How do I obtain a token's contract address from a transaction (programmatically)?

Question

I'm testing a simple wallet tracking app that notifies me when a wallet makes a transaction. I'm using Uniswap on the Gorli test network. The tracker is working well, but it only notifies that a transaction has occurred and the relevant transaction hash. Is there a way I can get the token details, including the CA, token name and eth spent etc just from the transaction record?

Thanks!

Answer 1

The process is straightforward if it's a direct token transfer: the token contract address is the transaction's target address. Once you have the token contract address you can query the contract for more information (such as token name, if it's available).

If the transaction uses some other contract to interact with tokens, things get more difficult. You would basically have to analyze the transaction for any external calls to other contracts, and determine if some of these called contracts are token contracts.

As for eth transfers you can just check the value field of the transaction.

Answer 2

There are more than one form of track transactions:

1. Inspecting and decoding transaction data.
2. Use of trace capabilities of your node/provider.
3. Tracing transactions and state on contracts that your transaction interact.

If you want, share what your are doing can help others to aswer more precisely your question.

Here's a link showing how to decode transaction data from UniswapV3, may help in what you are doing: How to decode uniswap v3 Router 2 transaction