ERC-1155 Metadata Module

Manages ERC-1155 token metadata URIs

Key Features

• Provides internal functions for ERC-1155 metadata URI management.
• Uses diamond storage (EIP-8042) for shared state persistence.
• Emits a URI event upon setting token-specific URIs.
• Functions are internal and intended for use within custom diamond facets.

Module Usage

This module provides internal functions for use in your custom facets. Import it to access shared logic and storage.

Overview

This module provides internal functions for managing ERC-1155 token metadata URIs within a diamond. It allows facets to set a base URI, token-specific URIs, and a default URI, all stored in shared diamond storage. Changes are immediately visible to all facets accessing the same storage slot.

Storage

ERC1155MetadataStorage

ERC-8042 compliant storage struct for ERC-1155 metadata. storage-location: erc8042:erc1155.metadata

Definition

struct ERC1155MetadataStorage {
  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("erc1155.metadata"))

Functions

getStorage

Returns the ERC-1155 metadata storage struct from the predefined diamond storage slot. Uses inline assembly to set the storage slot reference.

function getStorage() pure returns (ERC1155MetadataStorage storage s);

Returns:

Property	Type	Description
s	ERC1155MetadataStorage	The ERC-1155 metadata storage struct reference.

---

setBaseURI

Sets the base URI prefix for token-specific URIs. The base URI is concatenated with token-specific URIs set via setTokenURI. Does not affect the default URI used when no token-specific URI is set.

function setBaseURI(string memory _baseURI) ;

Parameters:

Property	Type	Description
_baseURI	string	The base URI string to prepend to token-specific URIs.

---

setTokenURI

Sets the token-specific URI for a given token ID. Sets tokenURIs[_tokenId] to the provided string and emits a URI event with the full computed URI. The emitted URI is the concatenation of baseURI and the token-specific URI.

function setTokenURI(uint256 _tokenId, string memory _tokenURI) ;

Parameters:

Property	Type	Description
_tokenId	uint256	The token ID to set the URI for.
_tokenURI	string	The token-specific URI string to be concatenated with baseURI.

---

setURI

Sets the default URI for all token types. This URI is used when no token-specific URI is set.

function setURI(string memory _uri) ;

Parameters:

Property	Type	Description
_uri	string	The default URI string.

Events

Title: ERC-1155 Metadata Module Provides internal metadata functionality for ERC-1155 tokens. 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.

Best Practices

Best Practice

• Ensure access control is enforced by the calling facet before invoking setBaseURI, setTokenURI, or setURI.
• Verify that the ERC1155MetadataStorage struct layout remains compatible across diamond upgrades.
• Handle the URI event emitted by setTokenURI for off-chain indexing or notifications.

Integration Notes

Shared Storage

This module interacts with diamond storage via the STORAGE_POSITION slot, identified by keccak256("erc1155.metadata"). It utilizes inline assembly to access the ERC1155MetadataStorage struct, which contains uri and baseURI fields. Any facet that reads from or writes to this storage position will observe changes made by this module immediately, adhering to the diamond storage pattern.

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Last updated:March 13, 2026