writeContract

Name: viem-go
Author: viem-go

Executes a write function on a contract

A "write" function on a Solidity contract modifies the state of the blockchain. These types of functions require gas to be executed, and hence a Transaction is needed to be broadcast in order to change the state.

Internally, encodes the function call using the ABI and delegates to sendTransaction with the ABI-encoded data.

:::warning This internally sends a transaction – it does not validate if the contract write will succeed. It is highly recommended to simulate the contract write first. :::

Import

Import the wallet actions package so you can call this action.

import "github.com/ChefBingbong/viem-go/actions/wallet"

Usage

See how to construct a wallet client and call this action.

import (
  "context"
  "log"

  "github.com/ChefBingbong/viem-go/actions/wallet"
  "github.com/ChefBingbong/viem-go/client"
  "github.com/ChefBingbong/viem-go/client/transport"
  "github.com/ChefBingbong/viem-go/chain/definitions"
)

ctx := context.Background()

walletClient, err := client.CreateWalletClient(client.WalletClientConfig{
  Chain:     definitions.Mainnet,
  Transport: transport.HTTP("https://eth.llamarpc.com"),
})
if err != nil {
  log.Fatal(err)
}
defer func() { _ = walletClient.Close() }()

hash, err := wallet.WriteContract(ctx, walletClient, wallet.WriteContractParameters{
  Address:      "0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2",
  ABI:          erc20ABI,
  FunctionName: "transfer",
  Args:         []any{toAddress, amount},
})
if err != nil {
  log.Fatal(err)
}
log.Printf("Transaction hash: %s", hash)

Returns

string

The transaction hash as a hex string.

Parameters

Configuration options accepted by this action.

Account

Control which account is used to send the contract write.

Type: Account
Optional

The account to send from. If nil, uses the client's account.

Address

Specify the contract address that will receive the write.

Type: string
Required

The contract address to call.

hash, err := wallet.WriteContract(ctx, walletClient, wallet.WriteContractParameters{
  Address:      "0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2",
  ABI:          erc20ABI,
  FunctionName: "transfer",
  Args:         []any{toAddress, amount},
})

ABI

Provide the ABI used to encode the contract call.

Type: any ([]byte, string, or *abi.ABI)
Required

The contract ABI as JSON bytes, string, or a pre-parsed *abi.ABI.

import "github.com/ChefBingbong/viem-go/abi"

// Option 1: Pre-parsed ABI
parsedABI, _ := abi.Parse([]byte(`[{"type":"function",...}]`))
hash, err := wallet.WriteContract(ctx, walletClient, wallet.WriteContractParameters{
  ABI: parsedABI,
  // ...
})

// Option 2: JSON string
hash, err := wallet.WriteContract(ctx, walletClient, wallet.WriteContractParameters{
  ABI: `[{"type":"function",...}]`,
  // ...
})

// Option 3: JSON bytes
hash, err := wallet.WriteContract(ctx, walletClient, wallet.WriteContractParameters{
  ABI: []byte(`[{"type":"function",...}]`),
  // ...
})

FunctionName

Choose which function from the ABI to call.

Type: string
Required

The name of the function to call.

hash, err := wallet.WriteContract(ctx, walletClient, wallet.WriteContractParameters{
  Address:      "0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2",
  ABI:          erc20ABI,
  FunctionName: "transfer",
  Args:         []any{toAddress, amount},
})

Args

Pass the arguments for the selected function.

Type: []any
Optional

The function arguments.

hash, err := wallet.WriteContract(ctx, walletClient, wallet.WriteContractParameters{
  Address:      "0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2",
  ABI:          erc20ABI,
  FunctionName: "transfer",
  Args:         []any{toAddress, amount},
})

Value

Optionally send ETH alongside the contract write.

Type: *big.Int
Optional

The amount of ETH to send with the transaction.

import "math/big"

hash, err := wallet.WriteContract(ctx, walletClient, wallet.WriteContractParameters{
  Address:      "0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2",
  ABI:          contractABI,
  FunctionName: "deposit",
  Value:        big.NewInt(1000000000000000000),
})

Transaction Fields

All transaction fields from sendTransaction are supported:

Chain - The target chain
AssertChainID - Whether to assert chain ID matches
DataSuffix - Data to append to the end of the calldata
Gas - Gas limit
GasPrice - Gas price (Legacy transactions)
MaxFeePerGas - Max fee per gas (EIP-1559)
MaxPriorityFeePerGas - Max priority fee per gas (EIP-1559)
Nonce - Transaction nonce
Type - Transaction type
AccessList - Access list (EIP-2930)
AuthorizationList - Authorization list (EIP-7702)
Blobs - Blobs (EIP-4844)
BlobVersionedHashes - Blob versioned hashes (EIP-4844)
MaxFeePerBlobGas - Max fee per blob gas (EIP-4844)

JSON-RPC Methods

JSON-RPC Accounts: eth_sendTransaction (with wallet_sendTransaction fallback)
Local Accounts: eth_sendRawTransaction

import ( "context" "log" "github.com/ChefBingbong/viem-go/actions/wallet" "github.com/ChefBingbong/viem-go/client" "github.com/ChefBingbong/viem-go/client/transport" "github.com/ChefBingbong/viem-go/chain/definitions" ) ctx := context.Background() walletClient, err := client.CreateWalletClient(client.WalletClientConfig{ Chain: definitions.Mainnet, Transport: transport.HTTP("https://eth.llamarpc.com"), }) if err != nil { log.Fatal(err) } defer func() { _ = walletClient.Close() }() hash, err := wallet.WriteContract(ctx, walletClient, wallet.WriteContractParameters{ Address: "0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2", ABI: erc20ABI, FunctionName: "transfer", Args: []any{toAddress, amount}, }) if err != nil { log.Fatal(err) } log.Printf("Transaction hash: %s", hash)

hash, err := wallet.WriteContract(ctx, walletClient, wallet.WriteContractParameters{ Address: "0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2", ABI: erc20ABI, FunctionName: "transfer", Args: []any{toAddress, amount}, })

import "github.com/ChefBingbong/viem-go/abi" // Option 1: Pre-parsed ABI parsedABI, _ := abi.Parse([]byte(`[{"type":"function",...}]`)) hash, err := wallet.WriteContract(ctx, walletClient, wallet.WriteContractParameters{ ABI: parsedABI, // ... }) // Option 2: JSON string hash, err := wallet.WriteContract(ctx, walletClient, wallet.WriteContractParameters{ ABI: `[{"type":"function",...}]`, // ... }) // Option 3: JSON bytes hash, err := wallet.WriteContract(ctx, walletClient, wallet.WriteContractParameters{ ABI: []byte(`[{"type":"function",...}]`), // ... })

import "math/big" hash, err := wallet.WriteContract(ctx, walletClient, wallet.WriteContractParameters{ Address: "0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2", ABI: contractABI, FunctionName: "deposit", Value: big.NewInt(1000000000000000000), })