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go-web3

Ethereum Golang API

Development Environment

The requirements to develop are:

  • Golang version 1.14 or later

API

NewWeb3()

Creates a new web3 instance with http provider.

// change to your rpc provider
var rpcProviderURL = "https://rpc.flashbots.net"
web3, err := web3.NewWeb3(rpcProviderURL)
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)

pv, err := crypto.GenerateKey()
if err != nil {
    panic(err)
}
privateKey := hex.EncodeToString(crypto.FromECDSA(pv))
err := web3.Eth.SetAccount(privateKey)
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 := `[
	{
		"constant": true,
		"inputs": [],
		"name": "totalSupply",
		"outputs": [
			{
				"name": "",
				"type": "uint256"
			}
		],
		"payable": false,
		"stateMutability": "view",
		"type": "function"
	}
]`
contractAddr := "0x6B175474E89094C44Da98b954EedeAC495271d0F" // 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

Contributing

Go-Web3 welcome contributions. Please follow the guidelines when opening issues and contributing code to the repo.

Contributing

We follow the fork-and-pull Git workflow:

  1. Fork the repo on GitHub
  2. Clone it to your own machine
  3. Commit changes to your fork
  4. Push changes to your fork
  5. Submit a Pull request for review

NOTE: Be sure to merge the latest changes before making a pull request!

Pull Requests

As outlined in Keavy McMinn's article "How to write the perfect pull request", you should include:

  1. The purpose of the PR
  2. A brief overview of what you did
  3. Tag any issues that the PR relates to and close issues with a keyword
  4. What kind of feedback you're looking for (if any)
  5. Tag individuals you want feedback from (if any)

Issues

Feel free to submit issues and enhancement requests here. Please consider how to ask a good question and take the time to research your issue before asking for help.

Duplicate questions will be closed.

License

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