etherscan – How Does OpenSea Get Town Star ERC1155 Token Image?

erc-1155etherscanopensea

I find that contract of Town Star ERC1155 token ABI does not have uri function code

And I try to use OpenSea API to check a metadate for a random token I choose This one.

API call https://api.opensea.io/api/v1/assets?asset_contract_address=0xc36cf0cfcb5d905b8b513860db0cfe63f6cf9f5c&token_ids=122161369724616908383351484068004787912704 response as below:

{"assets":[{"id":29329471,"token_id":"122161369724616908383351484068004787912704","num_sales":56,"background_color":null,"image_url":"https://lh3.googleusercontent.com/sFXH5WPo8nACwhdrtbSBHqvondVjWUJ-pWxacKwOIPF36J_2ZIGgVSuMSi3yqJY15UpdRbPMjEYV93fYXfCNqiDyguUgf2SFQny8UCA","image_preview_url":"https://lh3.googleusercontent.com/sFXH5WPo8nACwhdrtbSBHqvondVjWUJ-pWxacKwOIPF36J_2ZIGgVSuMSi3yqJY15UpdRbPMjEYV93fYXfCNqiDyguUgf2SFQny8UCA=s250","image_thumbnail_url":"https://lh3.googleusercontent.com/sFXH5WPo8nACwhdrtbSBHqvondVjWUJ-pWxacKwOIPF36J_2ZIGgVSuMSi3yqJY15UpdRbPMjEYV93fYXfCNqiDyguUgf2SFQny8UCA=s128","image_original_url":"https://tokens.gala.games/images/sandbox-games/town-star/skins/mirandus-fabric-plant-skin.png","animation_url":null,"animation_original_url":null,"name":"Mirandus Fabric Plant Skin","description":"Changes the look of your Fabric Plant to be Mirandus themed!","external_link":null,"asset_contract":{"address":"0xc36cf0cfcb5d905b8b513860db0cfe63f6cf9f5c","asset_contract_type":"semi-fungible","created_date":"2020-06-15T19:18:12.470039","name":"Gala Games","nft_version":null,"opensea_version":null,"owner":7360995,"schema_name":"ERC1155","symbol":"","total_supply":null,"description":"From one of the founders of Zynga and some of the creative minds behind FarmVille and Words With Friends comes Town Star. Blockchain is the next evolution of gaming and has the $148B industry buzzing with excitement. It’s gaming re-imagined to benefit creators and players, alike.","external_link":"https://www.gala.games/","image_url":"https://lh3.googleusercontent.com/wp7V1K4Ezhi8yHU6LFpff-GMsjend65nRiwNz5pGAjCwk7ybznEpfUvXiIxQoOWBmeN00AGjVTRhLUqY4fee1fus=s120","default_to_fiat":false,"dev_buyer_fee_basis_points":0,"dev_seller_fee_basis_points":250,"only_proxied_transfers":false,"opensea_buyer_fee_basis_points":0,"opensea_seller_fee_basis_points":250,"buyer_fee_basis_points":0,"seller_fee_basis_points":500,"payout_address":"0xa92abb0d0dd1e8e73006fc3b6229b7bd9e0d5c61"},"permalink":"https://opensea.io/assets/0xc36cf0cfcb5d905b8b513860db0cfe63f6cf9f5c/122161369724616908383351484068004787912704","collection":{"banner_image_url":null,"chat_url":null,"created_date":"2020-07-07T04:21:17.383133","default_to_fiat":false,"description":"From one of the founders of Zynga and some of the creative minds behind FarmVille and Words With Friends comes Town Star. Blockchain is the next evolution of gaming and has the $148B industry buzzing with excitement. It’s gaming re-imagined to benefit creators and players, alike.","dev_buyer_fee_basis_points":"0","dev_seller_fee_basis_points":"250","discord_url":null,"display_data":{"card_display_style":"padded"},"external_url":"https://www.gala.games/","featured":false,"featured_image_url":null,"hidden":false,"safelist_request_status":"verified","image_url":"https://lh3.googleusercontent.com/wp7V1K4Ezhi8yHU6LFpff-GMsjend65nRiwNz5pGAjCwk7ybznEpfUvXiIxQoOWBmeN00AGjVTRhLUqY4fee1fus=s120","is_subject_to_whitelist":false,"large_image_url":"https://lh3.googleusercontent.com/wp7V1K4Ezhi8yHU6LFpff-GMsjend65nRiwNz5pGAjCwk7ybznEpfUvXiIxQoOWBmeN00AGjVTRhLUqY4fee1fus","medium_username":"GoGalaGames","name":"Town Star","only_proxied_transfers":false,"opensea_buyer_fee_basis_points":"0","opensea_seller_fee_basis_points":"250","payout_address":"0xa92abb0d0dd1e8e73006fc3b6229b7bd9e0d5c61","require_email":false,"short_description":null,"slug":"town-star","telegram_url":"https://t.me/GoGalaGames","twitter_username":"GoGalaGames","instagram_username":null,"wiki_url":null},"decimals":null,"token_metadata":"https://tokens.gala.games/sandbox-games/town-star/skins/mirandus-fabric-plant-skin.json","owner":{"user":{"username":"NullAddress"},"profile_img_url":"https://storage.googleapis.com/opensea-static/opensea-profile/1.png","address":"0x0000000000000000000000000000000000000000","config":""},"sell_orders":[{"created_date":"2022-01-11T05:48:40.269327","closing_date":"2022-07-11T05:48:15","closing_extendable":false,"expiration_time":1657518495,"listing_time":1641880003,"order_hash":"0xbf2c9369b948b835232088755d96bb66ef2edea01d13b42428dae3e242078c75","metadata":{"asset":{"id":"122161369724616908383351484068004787912704","address":"0xc36cf0cfcb5d905b8b513860db0cfe63f6cf9f5c","quantity":"1"},"schema":"ERC1155"},"exchange":"0x7be8076f4ea4a4ad08075c2508e481d6c946d12b","maker":{"user":11403466,"profile_img_url":"https://storage.googleapis.com/opensea-static/opensea-profile/26.png","address":"0x1c50bb18b4ec35103bccc10b76e9afdb289b975a","config":""},"taker":{"user":1766,"profile_img_url":"https://storage.googleapis.com/opensea-static/opensea-profile/1.png","address":"0x0000000000000000000000000000000000000000","config":""},"current_price":"3796000000.000000000000000000","current_bounty":"37960000","bounty_multiple":"0.01","maker_relayer_fee":"500","taker_relayer_fee":"0","maker_protocol_fee":"0","taker_protocol_fee":"0","maker_referrer_fee":"0","fee_recipient":{"user":3585,"profile_img_url":"https://storage.googleapis.com/opensea-static/opensea-profile/28.png","address":"0x5b3256965e7c3cf26e11fcaf296dfc8807c01073","config":"verified"},"fee_method":1,"side":1,"sale_kind":0,"target":"0xc36cf0cfcb5d905b8b513860db0cfe63f6cf9f5c","how_to_call":0,"calldata":"0xf242432a0000000000000000000000001c50bb18b4ec35103bccc10b76e9afdb289b975a00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000016700000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000000000000000a00000000000000000000000000000000000000000000000000000000000000000","replacement_pattern":"0x000000000000000000000000000000000000000000000000000000000000000000000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000","static_target":"0x0000000000000000000000000000000000000000","static_extradata":"0x","payment_token":"0x15d4c048f83bd7e37d49ea4c83a07267ec4203da","payment_token_contract":{"id":318,"symbol":"GALA","address":"0x15d4c048f83bd7e37d49ea4c83a07267ec4203da","image_url":"https://lh3.googleusercontent.com/1DcP21E8JYH0YEvBF9HD2R4LrK742KQGJyumV5kJkAxRp2wEdOcQrvsVJmUIaNJMVkFKyxSMLZRVA-sBGfCnoEDD=s120","name":"Gala","decimals":8,"eth_price":"0.000100560000000","usd_price":"0.327482000000000000"},"base_price":"3796000000","extra":"0","quantity":"1","salt":"13486021474025852519810271922175260653938170746936005350352089145218669257494","v":28,"r":"0x05539ff3074fc24fd81605aed846a6636aa4c841f7c75ac27a5b6900f2c396c2","s":"0x4dc37f0182ccf337bfca2a91d759f061dbe57353c69100f95f22f20dec821eb5","approved_on_chain":false,"cancelled":false,"finalized":false,"marked_invalid":false,"prefixed_hash":"0x0137d05a6d560944002aad2be4cfbaa91f71a38308894d032314e8e589da572d"}],"creator":{"user":null,"profile_img_url":"https://storage.googleapis.com/opensea-static/opensea-profile/17.png","address":"0x0d24de9dccd263b310b7809283786c58d1f6a667","config":""},"traits":[{"trait_type":"game","value":"Town Star","display_type":null,"max_value":null,"trait_count":239,"order":null},{"trait_type":"category","value":"Skins","display_type":null,"max_value":null,"trait_count":71,"order":null},{"trait_type":"tokenRun","value":"skins","display_type":null,"max_value":null,"trait_count":71,"order":null}],"last_sale":{"asset":{"token_id":"122161369724616908383351484068004787912704","decimals":null},"asset_bundle":null,"event_type":"successful","event_timestamp":"2022-01-13T20:21:09","auction_type":null,"total_price":"41400000000000000","payment_token":{"id":1,"symbol":"ETH","address":"0x0000000000000000000000000000000000000000","image_url":"https://storage.opensea.io/files/6f8e2979d428180222796ff4a33ab929.svg","name":"Ether","decimals":18,"eth_price":"1.000000000000000","usd_price":"3266.159999999999854000"},"transaction":{"block_hash":"0x527bc881a7162b949d7dfad15b37b852cf92cd99b613dde02afb8acdf1ab3a79","block_number":"13999276","from_account":{"user":{"username":null},"profile_img_url":"https://storage.googleapis.com/opensea-static/opensea-profile/9.png","address":"0x0ddb92119f32ae8b49b4143e404d023edbc4a5c8","config":""},"id":247299588,"timestamp":"2022-01-13T20:21:09","to_account":{"user":{"username":"OpenSea-Orders"},"profile_img_url":"https://storage.googleapis.com/opensea-static/opensea-profile/22.png","address":"0x7be8076f4ea4a4ad08075c2508e481d6c946d12b","config":"verified"},"transaction_hash":"0xb53a5518d0a0b8aabfe7f1945cfdc77f05d5f71e15a73cba683143e2cbaf1efc","transaction_index":"25"},"created_date":"2022-01-13T20:21:25.825679","quantity":"6"},"top_bid":null,"listing_date":null,"is_presale":false,"transfer_fee_payment_token":null,"transfer_fee":null}]}

And there has a key token_metadata shows https://tokens.gala.games/sandbox-games/town-star/skins/mirandus-fabric-plant-skin.json

The metadata contain image uri for token (https://tokens.gala.games/images/sandbox-games/town-star/skins/mirandus-fabric-plant-skin.png)

But… since ABI does not have uri function, how does OpenSea get that metadata uri (https://tokens.gala.games/sandbox-games/town-star/skins/mirandus-fabric-plant-skin.json)?

Best Answer

Interesting question!

Town Star token is an ERC1155 token. The tokenURI property is part of the ERC20 token specification. Hence, you won't find it in Town Star's contract. According to the docs, ERC1155's version of tokenURI is called IERC1155MetadataURI and is totally optional.

However, Town Star does contain the URI in a different place. If you look at the contract on etherscan, the create function looks like this.

function create(string calldata _uri, bool _isNF) external creatorOnly returns (uint256 _type) {

        _type = (++nonce << 128);
        if (_isNF) _type = _type | TYPE_NF_BIT;
        emit TransferSingle(msg.sender, address(0x0), address(0x0), _type, 0);


        if (bytes(_uri).length > 0) emit URI(_uri, _type);
        // the above line emits an event
  
        return _type;
    }

You can see that the create function takes in a URI in _uri parameter, but instead of storing it, it emits an event - URI. The event URI has the following definition in the contract.

event URI(string _value, uint256 indexed _id);

The topic_0 of this function is 0x6bb7ff708619ba0610cba295a58592e0451dee2622938c8755667688daf3529b. If you search the logs in etherscan with this topic_0, you'll be able to see all the events emitted, thus all the token URI. I'm adding a screenshot for reference.

Events can also be used as cheap storage in the EVM blockchains. It costs less gas than storage. The devs of Town Star have decided to use events to store the URI.

Hope this clarifies your question.

Related Solutions

[Ethereum] What does ERC1155 have to do with Opensea (and other NFT marketplaces’) “gas free minting”

Lazy minting or "Gas Free" minting can be done using both the ERC1155 standard or the ERC721 standard. There is certainly nothing preventing OpenSea and other marketplaces from using an ERC721 for lazy minting.

The reason ERC1155 is becoming the popular choice for lazy minting is because:

You have the ability to create Fungible and Non-Fungible assets
ERC1155s uses ID substitution pattern in the uri() function. This allows for easy linkage to the metadata with just the tokenId which makes it easier to lazy mint.
There is a large reduction in gas cost when using ERC1155 that increases the users experience.

Using the two basic examples below from OpenZeppelin we can see the gas savings:

Minting with an ERC721 costs 96,073
Safe Transfer for ERC721 costs 61,542
Minting with an ERC1155 costs 51,935
Safe Transfer for ERC1155 costs 53,492

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.3;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/token/ERC1155/ERC1155.sol";


contract MyERC721 is ERC721, ERC721URIStorage, Ownable {
    constructor() ERC721("MyToken", "MTK") {}

    function safeMint(address to, uint256 tokenId, string memory uri)
        public
        onlyOwner
    {
        _safeMint(to, tokenId);
        _setTokenURI(tokenId, uri);
    }

    // The following functions are overrides required by Solidity.

    function _burn(uint256 tokenId) internal override(ERC721, ERC721URIStorage) {
        super._burn(tokenId);
    }

    function tokenURI(uint256 tokenId)
        public
        view
        override(ERC721, ERC721URIStorage)
        returns (string memory)
    {
        return super.tokenURI(tokenId);
    }
}

contract MyERC1155 is ERC1155, Ownable {
    constructor() ERC1155("") {}

    function setURI(string memory newuri) public onlyOwner {
        _setURI(newuri);
    }

    function mint(address account, uint256 id, uint256 amount, bytes memory data)
        public
        onlyOwner
    {
        _mint(account, id, amount, data);
    }

    function mintBatch(address to, uint256[] memory ids, uint256[] memory amounts, bytes memory data)
        public
        onlyOwner
    {
        _mintBatch(to, ids, amounts, data);
    }
}

How can ERC1155 help with low gas fees?

ERC1155 helps with low gas fees even with basic transfer transactions because it stores data more efficiently inside the contract. If you look inside the OpenZeppelin ERC1155 contract you will see that you only need to update two mappings to transfer the token.

_balances[id][from] = fromBalance - amount;
_balances[id][to] += amount;

But for the ERC721 you have to update 3 mappings which raises the gas cost

_balances[from] -= 1;
_balances[to] += 1;
_owners[tokenId] = to;

NFT – How to Query Balance of ERC1155 Without Token ID

You can query all the NFTs from a smart contract using Moralis NFT API. Here is an example of that implementation with all the required steps: https://docs.moralis.io/web3-data-api/evm/how-to-get-all-the-nfts-from-a-collection.

Let me know if you need any help or if you have any questions!

Best Answer

Related Solutions

[Ethereum] What does ERC1155 have to do with Opensea (and other NFT marketplaces’) “gas free minting”

NFT – How to Query Balance of ERC1155 Without Token ID

Related Topic