".eth() method not found" when returning Http struct in a function-CodePudding

I want to establish an http connection to a Ganache test blockchain. Going through the GitHub page of the web3 crate I found this example:

#[tokio::main]
async fn main() -> web3::Result<()> {
    let _ = env_logger::try_init();
    let transport = web3::transports::Http::new("http://localhost:7545")?;
    let web3 = web3::Web3::new(transport);

    let mut accounts = web3.eth().accounts().await?;

    ...

    Ok(())
}

However I want to implement the connection setup in a function. So I tried the following:

async fn establish_web3_connection_http(url: &str) -> web3::Result<Web3<Http>>{
    let transport = web3::transports::Http::new(url)?;
    Ok(web3::Web3::new(transport))
}

...

#[tokio::main]
async fn main() -> web3::Result<()> {
    let web3_con = establish_web3_connection_http("http://localhost:7545");

    println!("Calling accounts.");
    let mut accounts = web3_con.eth().accounts().await?;
    
    Ok(())
}

This results in the following error:

Error

I am not sure why I do not return the correct value. There is not error when I don't call web3_con, so the function seems to be fine.

Is the return value somehow wrong, or how I call it?

CodePudding user response：

establish_web3_connection_http() is an async function, so it returns a future. You're trying to call .eth() on the future, when you probably want to call it on the value produced by the future. You need to await the result of this function:

let web3_con = establish_web3_connection_http("http://localhost:7545").await?;
//                                                                    ^^^^^^^

However, you don't do any awaiting in establish_web3_connection_http(), so there's no reason it needs to be async in the first place. You could just remove async from its signature instead:

fn establish_web3_connection_http(url: &str) -> web3::Result<Web3<Http>>{