ERC-1155 Approve Facet

Manage ERC-1155 approvals within a diamond

Key Features

• Exposes external setApprovalForAll function for diamond routing.
• Emits ApprovalForAll event upon approval changes.
• Uses inline assembly to access diamond storage.
• Provides exportSelectors for diamond facet discovery.

Overview

This facet provides external functions for managing ERC-1155 token approvals within a diamond proxy. It integrates with diamond storage to track approval status. Developers add this facet to enable token holders to grant operators permission to transfer their ERC-1155 tokens.

Storage

ERC1155Storage

Definition

struct ERC1155Storage {
  mapping(uint256 id => mapping(address account => uint256 balance)) balanceOf;
  mapping(address account => mapping(address operator => bool)) isApprovedForAll;
}

State Variables

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

Functions

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.

---

exportSelectors

Exports the function selectors of the ERC1155ApproveFacet This function is use as a selector discovery mechanism for diamonds

function exportSelectors() external pure returns (bytes memory);

Returns:

Property	Type	Description
-	bytes	selectors The exported function selectors of the ERC1155ApproveFacet

Events

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.

Errors

Error indicating the operator address is invalid.

Signature:

error ERC1155InvalidOperator(address _operator);

Best Practices

Best Practice

• Grant approvals only to trusted operators.
• Ensure the ERC1155ApproveMod is correctly initialized before this facet is used.
• Verify that the diamond storage layout is compatible before upgrading.

Security Considerations

Security

The setApprovalForAll function allows any caller to approve or revoke an operator for their tokens. Callers must ensure they are approving legitimate operators. The facet includes an ERC1155InvalidOperator error, which is currently not used by the exposed functions, but is available for internal use or future extensions.

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Last updated:March 13, 2026