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);