watcher-ts/packages/codegen

Code Generator

Setup

• In root of the repository:

  • Install required packages:

    yarn
    

  • Build files:

    yarn build
    

Run

• Run the following command to generate a watcher from a contract file:

  yarn codegen --input-file <input-file-path> --contract-name <contract-name> --output-folder [output-folder] --mode [eth_call | storage | all] --flatten [true | false] --kind [lazy | active]
  

  • input-file(alias: i): Input contract file path or an URL (required).
  • contract-name(alias: c): Main contract name (required).
  • output-folder(alias: o): Output folder path. (logs output using stdout if not provided).
  • mode(alias: m): Code generation mode (default: all).
  • flatten(alias: f): Flatten the input contract file (default: true).
  • kind (alias: k): Kind of watcher (default: active).

  Note: When passed an URL as input-file, it is assumed that it points to an already flattened contract file.

  Examples:

  Generate code in storage mode, lazy kind.

  yarn codegen --input-file ./test/examples/contracts/ERC721.sol --contract-name ERC721 --output-folder ../my-erc721-watcher --mode storage --kind lazy
  

  Generate code in eth_call mode using a contract provided by an URL.

  yarn codegen --input-file https://git.io/Jupci --contract-name ERC721 --output-folder ../my-erc721-watcher --mode eth_call
  

  Generate code for ERC721 in both eth_call and storage mode, active kind.

  yarn codegen --input-file ../../node_modules/@openzeppelin/contracts/token/ERC721/ERC721.sol --contract-name ERC721 --output-folder ../demo-erc721-watcher --mode all --kind active
  

  Generate code for ERC20 contract in both eth_call and storage mode, active kind:

  yarn codegen --input-file ../../node_modules/@openzeppelin/contracts/token/ERC20/ERC20.sol --contract-name ERC20 --output-folder ../demo-erc20-watcher --mode all --kind active
  

  This will create a folder called demo-erc20-watcher containing the generated code at the specified path. Follow the steps in Run Generated Watcher to setup and run the generated watcher.

Run Generated Watcher

Setup

• Run the following command to install required packages:

  yarn
  

• Create the databases configured in environments/local.toml.

• Update the state checkpoint settings in environments/local.toml.

Customize

• Indexing on an event:

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

  • While using the indexer storage methods for indexing, pass the optional arg. state as diff or checkpoint if default state is desired to be generated using the state variables being indexed else pass none.

• Generating state:

  • Edit the custom hook function createInitialCheckpoint (triggered on watch-contract, checkpoint: true) in src/hooks.ts to save an initial checkpoint IPLDBlock using the Indexer object.

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

• The existing example hooks in src/hooks.ts are for an ERC20 contract.

Run

• Run lint:

  yarn lint
  

• Run the watcher:

  yarn server
  

• If the watcher is an active watcher:

  • Run the job-runner:

    yarn job-runner
    

  • To watch a contract:

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

  • To fill a block range:

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

  • To create a checkpoint for a contract:

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

Known Issues

• Currently, node-fetch v2.6.2 is being used to fetch from URLs as v3.0.0 is an ESM-only module and ts-node transpiles to import it using require.