web3

README

go-web3

Ethereum Golang API

Development Environment

The requirements to develop are:

• Golang version 1.14 or later

API

• NewWeb3()
• SetChainId(chainId int64)
• SetAccount(privateKey string) error
• GetBlockNumber()
• GetNonce(addr common.Address, blockNumber *big.Int) (uint64, error)
• NewContract(abiString string, contractAddr ...string) (*Contract, error)
• Call(methodName string, args ...interface{}) (interface{}, error)
• EncodeABI(methodName string, args ...interface{}) ([]byte, error)
• SendRawTransaction(to common.Address,amount *big.Int,gasLimit uint64,gasPrice *big.Int,data []byte) (common.Hash, error)

NewWeb3()

Creates a new web3 instance with http provider.

// change to your rpc provider
var infuraURL = "https://mainnet.infura.io/v3/7238211010344719ad14a89db874158c"
web3, err := web3.NewWeb3(infuraURL)
if err != nil {
    panic(err)
}

GetBlockNumber()

Get current block number.

blockNumber, err := web3.Eth.GetBlockNumber()
if err != nil {
    panic(err)
}
fmt.Println("Current block number: ", blockNumber)
// => Current block number:  11997285

SetChainId(chainId int64)

Setup chainId for different network.

web3.Eth.SetChainId(1)

SetAccount(privateKey string) error

Setup default account with privateKey (hex format)

err := web3.Eth.SetAccount("610ca682d9b48e079e9017bb000a503071a158941674d304efccc68d9b8756f9")
if err != nil {
    panic(err)
}

GetNonce(addr common.Address, blockNumber *big.Int) (uint64, error)

Get transaction nonce for address

nonce, err := web3.Eth.GetNonce(web3.Eth.Address(), nil)
if err != nil {
    panic(err)
}
fmt.Println("Latest nonce: ", nonce)
// => Latest nonce: 1 

NewContract(abiString string, contractAddr ...string) (*Contract, error)

Init contract api

abiString := "" // abi string
contractAddr := "" // contract address
contract, err := web3.Eth.NewContract(abiString, contractAddr )
if err != nil {
    panic(err)
}

Call(methodName string, args ...interface{}) (interface{}, error)

Contract call method

totalSupply, err := contract.Call("totalSupply")
if err != nil {
    panic(err)
}
fmt.Printf("Total supply %v\n", totalSupply)

// => Total supply  10000000000

EncodeABI(methodName string, args ...interface{}) ([]byte, error)

EncodeABI data

data, err := contract.EncodeABI("balanceOf", web3.Eth.Address())
if err != nil {
    panic(err)
}
fmt.Printf("Data %x\n", data)

// => Data 70a08231000000000000000000000000c13a163dd812ed7eb8bb9152651054eae5ee0999 

SendRawTransaction(to common.Address,amount *big.Int,gasLimit uint64,gasPrice *big.Int,data []byte) (common.Hash, error)

Send transaction

txHash, err := web3.Eth.SendRawTransaction(
    common.HexToAddress(tokenAddr),
    big.NewInt(0),
    gasLimit,
    web3.Utils.ToGWei(1),
    approveInputData,
)
if err != nil {
    panic(err)
}
fmt.Printf("Send approve tx hash %v\n", txHash)

// => Send approve tx hash  0x837136c8b6f34b519c049d1cf703d3bba47d32f6801c25d83d0113bdc0e6936a 

Examples

• Chain API
• Contract API

License

The go-web3 source code is available under the LGPL-3.0 license.

Documentation

Index

• type Web3
  • func NewWeb3(provider string) (*Web3, error)
  • func (w *Web3) Version() (string, error)

Types

type Web3

type Web3 struct {
	Eth   *eth.Eth
	Utils *utils.Utils
	// contains filtered or unexported fields
}

func NewWeb3

func NewWeb3(provider string) (*Web3, error)

func (*Web3) Version

func (w *Web3) Version() (string, error)