Filter for an spefic contract event

[hrndzjuanc]

Hey everyone,

I'am trying to get an event with a WebSocket on a specific contract but got nothing, can someone tell me what am i missing ?

const filter = {
        address: ' // TOKEN ADDRESS ',
        topics: [
           // This one below retrieves Transfer TX
           // ethers.utils.id("Transfer(address,address,uint256)")
            // This one does not show liquidity transactions
            ethers.utils.id("addLiquidityETH(address,uint256,uint256,uint256,address,uint256)")
        ]
    }
    this.provider.on(filter, (tx) => {
      console.log(tx.transactionHash);
    })

Any ideas ?

[ricmoo]

That should work fine. I just tried it with the Transfer event for dai using the Infura WebSocketProvider.

Make sure your contract address is correct. Also note the emitter for filter is an event, not a transaction.

[ganeshrvel]

@zemse how do we listen to the liquidity add event?

[zemse]

Depending on you're using V2 or V3, there should be an event that is emitted during a liquidity add tx, if you have that, you can simply use ethers Event API (see the provider.on(filter, ..) example, also the description of this discussion seems to have okay syntax, just the event name is wrong). Let me know if you run into any issues.

[ganeshrvel]

The below code just worked fine to capture the transfer event. But I wasn't still able to figure out the topic to capture theliquidity add event.

filter = {
    address: "dai.tokens.ethers.eth",
    topics: [
        utils.id("Transfer(address,address,uint256)")
    ]
}
provider.on(filter, (log, event) => {
    // Emitted whenever a DAI token transfer occurs
})

Any idea what might the topic for capturing the liquidity add event?

[zemse]

Are you looking at Uniswap v2 or v3? Do you have the address of the smart contract of pair/pool?

[ganeshrvel]

I was trying to use pancakeswap v2. I do have the token id and I was trying to watch for add liquidity event.

[ganeshrvel]

Same issue, were you able to you get it working?

@hrndzjuanc