ERC1155Facet

Manages ERC-1155 fungible and non-fungible tokens within a diamond

Key Features

• Exposes standard ERC-1155 functions via diamond routing.
• Supports both single and batch transfers and balance checks.
• Integrates with diamond storage for persistent state.
• Emits standard ERC-1155 events for off-chain tracking.

Overview

This facet implements ERC-1155 token functionality within a diamond proxy. It exposes external functions for transfers, approvals, and balance checks, routing calls through the diamond's orchestration layer. Developers add this facet to enable ERC-1155 token operations, leveraging the diamond's upgradeability and modularity.

---

Storage

ERC1155Storage

Definition

struct ERC1155Storage {
  mapping(uint256 id => mapping(address account => uint256 balance)) balanceOf;
  mapping(address account => mapping(address operator => bool)) isApprovedForAll;
  string uri;
  string baseURI;
  mapping(uint256 tokenId => string) tokenURIs;
}

State Variables

Property	Type	Description
STORAGE_POSITION	bytes32	Diamond storage slot position for this module (Value: keccak256("compose.erc1155"))

Functions

uri

Returns the URI for token type _id. If a token-specific URI is set in tokenURIs[_id], returns the concatenation of baseURI and tokenURIs[_id]. Note that baseURI is empty by default and must be set explicitly if concatenation is desired. If no token-specific URI is set, returns the default URI which applies to all token types. The default URI may contain the substring {id} which clients should replace with the actual token ID.

function uri(uint256 _id) external view returns (string memory);

Parameters:

Property	Type	Description
_id	uint256	The token ID to query.

Returns:

Property	Type	Description
-	string	The URI for the token type.

---

balanceOf

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

function balanceOf(address _account, uint256 _id) external view returns (uint256);

Parameters:

Property	Type	Description
_account	address	The address to query the balance of.
_id	uint256	The token type to query.

Returns:

Property	Type	Description
-	uint256	The balance of the token type.

---

balanceOfBatch

Batched version of balanceOf.

function balanceOfBatch(address[] calldata _accounts, uint256[] calldata _ids)
  external
  view
  returns (uint256[] memory balances);

Parameters:

Property	Type	Description
_accounts	address[]	The addresses to query the balances of.
_ids	uint256[]	The token types to query.

Returns:

Property	Type	Description
balances	uint256[]	The balances of the token types.

---

setApprovalForAll

Grants or revokes permission to operator to transfer the caller's tokens. Emits an ApprovalForAll event.

function setApprovalForAll(address _operator, bool _approved) external;

Parameters:

Property	Type	Description
_operator	address	The address to grant/revoke approval to.
_approved	bool	True to approve, false to revoke.

---

isApprovedForAll

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

function isApprovedForAll(address _account, address _operator) external view returns (bool);

Parameters:

Property	Type	Description
_account	address	The token owner.
_operator	address	The operator to query.

Returns:

Property	Type	Description
-	bool	True if the operator is approved, false otherwise.

---

safeTransferFrom

Transfers value amount of token type id from from to to. Emits a TransferSingle event.

function safeTransferFrom(address _from, address _to, uint256 _id, uint256 _value, bytes calldata _data) external;

Parameters:

Property	Type	Description
_from	address	The address to transfer from.
_to	address	The address to transfer to.
_id	uint256	The token type to transfer.
_value	uint256	The amount to transfer.
_data	bytes	Additional data with no specified format.

---

safeBatchTransferFrom

Batched version of safeTransferFrom. Emits a TransferBatch event.

function safeBatchTransferFrom(
  address _from,
  address _to,
  uint256[] calldata _ids,
  uint256[] calldata _values,
  bytes calldata _data
) external;

Parameters:

Property	Type	Description
_from	address	The address to transfer from.
_to	address	The address to transfer to.
_ids	uint256[]	The token types to transfer.
_values	uint256[]	The amounts to transfer.
_data	bytes	Additional data with no specified format.

Events

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

Signature:

event TransferSingle(
  address indexed _operator, address indexed _from, address indexed _to, uint256 _id, uint256 _value
);

Parameters:

Property	Type	Description
_operator	address	The address which initiated the transfer.
_from	address	The address which previously owned the token.
_to	address	The address which now owns the token.
_id	uint256	The token type being transferred.
_value	uint256	The amount of tokens transferred.

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

Signature:

event TransferBatch(
  address indexed _operator, address indexed _from, address indexed _to, uint256[] _ids, uint256[] _values
);

Parameters:

Property	Type	Description
_operator	address	The address which initiated the batch transfer.
_from	address	The address which previously owned the tokens.
_to	address	The address which now owns the tokens.
_ids	uint256[]	The token types being transferred.
_values	uint256[]	The amounts of tokens transferred.

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

Signature:

event ApprovalForAll(address indexed _account, address indexed _operator, bool _approved);

Parameters:

Property	Type	Description
_account	address	The token owner granting/revoking approval.
_operator	address	The address being approved/revoked.
_approved	bool	True if approval is granted, false if revoked.

Emitted when the URI for token type id changes to value.

Signature:

event URI(string _value, uint256 indexed _id);

Parameters:

Property	Type	Description
_value	string	The new URI for the token type.
_id	uint256	The token type whose URI changed.

Errors

Error indicating insufficient balance for a transfer.

Signature:

error ERC1155InsufficientBalance(address _sender, uint256 _balance, uint256 _needed, uint256 _tokenId);

Error indicating the sender address is invalid.

Signature:

error ERC1155InvalidSender(address _sender);

Error indicating the receiver address is invalid.

Signature:

error ERC1155InvalidReceiver(address _receiver);

Error indicating missing approval for an operator.

Signature:

error ERC1155MissingApprovalForAll(address _operator, address _owner);

Error indicating the approver address is invalid.

Signature:

error ERC1155InvalidApprover(address _approver);

Error indicating the operator address is invalid.

Signature:

error ERC1155InvalidOperator(address _operator);

Error indicating array length mismatch in batch operations.

Signature:

error ERC1155InvalidArrayLength(uint256 _idsLength, uint256 _valuesLength);

Best Practices

Best Practice

• Initialize the baseURI and uri mappings during diamond setup if custom URIs are required.
• Use setApprovalForAll to grant operator permissions before executing transfers on behalf of another account.
• Ensure all token IDs and values are validated before calling transfer functions to prevent unexpected behavior.

Security Considerations

Security

Follow standard Solidity security practices. Input validation is crucial for token IDs, values, sender, and receiver addresses. The safeTransferFrom and safeBatchTransferFrom functions include checks for sufficient balance and operator approval. Reentrancy is mitigated by using the checks-effects-interactions pattern.

Related Documentation

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ERC1155Mod

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Last updated:December 30, 2025