Owner Data Facet

Read-only ERC-173 owner data access for diamonds

Key Features

• Exposes the contract owner via external owner() (ERC-173).
• Shares OwnerStorage at erc8042:erc173.owner with OwnerDataMod and other owner facets.
• No state-changing functions; initialization and ownership changes use other facets or the module.

Storage

State Variables

Property	Type	Description
STORAGE_POSITION	bytes32	Owner storage position within the diamond (Value: keccak256("erc173.owner"))

OwnerStorage

Definition

/** storage-location: erc8042:erc173.owner */
struct OwnerStorage {
  address owner;
}

Functions

owner

Returns the address stored in OwnerStorage.owner.

function owner() external view returns (address);

Returns:

Property	Type	Description
-	address	The current owner, or address(0) if unset or renounced.

Best Practices

• Initialize or transfer ownership with a facet that uses OwnerDataMod (for example OwnerTransferFacet) so owner() reflects the real owner before relying on this facet in production.
• Register this facet with the diamond using exportSelectors() so owner() is routed correctly after cuts or upgrades.
• Avoid defining a second facet that writes to a different owner slot; keep all owner state at erc173.owner.

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Last updated:March 24, 2026