Accounts

The ViewOnlyAccount trait provides a common interface to query balances.

The Account trait, in addition to the above, also provides a way to transfer assets. When performing actions in the SDK that lead to a transaction, you will typically need to provide an account that will be used to allocate resources required by the transaction, including transaction fees.

The traits are implemented by the following types:

Transferring assets

An account implements the following methods for transferring assets:

  • transfer
  • force_transfer_to_contract
  • withdraw_to_base_layer

The following examples are provided for a Wallet account. A Predicate account would work similarly, but you might need to set its predicate data before attempting to spend resources owned by it.

With wallet.transfer you can initiate a transaction to transfer an asset from your account to a target address.

        use fuels::prelude::*;

        // Setup 2 test wallets with 1 coin each.
        let num_wallets = 2;
        let coins_per_wallet = 1;
        let coin_amount = 2;

        let wallets = launch_custom_provider_and_get_wallets(
            WalletsConfig::new(Some(num_wallets), Some(coins_per_wallet), Some(coin_amount)),
            None,
            None,
        )
        .await?;

        // Transfer the base asset with amount 1 from wallet 1 to wallet 2.
        let transfer_amount = 1;
        let asset_id = Default::default();
        let _res = wallets[0]
            .transfer(
                wallets[1].address(),
                transfer_amount,
                asset_id,
                TxPolicies::default(),
            )
            .await?;

        let wallet_2_final_coins = wallets[1].get_coins(AssetId::zeroed()).await?;

        // Check that wallet 2 now has 2 coins.
        assert_eq!(wallet_2_final_coins.len(), 2);

You can transfer assets to a contract via wallet.force_transfer_to_contract.

        // Check the current balance of the contract with id 'contract_id'.
        let contract_balances = wallet
            .try_provider()?
            .get_contract_balances(&contract_id)
            .await?;
        assert!(contract_balances.is_empty());

        // Transfer an amount of 300 to the contract.
        let amount = 300;
        let asset_id = random_asset_id;
        let _res = wallet
            .force_transfer_to_contract(&contract_id, amount, asset_id, TxPolicies::default())
            .await?;

        // Check that the contract now has 1 coin.
        let contract_balances = wallet
            .try_provider()?
            .get_contract_balances(&contract_id)
            .await?;
        assert_eq!(contract_balances.len(), 1);

        let random_asset_balance = contract_balances.get(&random_asset_id).unwrap();
        assert_eq!(*random_asset_balance, 300);

For transferring assets to the base layer chain, you can use wallet.withdraw_to_base_layer.

        use std::str::FromStr;

        use fuels::prelude::*;

        let wallets = launch_custom_provider_and_get_wallets(
            WalletsConfig::new(Some(1), None, None),
            None,
            None,
        )
        .await?;
        let wallet = wallets.first().unwrap();

        let amount = 1000;
        let base_layer_address = Address::from_str(
            "0x4710162c2e3a95a6faff05139150017c9e38e5e280432d546fae345d6ce6d8fe",
        )?;
        let base_layer_address = Bech32Address::from(base_layer_address);

        // Transfer an amount of 1000 to the specified base layer address.
        let response = wallet
            .withdraw_to_base_layer(&base_layer_address, amount, TxPolicies::default())
            .await?;

        let _block_height = wallet.provider().produce_blocks(1, None).await?;

        // Retrieve a message proof from the provider.
        let proof = wallet
            .try_provider()?
            .get_message_proof(&response.tx_id, &response.nonce, None, Some(2))
            .await?;

        // Verify the amount and recipient.
        assert_eq!(proof.amount, amount);
        assert_eq!(proof.recipient, base_layer_address);

The above example creates an Address from a string and converts it to a Bech32Address. Next, it calls wallet.withdraw_to_base_layer by providing the address, the amount to be transferred, and the transaction policies. Lastly, to verify that the transfer succeeded, the relevant message proof is retrieved with provider.get_message_proof, and the amount and the recipient are verified.