fuels-rs

Rust SDK for Fuel. It can be used for a variety of things, including but not limited to:

• Compiling, deploying, and testing Sway contracts;
• Launching a local Fuel network;
• Crafting and signing transactions with hand-crafted scripts or contract calls;
• Generating type-safe Rust bindings of contract methods;
• And more, fuels-rs is still in active development.

Features

• Programmatically compile Sway code
• Launch Fuel nodes
• Deploy contracts
• Interact with deployed contracts
• Type-safe Sway contracts bindings code generation
• Run Sway scripts
• CLI for common operations
• Wallet integration
• Events querying/monitoring

Using the SDK

This section describes how to use the basic functionalities of the SDK.

Instantiating a Fuel client

You can instantiate a Fuel client, pointing to a local Fuel node by using Fuel Core:

use fuel_core::service::{Config, FuelService};
use fuel_gql_client::client::FuelClient;

let server = FuelService::new_node(Config::local_node()).await.unwrap();

let client = FuelClient::from(srv.bound_address);

Alternatively, if you have a Fuel node running separately, you can pass in the SocketAddr to FuelClient::from().

It's important to setup this client, as it will be needed later when instantiating contracts. More on that on the section below.

Compiling Sway code

In order to instantiate Fuel contracts in Rust, you'll also need to compile a Sway contract. Which is done with the SDK's Contract:

let salt: [u8; 32] = rng.gen();
let salt = Salt::from(salt);

let compiled =
    Contract::compile_sway_contract("path/to/your/fuel/project", salt).unwrap();

If you're running a script instead of a contract, use the SDK's Script:

let compiled =
    Script::compile_sway_script("path/to/your/fuel/project")
        .unwrap();

Deploying a Sway contract

Once you have a Fuel node running and the compiled contract in hands, it's time to deploy the contract:

// Setup a local node
let server = FuelService::new_node(Config::local_node()).await.unwrap();
let client = FuelClient::from(srv.bound_address);

// Compile the contract
let salt: [u8; 32] = rng.gen();
let salt = Salt::from(salt);

let compiled =
    Contract::compile_sway_contract("path/to/your/fuel/project", salt).unwrap();

// Deploy the contract
let contract_id = Contract::deploy(compiled_contract, fuel_client).await.unwrap();

Alternatively, if you want to launch a local node for every deployment, which is usually useful for smaller tests where you don't want to keep state between each test, you can use Contract::launch_and_deploy():

// Build the contract
let salt: [u8; 32] = rng.gen();
let salt = Salt::from(salt);

let compiled =
    Contract::compile_sway_contract("path/to/your/fuel/project", salt).unwrap();

// Now you get both the Fuel client _and_ the contract_id back.
let (client, contract_id) = Contract::launch_and_deploy(&compiled).await.unwrap();

Generating type-safe Rust bindings

The SDK lets you transform ABI methods of a contract call, specified as JSON objects (which you can get from Forc) into Rust structs and methods that are type-checked at compile time.

For instance, a contract with two methods: initialize_counter(arg: u64) -> u64 and increment_counter(arg: u64) -> u64, with the following JSON ABI:

[
    {
        "type": "function",
        "inputs": [
            {
                "name": "arg",
                "type": "u64"
            }
        ],
        "name": "initialize_counter",
        "outputs": [
            {
                "name": "arg",
                "type": "u64"
            }
        ]
    },
    {
        "type": "function",
        "inputs": [
            {
                "name": "arg",
                "type": "u64"
            }
        ],
        "name": "increment_counter",
        "outputs": [
            {
                "name": "arg",
                "type": "u64"
            }
        ]
    }
]

Can become this (shortened for brevity's sake):

// Note that is all GENERATED code. No need to write any of that. Ever.
pub struct MyContract {
    compiled: CompiledContract,
    fuel_client: FuelClient,
}

impl MyContract {
    pub fn new(compiled: CompiledContract, fuel_client: FuelClient) -> Self {
        Self {
            compiled,
            fuel_client,
        }
    }
    #[doc = "Calls the contract\'s `initialize_counter` (0x0000000002dadd54) function"]
    pub fn initialize_counter(&self, arg: u64) -> ContractCall<u64> {
        Contract::method_hash(
            &self.fuel_client,
            &self.compiled,
            [0, 0, 0, 0, 2, 218, 221, 84],
            &[arg.into_token()],
        )
        .expect("method not found (this should never happen)")
    }
    #[doc = "Calls the contract\'s `increment_counter` (0x00000000e7f89992) function"]
    pub fn increment_counter(&self, arg: u64) -> ContractCall<u64> {
        Contract::method_hash(
            &self.fuel_client,
            &self.compiled,
            [0, 0, 0, 0, 231, 248, 153, 146],
            &[arg.into_token()],
        )
        .expect("method not found (this should never happen)")
    }
}

And, then, you're able to use to call the actual methods on the deployed contract:

//...
let contract_instance = MyContract::new(compiled, client);

let result = contract_instance
    .initialize_counter(42) // Build the ABI call
    .call() // Perform the network call
    .await
    .unwrap();

assert_eq!(42, result.unwrap());

let result = contract_instance
    .increment_counter(10)
    .call()
    .await
    .unwrap();

assert_eq!(52, result.unwrap());

To generate these bindings, all you have to do is:

use fuels_abigen_macro::abigen;

abigen!(
    MyContractName,
    "path/to/json/abi.json"
);

And this abigen! macro will expand the code with the type-safe Rust bindings. It takes 2 arguments:

1. The name of the struct that will be generated (MyContractName);
2. Either a path as string to the JSON ABI file or the JSON ABI as a multiline string directly.

The same as the example above but passing the ABI definition directly:

use fuels_abigen_macro::abigen;

abigen!(
    MyContractName,
    r#"
    [
        {
            "type": "function",
            "inputs": [
                {
                    "name": "arg",
                    "type": "u64"
                }
            ],
            "name": "initialize_counter",
            "outputs": [
                {
                    "name": "arg",
                    "type": "u64"
                }
            ]
        },
        {
            "type": "function",
            "inputs": [
                {
                    "name": "arg",
                    "type": "u64"
                }
            ],
            "name": "increment_counter",
            "outputs": [
                {
                    "name": "arg",
                    "type": "u64"
                }
            ]
        }
    ]
    "#
);

Calling a Sway script

In case you want to hand-craft a Fuel transaction with a Sway script, you can use the SDK's Script:

 let compiled =
    Script::compile_sway_script("path/to/fuel/project")
        .unwrap();

let tx = Transaction::Script {
    gas_price: 0,
    gas_limit: 1_000_000,
    maturity: 0,
    receipts_root: Default::default(),
    script: compiled.raw, // Here we pass the compiled script into the transaction
    script_data: vec![],
    inputs: vec![],
    outputs: vec![],
    witnesses: vec![vec![].into()],
    metadata: None,
};

let script = Script::new(tx);

let result = script.call(&fuel_client).await.unwrap();

More examples

You can find runnable examples under fuels-abigen-macro/tests/harness.rs and fuels-contract/tests/calls.rs.