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Provider

A Provider is a fundamental object used to interact with the Massa blockchain. It provides methods for various blockchain operations, including balance retrieval, network information, signing data, and executing smart contract operations.

A Provider can be created from a KeyPair or accessed from a Wallet account. It can be used to sign transactions and interact with the blockchain.

Creating a Provider​

There are multiple ways to create a Provider, depending on your use case. Here are two common methods:

1. From a Wallet​

In a browser environment, you can create a Provider from a Wallet. This is useful for dApps that interact with user wallets.

To use the Provider from a wallet you need two things:

  • A wallet installed: It can be MassaStation, bearby or any other wallet that supports the Massa blockchain. See wallet section.

  • The wallet-provider package installed:

npm install @massalabs/wallet-provider@next
npm install @massalabs/massa-web3@next
import { getWallets } from "@massalabs/wallet-provider";

// First we get the list of wallets installed
const walletList = await getWallets();

// Then we find the wallet we want to use
const wallet = walletList.find(
  (provider) => provider.name() === "MASSASTATION"
);

if (!wallet) {
  console.log("No wallet found");
  return;
}

// We get the accounts from the wallet
const accounts = await wallet?.accounts();

if (accounts.length === 0) {
  console.log("No accounts found");
  return;
}

// We use the first account as the provider
const provider = accounts[0];

2. From a KeyPair or Environment Variable​

For backend applications or when you have direct access to private keys, you can create a Provider from a KeyPair. This method is also useful when working with environment variables for increased security.

First you will need to install the @massalabs/massa-web3 package:

npm install @massalabs/massa-web3@next

Then you can create a Provider from a KeyPair in two ways:

  • From a environment variable:
import { Account as KeyPair, Web3Provider } from "@massalabs/massa-web3";
// Will use the environment variables at `PRIVATE_KEY` to create a KeyPair
// but you can also pass the name of the env variable as a string
const keyPair = await KeyPair.fromEnv();
// Will use the KeyPair to create a Provider
const provider = Web3Provider.buildnet(keyPair);
  • From a generated KeyPair:
import { Account as KeyPair, Web3Provider } from "@massalabs/massa-web3";

// Will create a new KeyPair
const keyPair = await KeyPair.generate();
// Will use the KeyPair to create a Provider
const provider = Web3Provider.buildnet(keyPair);

Provider Methods​

A Provider offers several methods to interact with the Massa blockchain. Here are the available methods:

get address(): string

Returns the address associated with the Provider.

get accountName(): string

Returns the name of the account associated with the Provider.

get providerName(): string

Returns the name of the Provider.

balance(final: boolean): Promise<bigint>

Retrieves the balance of the account.

  • final: If true, returns the final (confirmed) balance. If false, returns the speculative (possibly unconfirmed) balance.
networkInfos(): Promise<Network>

Retrieves information about the Massa network.

sign(data: Buffer | Uint8Array | string): Promise<SignedData>

Signs the provided data.

  • data: The data to be signed.
buyRolls(amount: Mas, opts?: OperationOptions): Promise<Operation>

Buys rolls (staking units) on the Massa blockchain.

  • amount: The amount of MAS to spend on buying rolls.
  • opts: Optional operation parameters.
sellRolls(amount: Mas, opts?: OperationOptions): Promise<Operation>

Sells rolls (staking units) on the Massa blockchain.

  • amount: The number of rolls to sell.
  • opts: Optional operation parameters.
transfer(to: Address | string, amount: Mas, opts?: OperationOptions): Promise<Operation>

Transfers MAS tokens to another address.

  • to: The recipient's address.
  • amount: The amount of MAS to transfer.
  • opts: Optional operation parameters.
callSC(params: CallSCParams): Promise<Operation>

Calls a smart contract function.

  • params: Parameters for the smart contract call.
readSC(params: ReadSCParams): Promise<ReadSCData>

Reads data from a smart contract without modifying its state.

  • params: Parameters for reading from the smart contract.
deploySC(params: DeploySCParams): Promise<SmartContract>

Deploys a smart contract to the Massa blockchain.

  • params: Parameters for deploying the smart contract.
getOperationStatus(opId: string): Promise<OperationStatus>

Retrieves the status of an operation.

  • opId: The ID of the operation to check.
getEvents(filter: EventFilter): Promise<SCEvent[]>

Retrieves events based on the provided filter.

  • filter: Criteria for filtering events.