fillTransaction

Fills a transaction request with the necessary fields to be signed over

The function fills in missing fields like nonce, gas, gasPrice/maxFeePerGas, and returns both the raw transaction data and the filled transaction object.

Import

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

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

Usage

An example showing how to construct a public client and fill a transaction before signing.

import (
  "context"
  "log"
  "math/big"

  "github.com/ethereum/go-ethereum/common"
  "github.com/ChefBingbong/viem-go/actions/public"
  "github.com/ChefBingbong/viem-go/client"
  "github.com/ChefBingbong/viem-go/client/transport"
  "github.com/ChefBingbong/viem-go/chain/definitions"
)

ctx := context.Background()

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

senderAddr := common.HexToAddress("0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266")
recipientAddr := common.HexToAddress("0x70997970c51812dc3a010c7d01b50e0d17dc79c8")

result, err := public.FillTransaction(ctx, publicClient, public.FillTransactionParameters{
  Account: &senderAddr,
  To:      &recipientAddr,
  Value:   big.NewInt(1000000000000000000), // 1 ETH
})
if err != nil {
  log.Fatal(err)
}
log.Printf("Nonce: %d, Gas: %d", result.Transaction.Nonce, result.Transaction.Gas)

Returns

*FillTransactionReturnType

An object containing:

Raw []byte - The RLP-encoded transaction ready to be signed
Transaction *FilledTransaction - The filled transaction with all fields populated

Parameters

Configuration options accepted by this action.

Account

Type: *common.Address
Optional

The account to fill the transaction for (msg.sender).

import (
  "github.com/ethereum/go-ethereum/common"
  "github.com/ChefBingbong/viem-go/actions/public"
)

account := common.HexToAddress("0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266")
result, err := public.FillTransaction(ctx, publicClient, public.FillTransactionParameters{
  Account: &account,
  To:      &recipientAddr,
  Value:   big.NewInt(1000000000000000000),
})

To

Type: *common.Address
Optional

The recipient address.

to := common.HexToAddress("0x70997970c51812dc3a010c7d01b50e0d17dc79c8")
result, err := public.FillTransaction(ctx, publicClient, public.FillTransactionParameters{
  Account: &senderAddr,
  To:      &to,
  Value:   big.NewInt(1000000000000000000),
})

Data

Type: []byte
Optional

Transaction data.

result, err := public.FillTransaction(ctx, publicClient, public.FillTransactionParameters{
  Account: &senderAddr,
  To:      &recipientAddr,
  Data:    []byte{0xc0, 0x2a, 0xaa, 0x39},
})

Value

Type: *big.Int
Optional

The amount of wei to send.

import "math/big"

result, err := public.FillTransaction(ctx, publicClient, public.FillTransactionParameters{
  Account: &senderAddr,
  To:      &recipientAddr,
  Value:   big.NewInt(1000000000000000000), // 1 ETH
})

Nonce

Type: *uint64
Optional

The nonce for the transaction. If nil, will be filled by the RPC.

nonce := uint64(42)
result, err := public.FillTransaction(ctx, publicClient, public.FillTransactionParameters{
  Account: &senderAddr,
  To:      &recipientAddr,
  Nonce:   &nonce,
})

Gas

Type: *uint64
Optional

The gas limit. If nil, will be estimated.

gas := uint64(21000)
result, err := public.FillTransaction(ctx, publicClient, public.FillTransactionParameters{
  Account: &senderAddr,
  To:      &recipientAddr,
  Gas:     &gas,
})

GasPrice

Type: *big.Int
Optional

The gas price (legacy transactions). If nil, will be estimated.

import "math/big"

gasPrice := big.NewInt(20000000000) // 20 gwei
result, err := public.FillTransaction(ctx, publicClient, public.FillTransactionParameters{
  Account:  &senderAddr,
  To:       &recipientAddr,
  GasPrice: gasPrice,
})

MaxFeePerGas

Type: *big.Int
Optional

The max fee per gas (EIP-1559). If nil, will be estimated.

import "math/big"

maxFeePerGas := big.NewInt(20000000000) // 20 gwei
result, err := public.FillTransaction(ctx, publicClient, public.FillTransactionParameters{
  Account:       &senderAddr,
  To:            &recipientAddr,
  MaxFeePerGas:  maxFeePerGas,
})

MaxPriorityFeePerGas

Type: *big.Int
Optional

The max priority fee per gas (EIP-1559). If nil, will be estimated.

import "math/big"

maxPriorityFeePerGas := big.NewInt(2000000000) // 2 gwei
result, err := public.FillTransaction(ctx, publicClient, public.FillTransactionParameters{
  Account:             &senderAddr,
  To:                  &recipientAddr,
  MaxPriorityFeePerGas: maxPriorityFeePerGas,
})

BaseFeeMultiplier

Type: *float64
Default: 1.2 (20% buffer)
Optional

The multiplier for the base fee.

multiplier := 1.5
result, err := public.FillTransaction(ctx, publicClient, public.FillTransactionParameters{
  Account:          &senderAddr,
  To:               &recipientAddr,
  BaseFeeMultiplier: &multiplier,
})

Notes

Not all Ethereum nodes support eth_fillTransaction. This is primarily supported by Geth-based nodes. If your node doesn't support this method, you may need to manually fill the transaction using getTransactionCount, estimateGas, and getGasPrice/getMaxPriorityFeePerGas.

JSON-RPC Method

eth_fillTransaction