ERC721A standard is an improvement on the ERC721 standard for non-fungible tokens (NFTs) on the Ethereum blockchain implemented by the Azuki team. Its primary aim is to mitigate the gas fees associated with minting tokens in batch quantities.
Considering the current state of the Ethereum network, token minting tends to be expensive due to network congestion, resulting in high gas fees for executing smart contract transactions on the blockchain. The ERC721A standard appears to address this problem, providing a potential solution detailed in this article's upcoming section.
This tutorial assumes that you:
- Understand the ERC721 contract
- Understand the ERC721 enumerable contract
If you are unfamiliar with these concepts, you can find information about ERC721 contracts here and ERC721 enumerable contracts here.
To understand ERC721A well, let us revisit the ERC721 standard main implementation.
As depicted in the above image, the ERC721 contract maps each token ID to its respective owner. This results in data storage for every individual token minted, irrespective of whether the owner previously possessed an token. The ERC721 approach involves storing each token separately, even if they are all owned by the same account. While this method has its advantages and disadvantages, for the sake of this article, we won’t delve into them. Nonetheless, we now have a general understanding of how ERC721 manages minting.
To address the challenges faced by its predecessor, ERC721A introduces an approach aimed at minimising write operations to reduce high gas fees. This is achieved by enabling an account to mint multiple NFTs within a single transaction, with only one slot in the array being filled while the rest remain empty.
In the above scenario depicted, there are two bulk minting actions performed by two different owners. Initially, Alice is responsible for minting tokens #100, #101, and #102 in a single transaction. Following this, Bob executes another minting transaction to create tokens #103 and #104.
It is not important to note, in the context of batch minting, the ERC721A contract explicitly assigns ownership only to the first token. However, for blank slot tokens, it employs an efficient search algorithm. This algorithm scans all tokens within the specified token ID range until it locates the first token containing the owner’s information.
The ERC721A contract encounters a significant drawback during token trading, notably in transferring actions, where costs tend to exceed those of batch minting. This drawback is due from the contract’s practice of only setting ownership metadata for the first token, leaving the rest unset.
As a result, when transferring a token without an explicit owner address, the contract is required to iterate through all tokenIDs until it identifies the first token with a defined owner address. It is only after this step that the contract can determine the rightful owner authorised for the transfer.
Subsequently, the contract must assign a new owner, leading to multiple adjustments in the ownership state to ensure accurate groupings. This iterative procedure results in increased gas costs and computational overhead compared to batch minting, significantly elevating the expenses associated with token trading operations.
Install the package using the following command:
npm install - save-dev erc721aIn the provided code snippet, the ERC721A library is imported, and implementation for the NFT contract is added. It is important to understand, the first argument OngamaNFT , passed into the ERC721A constructor represents the token name, while the second argument, ONFT , signifies the token symbol.
Another crucial point to highlight is the second parameter of the _mint method which is referred to asquantity determines the number of token to be minted.
In the article, we delved into the ERC721A standard, exploring its distinctions, benefits, and drawbacks compared to alternative implementations of Non-Fungible Tokens.
Additional information regarding ERC721A can be found here.
