStorage extension

Functions
ERC1155
Events
IERC1155
Errors
IERC1155Errors

uri(uint256 tokenId) → string public

See IERC1155MetadataURI.uri.

This implementation returns the concatenation of the _baseURI and the token-specific uri if the latter is set

This enables the following behaviors:

  • if _tokenURIs[tokenId] is set, then the result is the concatenation of _baseURI and _tokenURIs[tokenId] (keep in mind that _baseURI is empty per default);

  • if _tokenURIs[tokenId] is NOT set then we fallback to super.uri() which in most cases will contain ERC1155._uri;

  • if _tokenURIs[tokenId] is NOT set, and if the parents do not have a uri value set, then the result is empty.

_setURI(uint256 tokenId, string tokenURI) internal

Sets tokenURI as the tokenURI of tokenId.

_setBaseURI(string baseURI) internal

Sets baseURI as the _baseURI for all tokens

Utilities

ERC1155Holder 

import "@openzeppelin/contracts/token/ERC1155/utils/ERC1155Holder.sol";

Simple implementation of IERC1155Receiver that will allow a contract to hold ERC1155 tokens.

When inheriting this contract, you must include a way to use the received tokens, otherwise they will be stuck.
Functions

supportsInterface(bytes4 interfaceId) → bool public

See IERC165.supportsInterface.

onERC1155Received(address, address, uint256, uint256, bytes) → bytes4 public

onERC1155BatchReceived(address, address, uint256[], uint256[], bytes) → bytes4 public

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