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Provider /
Querying the Chain

Icon LinkQuerying the Chain

Once you have set up a provider, you're ready to interact with the Fuel blockchain.

We can connect to either a local or an external node:

Icon InfoCircle
  1. Running a local node
  2. Connecting to an external node

Let's look at a few examples below.

Icon LinkgetBaseAssetId

The base asset is the underlying asset used to perform any transaction on a chain. This should be fetched from a provider to then be used in transactions. 

import { Address, Provider, ScriptTransactionRequest } from 'fuels';
 
import { LOCAL_NETWORK_URL, WALLET_ADDRESS } from '../../../../env';
 
// Fetch the base asset ID using the provider
const provider = await Provider.create(LOCAL_NETWORK_URL);
const baseAssetId = provider.getBaseAssetId();
// 0x...
 
// Instantiate our recipients address
const recipientAddress = Address.fromAddressOrString(WALLET_ADDRESS);
 
// Create a transaction request
const transactionRequest = new ScriptTransactionRequest();
// Use the base asset for an operation
transactionRequest.addCoinOutput(recipientAddress, 100, baseAssetId);

Icon LinkgetCoins

Returns UTXOs coins from an account address, optionally filtered by asset ID. This method supports pagination . 

import { Provider, Wallet } from 'fuels';
 
import { LOCAL_NETWORK_URL, WALLET_PVT_KEY } from '../../../../env';
 
const provider = await Provider.create(LOCAL_NETWORK_URL);
const wallet = Wallet.fromPrivateKey(WALLET_PVT_KEY, provider);
 
const assetIdA =
  '0x0101010101010101010101010101010101010101010101010101010101010101';
const baseAssetId = provider.getBaseAssetId();
 
// Fetches up to 100 coins that have an asset ID that is equal to the base asset ID
const { coins: coinsOnlyBaseAsset } = await provider.getCoins(
  wallet.address,
  baseAssetId
);
// [
//   { amount: bn(100), assetId: baseAssetId },
//   ...
// ]
 
// Fetches up to 100 coins - irrespective of the asset ID
const { coins: coinsAnyAsset } = await provider.getCoins(wallet.address);
// [
//   { amount: bn(100), assetId: baseAssetId }
//   { amount: bn(100), assetId: assetIdA }
//   ...
// ]

This method is also implemented on the Account class and can be used without providing the address: 

import { Provider, Wallet } from 'fuels';
 
import { LOCAL_NETWORK_URL, WALLET_PVT_KEY } from '../../../../env';
 
const provider = await Provider.create(LOCAL_NETWORK_URL);
const wallet = Wallet.fromPrivateKey(WALLET_PVT_KEY, provider);
 
const baseAssetId = provider.getBaseAssetId();
 
const { coins } = await wallet.getCoins(baseAssetId);
// [
//   { amount: bn(100), assetId: baseAssetId },
//   ...
// ]

Icon LinkgetResourcesToSpend

Returns spendable resources (coins or messages) for a transaction request. It accepts an optional third parameter, excludedIds, to exclude specific UTXO IDs or coin message nonces: 

import type { CoinQuantityLike, ExcludeResourcesOption } from 'fuels';
import { Provider, ScriptTransactionRequest, Wallet } from 'fuels';
 
import { LOCAL_NETWORK_URL, WALLET_PVT_KEY } from '../../../../env';
 
const provider = await Provider.create(LOCAL_NETWORK_URL);
const wallet = Wallet.fromPrivateKey(WALLET_PVT_KEY, provider);
const assetIdA =
  '0x0101010101010101010101010101010101010101010101010101010101010101';
 
const baseAssetId = provider.getBaseAssetId();
 
const quantities: CoinQuantityLike[] = [
  { amount: 32, assetId: baseAssetId, max: 42 },
  { amount: 50, assetId: assetIdA },
];
 
const utxoId =
  '0x00000000000000000000000000000000000000000000000000000000000000010001';
const messageNonce =
  '0x381de90750098776c71544527fd253412908dec3d07ce9a7367bd1ba975908a0';
const excludedIds: ExcludeResourcesOption = {
  utxos: [utxoId],
  messages: [messageNonce],
};
 
const spendableResources = await provider.getResourcesToSpend(
  wallet.address,
  quantities,
  excludedIds
);
 
const tx = new ScriptTransactionRequest();
tx.addResources(spendableResources);

This method is also available in the Account class and can be used without providing the address: 

import type { CoinQuantityLike, ExcludeResourcesOption } from 'fuels';
import { Provider, ScriptTransactionRequest, Wallet } from 'fuels';
 
import { LOCAL_NETWORK_URL, WALLET_PVT_KEY } from '../../../../env';
 
const provider = await Provider.create(LOCAL_NETWORK_URL);
const wallet = Wallet.fromPrivateKey(WALLET_PVT_KEY, provider);
const assetIdA =
  '0x0101010101010101010101010101010101010101010101010101010101010101';
 
const baseAssetId = provider.getBaseAssetId();
 
const quantities: CoinQuantityLike[] = [
  { amount: 32, assetId: baseAssetId, max: 42 },
  { amount: 50, assetId: assetIdA },
];
 
const utxoId =
  '0x00000000000000000000000000000000000000000000000000000000000000010001';
const messageNonce =
  '0x381de90750098776c71544527fd253412908dec3d07ce9a7367bd1ba975908a0';
const excludedIds: ExcludeResourcesOption = {
  utxos: [utxoId],
  messages: [messageNonce],
};
 
const spendableResources = await wallet.getResourcesToSpend(
  quantities,
  excludedIds
);
 
const tx = new ScriptTransactionRequest();
tx.addResources(spendableResources);

Icon LinkgetBalances

Returns the sum of all UTXOs coins and unspent message coins amounts for all assets. Unlike getCoins, it only returns the total amounts, not the individual coins: 

import { Provider, Wallet } from 'fuels';
 
import { LOCAL_NETWORK_URL, WALLET_PVT_KEY } from '../../../../env';
 
const provider = await Provider.create(LOCAL_NETWORK_URL);
const wallet = Wallet.fromPrivateKey(WALLET_PVT_KEY, provider);
 
const { balances } = await provider.getBalances(wallet.address);
// [
//   { amount: bn(42), assetId: baseAssetId } // total amount of baseAssetId
//   { amount: bn(100), assetId: assetIdA } // total amount of assetIdA
// ]

This method is also available in the Account class and can be used without providing the address parameter: 

await wallet.getBalances();

Icon LinkgetBlocks

The getBlocks method returns blocks from the blockchain matching the given paginationArgs parameter, supporting pagination . The below code snippet shows how to get the last 10 blocks. 

import { Provider } from 'fuels';
 
import { LOCAL_NETWORK_URL } from '../../../../env';
 
const provider = await Provider.create(LOCAL_NETWORK_URL);
 
const blockToProduce = 3;
 
// Force-producing some blocks to make sure that blocks exist
await provider.produceBlocks(blockToProduce);
 
const { blocks } = await provider.getBlocks({
  last: blockToProduce,
});

Icon LinkgetMessageByNonce

You can use the getMessageByNonce method to retrieve a message by its nonce. 

import { launchTestNode, TestMessage } from 'fuels/test-utils';
 
const { provider } = await launchTestNode({
  nodeOptions: {
    snapshotConfig: {
      stateConfig: {
        messages: [
          new TestMessage({
            nonce:
              '0x381de90750098776c71544527fd253412908dec3d07ce9a7367bd1ba975908a0',
          }).toChainMessage(),
        ],
      },
    },
  },
});
 
const nonce =
  '0x381de90750098776c71544527fd253412908dec3d07ce9a7367bd1ba975908a0';
const message = await provider.getMessageByNonce(nonce);

Icon LinkgetMessages

You can use the getMessages method to retrieve a list of messages from the blockchain. 

import { Provider, Wallet } from 'fuels';
 
import { LOCAL_NETWORK_URL, WALLET_PVT_KEY } from '../../../../env';
 
// Instantiate a provider and wallet
const provider = await Provider.create(LOCAL_NETWORK_URL);
const wallet = Wallet.fromPrivateKey(WALLET_PVT_KEY, provider);
 
// Retrieves messages from the wallet
const { messages } = await wallet.getMessages();

Icon LinkgetMessageProof

A message proof is a cryptographic proof that a message was included in a block. You can use the getMessageProof method to retrieve a message proof for a given transaction ID and message ID.

You can retrieve a message proof by either using it's block ID: 

import type { TransactionResultMessageOutReceipt } from 'fuels';
import { sleep } from 'fuels';
import { launchTestNode } from 'fuels/test-utils';
 
using launched = await launchTestNode({
  nodeOptions: {
    args: ['--poa-instant', 'false', '--poa-interval-period', '1s'],
  },
});
 
const {
  provider,
  wallets: [sender, recipient],
} = launched;
 
// Performs a withdrawal transaction from sender to recipient, thus generating a message
const withdrawTx = await sender.withdrawToBaseLayer(
  recipient.address.toB256(),
  100
);
const result = await withdrawTx.waitForResult();
 
// Waiting for a new block to be committed (1 confirmation block)
// Retrieves the latest block
await sleep(1000);
const latestBlock = await provider.getBlock('latest');
 
// Retrieves the `nonce` via message out receipt from the initial transaction result
const { nonce } = result.receipts[0] as TransactionResultMessageOutReceipt;
 
// Retrieves the message proof for the transaction ID and nonce using the next block Id
const messageProofFromBlockId = await provider.getMessageProof(
  result.id,
  nonce,
  latestBlock?.id
);

Or by it's block height: 

import type { TransactionResultMessageOutReceipt } from 'fuels';
import { sleep } from 'fuels';
import { launchTestNode } from 'fuels/test-utils';
 
using launched = await launchTestNode({
  nodeOptions: {
    args: ['--poa-instant', 'false', '--poa-interval-period', '1s'],
  },
});
 
const {
  provider,
  wallets: [sender, recipient],
} = launched;
 
// Performs a withdrawal transaction from sender to recipient, thus generating a message
const withdrawTx = await sender.withdrawToBaseLayer(
  recipient.address.toB256(),
  100
);
const result = await withdrawTx.waitForResult();
 
// Waiting for a new block to be committed (1 confirmation block)
// Retrieves the latest block
await sleep(1000);
const latestBlock = await provider.getBlock('latest');
 
// Retrieves the `nonce` via message out receipt from the initial transaction result
const { nonce } = result.receipts[0] as TransactionResultMessageOutReceipt;
 
// Retrieves the message proof for the transaction ID and nonce using the block height
const messageProofFromBlockHeight = await provider.getMessageProof(
  result.id,
  nonce,
  undefined,
  latestBlock?.height
);

Icon LinkgetTransactions

You can use the getTransactions method to retrieve a list of transactions from the blockchain. This is limited to 30 transactions per page. 

import { Provider } from 'fuels';
 
import { LOCAL_NETWORK_URL } from '../../../../env';
 
const provider = await Provider.create(LOCAL_NETWORK_URL);
 
const { transactions } = await provider.getTransactions();