Version: dev

Declare Contract Storage

On this page, you will learn how to define storage in your smart contract.

To learn more about how storage works in Aztec, read the concepts.

Declare storage for your contract by defining a struct and annotating it as #[storage]. This will be made available to you through the reserved storage keyword within your contract functions.

You can declare public and private state variables in your storage struct.

Example

For example, the following is the storage struct for the NFT contract:

storage_struct
#[storage]
struct Storage<Context> {
    // The symbol of the NFT
    symbol: PublicImmutable<FieldCompressedString, Context>,
    // The name of the NFT
    name: PublicImmutable<FieldCompressedString, Context>,
    // The admin of the contract
    admin: PublicMutable<AztecAddress, Context>,
    // Addresses that can mint
    minters: Map<AztecAddress, PublicMutable<bool, Context>, Context>,
    // Contains the NFTs owned by each address in private.
    private_nfts: Map<AztecAddress, PrivateSet<NFTNote, Context>, Context>,
    // A map from token ID to a boolean indicating if the NFT exists.
    nft_exists: Map<Field, PublicMutable<bool, Context>, Context>,
    // A map from token ID to the public owner of the NFT.
    public_owners: Map<Field, PublicMutable<AztecAddress, Context>, Context>,
}

^{_{Source code: noir-projects/noir-contracts/contracts/app/nft_contract/src/main.nr#L41-L61}}

info

The Context parameter is injected into storage and contract functions. It provides information about the current execution mode (e.g. private or public).

Read more about the data types available in the Storage Types page.

Example​

Example