Smart Contract

You can refer to Precondition part to check the initiation of apiProvider, myWallet and myAccount

Invocation Transaction

High Level

const { default: Neon, api } = require("@cityofzion/neon-js");

const sb = Neon.create.scriptBuilder();
// Your contract script hash, function name and parameters
sb.emitAppCall("80de34fbe3e6488ce316b722c5455387b001df31", "name");

// Returns a hexstring
const script = sb.str;
console.log(script);

const config = {
  api: apiProvider, // Network
  url: "http://rpc.url:portNum", // RPC URL
  account: myAccount, // Your Account
  script: script, // The Smart Contract invocation script
  gas: 0, // Optional, system fee
  fees: 0, // Optional, network fee
};

// Neon API
Neon.doInvoke(config)
  .then((config) => {
    console.log("\n\n--- Response ---");
    console.log(config.response);
  })
  .catch((config) => {
    console.log(config);
  });

Low Level

const { default: Neon, tx, rpc, u } = require("@cityofzion/neon-js");

// Your contract script hash, function name and parameters
const props = {
  scriptHash: "80de34fbe3e6488ce316b722c5455387b001df31",
  operation: "name",
  args: [],
};

const script = Neon.create.script(props);

// Create transaction using Neoscan API
async function createTxByNeoScan() {
  let balance = await apiProvider.getBalance(myAccount.address);
  let transaction = new tx.InvocationTransaction({
    script: script,
    gas: 0,
  });

  transaction.addAttribute(
    tx.TxAttrUsage.Script,
    u.reverseHex(wallet.getScriptHashFromAddress(myAccount.address))
  );

  transaction.calculate(balance).sign(myAccount.privateKey);
  return transaction;
}

// Send raw transaction
const client = new rpc.RPCClient("http://rpc.url:portNum");
createTxByNeoScan().then((transaction) => {
  client
    .sendRawTransaction(transaction)
    .then((res) => {
      console.log(res);
    })
    .catch((err) => {
      console.log(err);
    });
});

Raw Level

const { default: Neon, tx, wallet, rpc, u } = require("@cityofzion/neon-js");

const props = {
  scriptHash: "80de34fbe3e6488ce316b722c5455387b001df31",
  operation: "symbol",
  args: [],
};
const script = Neon.create.script(props);

// create raw invocation transaction
let rawTransaction = new tx.InvocationTransaction({
  script: script,
  gas: 0,
});

// Build input objects and output objects.
rawTransaction.addAttribute(
  tx.TxAttrUsage.Script,
  u.reverseHex(wallet.getScriptHashFromAddress(myAccount.address))
);

// Sign transaction with sender's private key
const signature = wallet.sign(
  rawTransaction.serialize(false),
  myAccount.privateKey
);

// Add witness
rawTransaction.addWitness(
  tx.Witness.fromSignature(signature, myAccount.publicKey)
);

// Send raw transaction
const client = new rpc.RPCClient("http://rpc.url:portNum");
client
  .sendRawTransaction(rawTransaction)
  .then((res) => {
    console.log(res);
  })
  .catch((err) => {
    console.log(err);
  });

Read Invoke - No Transaction Broadcast

NOTE: This method will not send any transactions to the blockchain.

const { default: Neon, rpc } = require("@cityofzion/neon-js");

const sb = Neon.create.scriptBuilder();
sb.emitAppCall("80de34fbe3e6488ce316b722c5455387b001df31", "name");
// Returns a hexstring
const script = sb.str;

// Using RPC Query to do local invocation
rpc.Query.invokeScript(script)
  .execute("http://rpc.url:portNum")
  .then((res) => {
    console.log(res.result);
  })
  .catch((config) => {
    console.log(config);
  });

Witdraw - Receive NEO/GAS from Contract

You have to deposit some NEO/GAS to contract address in advance.

When you want to extract NEO/GAS from a smart contract, the verification trigger of the smart contract must be satisfied. It's hard to customize high level API as the verification trigger may be different from case to case.

In below example, verification trigger of the invoked smart contract will check the signature from contract owner

const {
  default: Neon,
  wallet,
  tx,
  u,
  rpc,
  CONST,
} = require("@cityofzion/neon-js");

// The unspent tx from contract
const inputObj = {
  prevHash: "95cfeed6a101babe5df8903c72952b59e239880f3be41ab2a65fb8269284765d",
  prevIndex: 0,
};

// Output to owner
const outPutObj = {
  assetId: CONST.ASSET_ID.NEO,
  value: "100",
  scriptHash: ownerAccount.scriptHash,
};

// Create raw transaction
let rawTransaction = new tx.ContractTransaction();

rawTransaction.addAttribute(
  tx.TxAttrUsage.Script,
  u.reverseHex(wallet.getScriptHashFromAddress(ownerAccount.address))
);

rawTransaction.inputs[0] = new tx.TransactionInput(inputObj);
rawTransaction.addOutput(new tx.TransactionOutput(outPutObj));

// Build invocationScript
// String, Array
const sb = Neon.create.scriptBuilder();
sb.emitPush(2);
sb.emitPush(u.str2hexstring("haha"));

let witnessObj = {
  invocationScript: sb.str,
  verificationScript: "",
};
let witness = new tx.Witness(witnessObj);
witness.scriptHash = "f3418e5385d450fe7c2126a6e2943";

rawTransaction.addWitness(witness);

// Sign transaction with sender's private key
const signature = wallet.sign(
  rawTransaction.serialize(false),
  ownerAccount.privateKey
);

// Add witness
rawTransaction.addWitness(
  tx.Witness.fromSignature(signature, ownerAccount.publicKey)
);

// Send raw transaction
const client = new rpc.RPCClient("http://rpc.url:portNum");
client
  .sendRawTransaction(rawTransaction)
  .then((res) => {
    console.log(res);
  })
  .catch((err) => {
    console.log(err);
  });