connect_contract.md

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🔌 Connect a deployed contract

Once your provider is initialized, you can connect a contract already deployed in the network.

You need 2 pieces of data:

• the address of the contract
• the ABI file of the contract (or the compiled/compressed contract file, that includes the abi)

If you don't have the abi file, the provider.getClassAt() and provider.getClassByHash() commands will recover the compressed contract file. As these methods generate a significant workload for the sequencer/node, it's recommended to store the result on your computer to be able to reuse it later without using the provider each time:

import fs from 'fs';

const compressedContract = await provider.getClassAt(addrContract);
fs.writeFileSync('./myAbi.json', json.stringify(compressedContract.abi, undefined, 2));

When possible, prefer to read the compiled contract from a local Json file, as it's much more faster, using the json.parse util provided by Starknet.js, as shown below.

Get the abi from a compiled/compressed file

import { RpcProvider, Contract, json } from 'starknet';

If you have the compiled/compressed file of the contract, use this code to recover all data, including the ABI:

const compiledContract = json.parse(
  fs.readFileSync('./compiledContracts/test.json').toString('ascii')
);

Note the json.parse util provided by Starknet.js

Connect to the contract

// initialize provider
const provider = new RpcProvider({ nodeUrl: `${myNodeUrl}` });

// initialize deployed contract
const testAddress = '0x7667469b8e93faa642573078b6bf8c790d3a6184b2a1bb39c5c923a732862e1';
const compiledTest = json.parse(fs.readFileSync('./compiledContracts/test.json').toString('ascii'));

// connect the contract
const myTestContract = new Contract(compiledTest.abi, testAddress, provider);

Typechecking and autocompletion

If you want to have typechecking and autocompletion for your contracts functions calls and catch typing errors early, you can use Abiwan!

See this guide for more details.