Minimal Forwarder (Meta Transaction)

This is a translation of the Open Zeppelin Minimal Forwarder contract into ink! complying with ERC2771 standard. It allows you to create your own transaction and signature, but send them to a 3rd party who will submit them to the chain for you through this contract and they pay all the gas fees for you.

The contract is located in contracts/forwarder. Example contracts Registry/Flipper are also in the contracts/ directory. This is only here for use in testing meta-transaction.

• Forwarder - Forwarder contracts verify signers' signature and forward transaction requests to actual recipient contracts.
• MetaTxContext - Recipient contracts which want to make use of signers' information need to implements MetaTxContext trait.
• Registry - An example contract implementing MetaTxContext.
• Flipper - An example contract implementing MetaTxContext.

Setup

As a precursor, you will need the Swanky Node or any other development nodes such as Substrate Contracts Node running.

This will compile all contracts under contracts/ folder and generate typescript types and binding codes automatically.

yarn compile

In case it fails for some reason, you can also setup one by one.

1. Compile our contracts:

$ cargo contract build --manifest-path ./contracts/forwarder/Cargo.toml
$ cargo contract build --manifest-path ./contracts/flipper/Cargo.toml
$ cargo contract build --manifest-path ./contracts/registry/Cargo.toml

2. Install the npm dependencies:

$ yarn
# or
$ npm i

3. Copy contract files to the ./tests/artifacts folder:

$ cp ./target/ink/forwarder/forwarder.contract ./tests/artifacts
$ cp ./target/ink/flipper/flipper.contract ./tests/artifacts
$ cp ./target/ink/registry/registry.contract ./tests/artifacts

And metadata:

$ cp ./target/ink/forwarder/forwarder.contract ./tests/artifacts
$ cp ./target/ink/flipper/flipper.json ./tests/artifacts
$ cp ./target/ink/registry/registry.json ./tests/artifacts

4. Generate types and binding files with typechain-polkadot:

$ npx typechain-polkadot --in ./tests/artifacts --out ./tests/typedContracts

Testing

To run the test suite:

$ yarn test
# or
$ npm run test