Connecting and running a simple query¶

use futures::TryStreamExt;
use scylla::client::session::Session;
use scylla::client::session_builder::SessionBuilder;
use std::error::Error;

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    // Create a new Session which connects to node at 127.0.0.1:9042
    // (or SCYLLA_URI if specified)
    let uri = std::env::var("SCYLLA_URI")
        .unwrap_or_else(|_| "127.0.0.1:9042".to_string());

    let session: Session = SessionBuilder::new()
        .known_node(uri)
        .build()
        .await?;

    // Create an example keyspace and table
    session
        .query_unpaged(
            "CREATE KEYSPACE IF NOT EXISTS ks WITH REPLICATION = \
            {'class' : 'NetworkTopologyStrategy', 'replication_factor' : 1}",
            &[],
        )
        .await?;

    session
        .query_unpaged(
            "CREATE TABLE IF NOT EXISTS ks.extab (a int primary key)",
            &[],
        )
        .await?;

    // Insert a value into the table
    let to_insert: i32 = 12345;
    session
        .query_unpaged("INSERT INTO ks.extab (a) VALUES(?)", (to_insert,))
        .await?;

    // Query rows from the table and print them
    let mut iter = session.query_iter("SELECT a FROM ks.extab", &[])
        .await?
        .rows_stream::<(i32,)>()?;
    while let Some(read_row) = iter.try_next().await? {
        println!("Read a value from row: {}", read_row.0);
    }

    Ok(())
}