Interacting with ink! Smart Contracts

This guide shows how to interact with ink! smart contracts using Polkadart. We’ll demonstrate using the Flipper contract example.

Prerequisites

Before getting started, you’ll need to:

1. Set up your ink! development environment - Install Rust and required dependencies
2. Create an ink! project - Create and test a basic Flipper contract
3. Build your contract - Compile the contract to Wasm
4. Run a Substrate node - Start a local development node

For more details, refer to the official ink! documentation.

Installation

Add the required dependencies to your pubspec.yaml:

dependencies:
  ink_abi: any
  ink_cli: any
  polkadart: any
  polkadart_keyring: any

Run:

dart pub get

Generate Contract Bindings

Create a file named generate_contract.dart:

import 'package:ink_cli/ink_cli.dart';

void main() {
  final fileOutput = FileOutput('generated_flipper.dart');
  final generator =
      TypeGenerator(abiFilePath: 'flipper.json', fileOutput: fileOutput);
  generator.generate();
  fileOutput.write();
}

Run this script to generate the contract bindings:

dart run generate_contract.dart

Deploy and Interact

Create a file named flipper_demo.dart:

import 'dart:io';
import 'dart:typed_data';
import 'package:polkadart/polkadart.dart';
import 'package:polkadart_keyring/polkadart_keyring.dart';
import 'generated_flipper.dart';

Future<void> main() async {
  final provider = Provider.fromUri(Uri.parse('ws://127.0.0.1:9944'));
  final alice = await KeyPair.sr25519.fromUri('//Alice');

  // Deploy contract
  final contract = Contract(
    provider: provider,
    address: Uint8List.fromList(alice.publicKey.bytes),
  );

  final result = await contract.new_contract(
    init_value: true,
    code: await File('flipper.wasm').readAsBytes(),
    keyPair: alice,
  );

  final contractAddress = result.contractAddress;
  print('Contract deployed at: $contractAddress');

  // Initialize contract instance
  final deployedContract = Contract(
    provider: provider,
    address: Uint8List.fromList(result.contractAddress),
  );

  await Future.delayed(Duration(seconds: 1));

  // Query initial value
  final initialValue = await deployedContract.get();
  print('Initial value: $initialValue');
}