The contract has no mention of opensea, so they must be reading it from the blockchain somehow - but I guess etherscan doesn't display these tokens in a similar way for some reason. It's all pretty new to me and I definitely don't have a super joined up understanding of it all!
To query the URI of your tokens through your contract, you need to interact with its ABI through code; alternatively, you can upload the ABI to Etherscan, which will provide a UI to query it.
You can use the URI to store base64 encoded image or svg data, and that is super cool; but will be too expensive for larger images, at which point you will link to an IPFS-hosted url.
Ah thankyou! In that course we did write a web frontend that interacts with the contract ABI to mint the NFTs, but we didn’t do the display side. I’m curious how opensea are doing it, because they can display NFTs from my contract without me ever giving them the ABI. Can you go from decompiled contract (like etherscan can generate) -> ABI maybe?
When you are implementing an NFT, you are likely implementing either the ERC 721 or the ERC 1155 interfaces; as such, certain standard functions will be available using a standard ABI call.
So OpenSea will just try to call `tokenURI`; if you have implemented the interface correctly, that will succeed, if not, OpenSea will not show a placeholder image.
The contract has no mention of opensea, so they must be reading it from the blockchain somehow - but I guess etherscan doesn't display these tokens in a similar way for some reason. It's all pretty new to me and I definitely don't have a super joined up understanding of it all!