how to search for the destination of a transaction

Question

I defined a subgraph without the contract address

  - kind: ethereum/contract
    name: Trove
    network: mainnet
    source:
      abi: Trove
      startBlock: 5
    mapping:
      kind: ethereum/events
      apiVersion: 0.0.5
      language: wasm/assemblyscript
      entities:
        - Trove
      abis:
        - name: Trove
          file: ./artifacts/contracts/trove.sol/Trove.json
      eventHandlers:
        - event: OwnershipTransferred(indexed address,indexed address)
          handler: handleOwnershipTransferred
      file: ./mappings/trove.mapping.ts

This parses without a problem.

In the handler, I'd like to get the entity from the database, based on the address of the contract that emitted it. The handler is pretty concise:

export function handleOwnershipTransferred(event: OwnershipTransferred): void {
  let id: string = Address.fromString("0x0").toHex();
  if(event.transaction.to) {
    id = event.transaction.to.toHex();
  }
  let trove = Trove.load(id);
  if (trove == null) {
    return;
  }
  trove.owner = event.params.newOwner.toHex();
  trove.save();
}

the compiler throws an error, saying:

Compile subgraphERROR TS2322: Type '~lib/@graphprotocol/graph-ts/common/numbers/Address | null' is not assignable to type '~lib/@graphprotocol/graph-ts/common/collections/ByteArray'.

     id = event.transaction.to.toHex();

In order to check my syntax I replaced the to with from like so

export function handleOwnershipTransferred(event: OwnershipTransferred): void {
  let id: string = Address.fromString("0x0").toHex();
  if(event.transaction.from) {
    id = event.transaction.from.toHex();
  }
  let trove = Trove.load(id);
  if (trove == null) {
    return;
  }
  trove.owner = event.params.newOwner.toHex();
  trove.save();
}

and this version compiles like a charm

Answer 1

for me it looks like types error, you can try directly cast the type to Address.

Code will be

import { Address } from "@graphprotocol/graph-ts";

export function handleOwnershipTransferred(event: OwnershipTransferred): void {
  const id = (event.transaction.to as Address).toHex();
  let trove = Trove.load(id);
  if (trove == null) {
    return;
  }
  trove.owner = event.params.newOwner.toHex();
  trove.save();
}

Answer 2

the version that compiles is:

  let to: Address | null = event.transaction.to;
  if(to) {
    const id: string = to.toHex();
    let trove = Trove.load(id);
    if (trove == null) {
      return;
    }
    trove.owner = event.params.newOwner.toHex();
    trove.save();
  }