Interact with Contracts

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Read data from smart contracts and execute write operations using Para’s wallet infrastructure.

Prerequisites

You need Web3 libraries configured with Para authentication.

Ethers.js
Viem
Wagmi

Read Contract Data

import { ethers } from "ethers";

const CONTRACT_ABI = [
  "function balanceOf(address owner) view returns (uint256)",
  "function totalSupply() view returns (uint256)",
  "function name() view returns (string)",
  "function symbol() view returns (string)",
  "function decimals() view returns (uint8)"
];

async function readContractData(
  provider: ethers.Provider,
  contractAddress: string,
  userAddress: string
) {
  const contract = new ethers.Contract(
    contractAddress,
    CONTRACT_ABI,
    provider
  );

  const [balance, totalSupply, name, symbol, decimals] = await Promise.all([
    contract.balanceOf(userAddress),
    contract.totalSupply(),
    contract.name(),
    contract.symbol(),
    contract.decimals()
  ]);

  return {
    balance: ethers.formatUnits(balance, decimals),
    totalSupply: ethers.formatUnits(totalSupply, decimals),
    name,
    symbol,
    decimals
  };
}

Write Contract Data

const STAKING_ABI = [
  "function stake(uint256 amount) payable",
  "function unstake(uint256 amount)",
  "function getStakedBalance(address user) view returns (uint256)",
  "event Staked(address indexed user, uint256 amount)",
  "event Unstaked(address indexed user, uint256 amount)"
];

async function stakeTokens(
  signer: any,
  contractAddress: string,
  amount: string,
  decimals: number
) {
  const contract = new ethers.Contract(contractAddress, STAKING_ABI, signer);
  const parsedAmount = ethers.parseUnits(amount, decimals);

  const tx = await contract.stake(parsedAmount);
  await tx.wait();

  const newBalance = await contract.getStakedBalance(await signer.getAddress());

  return {
    hash: tx.hash,
    stakedAmount: ethers.formatUnits(newBalance, decimals)
  };
}

Read Contract Data

Read operations don’t need mutation helpers — use the Viem publicClient directly:

import { createPublicClient, http, formatUnits } from "viem";
import { sepolia } from "viem/chains";

const CONTRACT_ABI = [
  {
    name: "balanceOf",
    type: "function",
    stateMutability: "view",
    inputs: [{ name: "owner", type: "address" }],
    outputs: [{ type: "uint256" }],
  },
  {
    name: "totalSupply",
    type: "function",
    stateMutability: "view",
    inputs: [],
    outputs: [{ type: "uint256" }],
  },
  {
    name: "name",
    type: "function",
    stateMutability: "view",
    inputs: [],
    outputs: [{ type: "string" }],
  },
  {
    name: "symbol",
    type: "function",
    stateMutability: "view",
    inputs: [],
    outputs: [{ type: "string" }],
  },
  {
    name: "decimals",
    type: "function",
    stateMutability: "view",
    inputs: [],
    outputs: [{ type: "uint8" }],
  },
] as const;

const publicClient = createPublicClient({
  chain: sepolia,
  transport: http(),
});

async function readContractData(
  contractAddress: `0x${string}`,
  userAddress: `0x${string}`
) {
  const results = await publicClient.multicall({
    contracts: [
      {
        address: contractAddress,
        abi: CONTRACT_ABI,
        functionName: "balanceOf",
        args: [userAddress],
      },
      {
        address: contractAddress,
        abi: CONTRACT_ABI,
        functionName: "totalSupply",
      },
      {
        address: contractAddress,
        abi: CONTRACT_ABI,
        functionName: "name",
      },
      {
        address: contractAddress,
        abi: CONTRACT_ABI,
        functionName: "symbol",
      },
      {
        address: contractAddress,
        abi: CONTRACT_ABI,
        functionName: "decimals",
      },
    ],
  });

  const [balance, totalSupply, name, symbol, decimals] = results.map(
    (r) => r.result
  );

  return {
    balance: formatUnits(balance, decimals),
    totalSupply: formatUnits(totalSupply, decimals),
    name,
    symbol,
    decimals,
  };
}

Write Contract Data

import { useParaViemClient, useParaViemWriteContract } from "@getpara/react-sdk";
import { parseUnits, http } from "viem";
import { sepolia } from "viem/chains";

const STAKING_ABI = [
  {
    name: "stake",
    type: "function",
    stateMutability: "payable",
    inputs: [{ name: "amount", type: "uint256" }],
    outputs: [],
  },
] as const;

function StakeTokens({
  contractAddress,
  decimals = 18,
}: {
  contractAddress: `0x${string}`;
  decimals?: number;
}) {
  const amount = "100";

  const { viemClient } = useParaViemClient({
    walletClientConfig: { chain: sepolia, transport: http() },
  });

  const {
    writeContractAsync,
    isPending,
    data: hash,
  } = useParaViemWriteContract(viemClient);

  return (
    <div>
      <button
        onClick={() =>
          writeContract({
            address: contractAddress,
            abi: STAKING_ABI,
            functionName: "stake",
            args: [parseUnits(amount, decimals)],
          })
        }
        disabled={isPending}
      >
        {isPending ? "Staking..." : `Stake ${amount} Tokens`}
      </button>
      {hash && <p>Transaction: {hash}</p>}
    </div>
  );
}

Read Contract Data

import { useReadContracts } from "@getpara/react-sdk/wagmi";
import { formatUnits } from "viem";

const CONTRACT_ABI = [
  {
    name: "balanceOf",
    type: "function",
    stateMutability: "view",
    inputs: [{ name: "owner", type: "address" }],
    outputs: [{ type: "uint256" }]
  },
  {
    name: "totalSupply",
    type: "function",
    stateMutability: "view",
    inputs: [],
    outputs: [{ type: "uint256" }]
  },
  {
    name: "name",
    type: "function",
    stateMutability: "view",
    inputs: [],
    outputs: [{ type: "string" }]
  },
  {
    name: "symbol",
    type: "function",
    stateMutability: "view",
    inputs: [],
    outputs: [{ type: "string" }]
  },
  {
    name: "decimals",
    type: "function",
    stateMutability: "view",
    inputs: [],
    outputs: [{ type: "uint8" }]
  }
] as const;

function ContractData({
  contractAddress,
  userAddress
}: {
  contractAddress: `0x${string}`;
  userAddress: `0x${string}`;
}) {
  const { data, isPending } = useReadContracts({
    contracts: [
      {
        address: contractAddress,
        abi: CONTRACT_ABI,
        functionName: "balanceOf",
        args: [userAddress]
      },
      {
        address: contractAddress,
        abi: CONTRACT_ABI,
        functionName: "totalSupply"
      },
      {
        address: contractAddress,
        abi: CONTRACT_ABI,
        functionName: "name"
      },
      {
        address: contractAddress,
        abi: CONTRACT_ABI,
        functionName: "symbol"
      },
      {
        address: contractAddress,
        abi: CONTRACT_ABI,
        functionName: "decimals"
      }
    ]
  });

  if (isPending) return <div>Loading...</div>;

  const [balance, totalSupply, name, symbol, decimals] =
    data?.map(d => d.result) || [];

  return (
    <div>
      <p>Token: {name} ({symbol})</p>
      <p>Balance: {formatUnits(balance || 0n, decimals || 18)}</p>
      <p>Total Supply: {formatUnits(totalSupply || 0n, decimals || 18)}</p>
    </div>
  );
}

Write Contract Data

import { useWriteContract, useWaitForTransactionReceipt, useReadContract } from "@getpara/react-sdk/wagmi";
import { parseUnits, formatUnits } from "viem";

const STAKING_ABI = [
  {
    name: "stake",
    type: "function",
    stateMutability: "payable",
    inputs: [{ name: "amount", type: "uint256" }],
    outputs: []
  },
  {
    name: "getStakedBalance",
    type: "function",
    stateMutability: "view",
    inputs: [{ name: "user", type: "address" }],
    outputs: [{ type: "uint256" }]
  }
] as const;

function StakeTokens({
  contractAddress,
  userAddress,
  decimals = 18
}: {
  contractAddress: `0x${string}`;
  userAddress: `0x${string}`;
  decimals?: number;
}) {
  const amount = "100";

  const { data: hash, isPending, writeContract } = useWriteContract();

  const { isPending: isConfirming } = useWaitForTransactionReceipt({ hash });

  const { data: stakedBalance } = useReadContract({
    address: contractAddress,
    abi: STAKING_ABI,
    functionName: "getStakedBalance",
    args: [userAddress]
  });

  return (
    <div>
      <p>Staked: {formatUnits(stakedBalance || 0n, decimals)}</p>
      <button
        onClick={() => writeContract({
          address: contractAddress,
          abi: STAKING_ABI,
          functionName: "stake",
          args: [parseUnits(amount, decimals)]
        })}
        disabled={isPending || isConfirming}
      >
        {isPending ? "Staking..." : `Stake ${amount} Tokens`}
      </button>
      {hash && <p>Transaction: {hash}</p>}
    </div>
  );
}

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Troubleshooting

Interact with Contracts

Prerequisites

Read Contract Data

Write Contract Data

Read Contract Data

Write Contract Data

Read Contract Data

Write Contract Data

Next Steps

​Prerequisites

​Read Contract Data

​Write Contract Data

​Read Contract Data

​Write Contract Data

​Read Contract Data

​Write Contract Data

​Next Steps

Prerequisites

Read Contract Data

Write Contract Data

Read Contract Data

Write Contract Data

Read Contract Data

Write Contract Data

Next Steps