How to use Solana rust client to request SOL balance?

Question

I am trying to use Rust (not Typescript) to query Solana and retrieve the SOL balance of a given account.

But I can't seem to be able to do this. What I have thus far. As dependencies I have the following:

[dependencies]
borsh = "0.9.3"
solana-client = "1.14.1"
solana-sdk = "1.14.1"
solana-program = "1.14.1"

Then in code I have the following:

use solana_sdk::commitment_config::CommitmentConfig;
use solana_client::rpc_client::RpcClient;
use solana_program::pubkey::Pubkey;

#[test]
fn get_price() {
    let rpc = RpcClient::new("https://api.devnet.solana.com".to_string());
    let balance = rpc.get_account(&Pubkey::new(b"BQeizWYD2dHmQq1b6HQqwBPrLWKitnhv5K82ZnRNPL8z")).unwrap().lamports;
    dbg!(balance);
}

But this fails with thread 'get_price' panicked at 'Slice must be the same length as a Pubkey: TryFromSliceError(())'

What am I doing wrong? And how do I get the SOL balance given that I have the public key (i.e. the address) using Rust?

Answer 1

The error message Slice must be the same length as a Pubkey: TryFromSliceError(()) is a clue to what the problem is.

Solana addresses are in base58 format, while the Pubkey::new function expects &[u8]. Converting the str directly to bytes won't work. To make it work, you need to use a utility that can convert base58 into bytes array.

Solana_sdk uses the bs58 crate and it exposes this too. So to make it work, I updated your code to below:

use solana_sdk::commitment_config::CommitmentConfig;
use solana_client::rpc_client::RpcClient;
use solana_program::pubkey::Pubkey;
use solana_sdk::{bs58}; // <- bring bs58 into scope

#[test]
fn get_price() {
 let rpc = RpcClient::new("https://api.devnet.solana.com".to_string());

 // first decode the base58 string
 let decoded_addrs = &bs58::decode("4zMMC9srt5Ri5X14GAgXhaHii3GnPAEERYPJgZJDncDU")
     .into_vec().unwrap()[..];

 let balance = rpc.get_account(&Pubkey::new(decoded_addrs)).unwrap().lamports;
    dbg!(balance);
}

By the way the address BQeizWYD2dHmQq1b6HQqwBPrLWKitnhv5K82ZnRNPL8z you used in your example does not seem to exist on devnet, so I used this USDC account instead

Edit

Going through the documentation for Pubkey again, I noticed it implements the FromStr trait. Meaning the solution can be simplified by bringing use std::str::FromStr; into scope and then creating an instance of Pubkey directly from the address string. The solution will then look like this:

use solana_client::rpc_client::RpcClient;
use solana_program::pubkey::Pubkey;

use std::str::FromStr; // <- needs to be in scope

#[test]
fn get_price() {
    let rpc = RpcClient::new("https://api.devnet.solana.com".to_string());

    let balance = rpc.get_account(
        &Pubkey::from_str("4zMMC9srt5Ri5X14GAgXhaHii3GnPAEERYPJgZJDncDU").unwrap()
    ).unwrap().lamports;

    dbg!(balance);
}