watcher-ts/packages/erc721-watcher

erc721-watcher

To setup the stack required to run this demo, either use stack-orchestrator or do it manually.

Setup

Run the following command to install required packages:

yarn && yarn build

If the watcher is "active", first run the job-runner:

yarn job-runner

then run the watcher:

yarn server

For "lazy" watchers, you only need to run the above command.

Deploy an ERC721 token:

yarn nft:deploy

# NFT deployed to: 0xNFTAddress

Export the address of the deployed token to a shell variable for later use:

export NFT_ADDRESS="0xNFTAddress"

Run the following GQL mutation in generated watcher GraphQL endpoint http://127.0.0.1:3006/graphql

mutation {
  watchContract(
    address: "0xNFTAddress"
    kind: "ERC721"
    checkpoint: true
  )
}

TODO: settle on WC (signer/primary/main...across the docs)

Get the signer (primary/main) account address and export to a shell variable:

yarn account

export SIGNER_ADDRESS="0xSignerAddress"

Connect MetaMask to http://localhost:8545 (with chain ID 99)

Add a an account to Metamask and export the account address to a shell variable for later use:

export RECIPIENT_ADDRESS="0xRecipientAddress"

To get the current block hash at any time, run:

yarn block:latest

Run the following GQL query (eth_call) in the GraphQL playground at http://127.0.0.1:3006/graphql

query {
  name(
    blockHash: "LATEST_BLOCK_HASH"
    contractAddress: "0xNFTAddress"
  ) {
    value
    proof {
      data
    }
  }
  symbol(
    blockHash: "LATEST_BLOCK_HASH"
    contractAddress: "0xNFTAddress"
  ) {
    value
    proof {
      data
    }
  }
  balanceOf(
    blockHash: "LATEST_BLOCK_HASH"
    contractAddress: "0xNFTAddress"
    owner: "0xSignerAddress"
  ) {
    value
    proof {
      data
    }
  }
}

Run the following GQL query (storage) in generated watcher GraphQL endpoint http://127.0.0.1:3006/graphql

query {
  _name(
    blockHash: "LATEST_BLOCK_HASH"
    contractAddress: "0xNFTAddress"
  ) {
    value
    proof {
      data
    }
  }
  _symbol(
    blockHash: "LATEST_BLOCK_HASH"
    contractAddress: "0xNFTAddress"
  ) {
    value
    proof {
      data
    }
  }
  _balances(
    blockHash: "LATEST_BLOCK_HASH"
    contractAddress: "0xNFTAddress"
    key0: "0xSignerAddress"
  ) {
    value
    proof {
      data
    }
  }
}

Run the following GQL subscription in the playground:

subscription {
  onEvent {
    event {
      __typename
      ... on TransferEvent {
        from
        to
        tokenId
      },
      ... on ApprovalEvent {
        owner
        approved
        tokenId
      }
    },
    block {
      number
      hash
    }
  }
}

Mint token

yarn nft:mint --nft $NFT_ADDRESS --to $SIGNER_ADDRESS --token-id 1

• A Transfer event to 0xSignerAddress should be visible in the subscription.

• An auto-generated diff_staged State should be added with parent CID pointing to the initial checkpoint State.

• Custom property transferCount should be 1 initially.

• Run the getState query at the endpoint to get the latest State for 0xNFTAddress:

query {
  getState (
    blockHash: "EVENT_BLOCK_HASH"
    contractAddress: "0xNFTAddress"
    # kind: "checkpoint"
    # kind: "diff"
    kind: "diff_staged"
  ) {
    cid
    block {
      cid
      hash
      number
      timestamp
      parentHash
    }
    contractAddress
    data
  }
}

• diff States get created corresponding to the diff_staged blocks when their respective eth_blocks reach the pruned region.

• data contains the default state and also the custom state property transferCount that is indexed in hooks.ts file.

• Get the latest blockHash and run the following query for transferCount entity:

query {
  transferCount(
    block: {
      hash: "LATEST_BLOCK_HASH"
    }
    id: "0xNFTAddress"
  ) {
    id
    count
  }
}

Note: Contract address is assigned to the Entity ID.

With the latest blockHash, run the following query for balanceOf and ownerOf (eth_call):

query {
  fromBalanceOf: balanceOf(
    blockHash: "LATEST_BLOCK_HASH"
    contractAddress: "0xNFTAddress"
    owner: "0xSignerAddress"
  ) {
    value
    proof {
      data
    }
  }
  toBalanceOf: balanceOf(
    blockHash: "LATEST_BLOCK_HASH"
    contractAddress: "0xNFTAddress"
    owner: "0xRecipientAddress"
  ) {
    value
    proof {
      data
    }
  }
  ownerOf(
    blockHash: "LATEST_BLOCK_HASH"
    contractAddress: "0xNFTAddress"
    tokenId: 1
  ) {
    value
    proof {
      data
    }
  }
}

Transfer token

yarn nft:transfer --nft $NFT_ADDRESS --from $SIGNER_ADDRESS --to $RECIPIENT_ADDRESS --token-id 1

• An Approval event for SIGNER_ADDRESS shall be visible in the subscription at endpoint.

• A Transfer event to $RECIPIENT_ADDRESS shall be visible in the subscription at endpoint.

• An auto-generated diff_staged State should be added with parent CID pointing to the previous State.

• Custom property transferCount should be incremented after transfer. This can be checked in the getState query.

• Get the latest blockHash and replace the blockHash in the above eth_call query. The result should be different and the token should be transferred to the recipient.

• Run the getState query again at the endpoint with the event blockHash.

• Run the transferCount entity query again with the latest blockHash. The updated count should be returned.

• After the diff block has been created (can check if event block number pruned in yarn server log), create a checkpoint using CLI in packages/erc721-watcher:

yarn checkpoint create --address $NFT_ADDRESS

• Run the getState query again with the output blockHash and kind checkpoint at the endpoint.

• The latest checkpoint should have the aggregate of state diffs since the last checkpoint.

  • The State entries can be seen in pg-admin in table state.

• The state should have auto indexed data and also custom property transferCount according to code in hooks file handleEvent method.

Watch

To watch a contract:

yarn watch:contract --address <contract-address> --kind <contract-kind> --checkpoint <true | false> --starting-block [block-number]

* `address`: Address or identifier of the contract to be watched.
* `kind`: Kind of the contract.
* `checkpoint`: Turn checkpointing on (`true` | `false`).
* `starting-block`: Starting block for the contract (default: `1`).

Examples:

Watch a contract with its address and checkpointing on:

```bash
yarn watch:contract --address 0x1F78641644feB8b64642e833cE4AFE93DD6e7833 --kind ERC721 --checkpoint true
```

Watch a contract with its identifier and checkpointing on:

```bash
yarn watch:contract --address MyProtocol --kind protocol --checkpoint true
```

• To fill a block range:

  yarn fill --start-block <from-block> --end-block <to-block>
  

  • start-block: Block number to start filling from.
  • end-block: Block number till which to fill.

• To create a checkpoint for a contract:

  yarn checkpoint create --address <contract-address> --block-hash [block-hash]
  

  • address: Address or identifier of the contract for which to create a checkpoint.
  • block-hash: Hash of a block (in the pruned region) at which to create the checkpoint (default: latest canonical block hash).

• To reset the watcher to a previous block number:

  • Reset watcher:

    yarn reset watcher --block-number <previous-block-number>
    

  • Reset job-queue:

    yarn reset job-queue
    

  • Reset state:

    yarn reset state --block-number <previous-block-number>
    

  • block-number: Block number to which to reset the watcher.

• To export and import the watcher state:

  • In source watcher, export watcher state:

    yarn export-state --export-file [export-file-path] --block-number [snapshot-block-height]
    

    • export-file: Path of file to which to export the watcher data.
    • block-number: Block height at which to take snapshot for export.

  • In target watcher, run job-runner:

    yarn job-runner
    

  • Import watcher state:

    yarn import-state --import-file <import-file-path>
    

    • import-file: Path of file from which to import the watcher data.

  • Run server:

    yarn server
    

• To inspect a CID:

  yarn inspect-cid --cid <cid>
  

  • cid: CID to be inspected.

Customize

• Indexing on an event:

  • Edit the custom hook function handleEvent (triggered on an event) in hooks.ts to perform corresponding indexing using the Indexer object.

  • While using the indexer storage methods for indexing, pass diff as true if default state is desired to be generated using the state variables being indexed.

• Generating state:

  • Edit the custom hook function createInitialState (triggered if the watcher passes the start block, checkpoint: true) in hooks.ts to save an initial State using the Indexer object.

  • Edit the custom hook function createStateDiff (triggered on a block) in hooks.ts to save the state in a diff State using the Indexer object. The default state (if exists) is updated.

  • Edit the custom hook function createStateCheckpoint (triggered just before default and CLI checkpoint) in hooks.ts to save the state in a checkpoint State using the Indexer object.