How to fetch tokenURI from Polygon smart contract?

Question

I am trying to analyse different tokens in terms of the metadata they link to. I found a Polygon-based token project: https://opensea.io/assets/matic/0x50c2eae4903261b386c27c1733588e867f1a33db/10200

I wanted to check what the metadata of this token looks like and here's the problem. After checking on Polygonscan (https://polygonscan.com/address/0x50c2eae4903261b386c27c1733588e867f1a33db#code), the smart contract code needs to be decompiled. However, after decompiling, the tokenURI cannot be found. Somehow OpenSea downloads the image and displays it correctly. How can I then try to manually verify the token metadata and determine e.g. where the graphics are stored? Let's assume we are talking about this token - 10200

Answer 1

The contract returns true when querying for the ERC721 interface (EIP 165 "Standard Interface Detection").

Using the standard EIP-721 you could query the tokenUri for existing events. For example it returns https://meta.fanadise.com/0x50c2eae4903261b386c27c1733588e867f1a33db/100 for tokenId 100.

Answer 2

It is not necessary to decompile the smart contract to get the tokenURI. You can just load the contract instance in Remix IDE with the correct interface.

Here is one way how to do that:

1. Create a new workspace from OpenZeppelin ERC721 template.
2. Compile the SampleERC721 contract.
3. At the deploy & run transactions tab
   • Make sure you connected to the Polygon Mainnet
   • Select ERC721 contract
   • Set At address to 0x50c2eae4903261b386c27c1733588e867f1a33db
   • Then call the tokenURI method with needed tokenId.

The tokenURI method will return https://meta.fanadise.com/0x50c2eae4903261b386c27c1733588e867f1a33db/10200 for the tokenId 10200.