description: Tutorial on how to load an initialize a smart contract with Go.

Loading a Smart Contract

These section requires knowledge of how to compile a smart contract’s ABI to a Go contract file. If you haven’t already gone through it, please read the section first.

Once you’ve compiled your smart contract’s ABI to a Go package using the abigen tool, the next step is to call the “New” method, which is in the format New<ContractName>, so in our example if you recall it’s going to be NewStore. This initializer method takes in the address of the smart contract and returns a contract instance that you can start interact with it.

  1. address := common.HexToAddress("0x147B8eb97fD247D06C4006D269c90C1908Fb5D54")
  2. instance, err := store.NewStore(address, client)
  3. if err != nil {
  4.   log.Fatal(err)
  5. }
  7. _ = instance // we'll be using this in the next section

Full code

Commands

  1. solc --abi Store.sol
  2. solc --bin Store.sol
  3. abigen --bin=Store_sol_Store.bin --abi=Store_sol_Store.abi --pkg=store --out=Store.go

Store.sol

  1. pragma solidity ^0.4.24;
  3. contract Store {
  4.   event ItemSet(bytes32 key, bytes32 value);
  6.   string public version;
  7.   mapping (bytes32 => bytes32) public items;
  9.   constructor(string _version) public {
  10.     version = _version;
  11.   }
  13.   function setItem(bytes32 key, bytes32 value) external {
  14.     items[key] = value;
  15.     emit ItemSet(key, value);
  16.   }
  17. }

contract_load.go

  1. package main
  3. import (
  4.     "fmt"
  5.     "log"
  7.     "github.com/ethereum/go-ethereum/common"
  8.     "github.com/ethereum/go-ethereum/ethclient"
  10.     store "./contracts" // for demo
  11. )
  13. func main() {
  14.     client, err := ethclient.Dial("https://rinkeby.infura.io")
  15.     if err != nil {
  16.         log.Fatal(err)
  17.     }
  19.     address := common.HexToAddress("0x147B8eb97fD247D06C4006D269c90C1908Fb5D54")
  20.     instance, err := store.NewStore(address, client)
  21.     if err != nil {
  22.         log.Fatal(err)
  23.     }
  25.     fmt.Println("contract is loaded")
  26.     _ = instance
  27. }

solc version used for these examples

  1. $ solc --version
  2. 0.4.24+commit.e67f0147.Emscripten.clang