Derive Macro Fetch

#[derive(Fetch)]

Use this to derive the trait FetchRow for structs defined in the application logic.

Example

use odbc_api_derive::Fetch;
use odbc_api::{Connection, Error, Cursor, parameter::VarCharArray, buffers::RowVec};

#[derive(Default, Clone, Copy, Fetch)]
struct Person {
    first_name: VarCharArray<255>,
    last_name: VarCharArray<255>,
}

fn send_greetings(conn: &mut Connection) -> Result<(), Error> {
    let max_rows_in_batch = 250;
    let buffer = RowVec::<Person>::new(max_rows_in_batch);
    let mut cursor = conn.execute("SELECT first_name, last_name FROM Persons", ())?
        .expect("SELECT must yield a result set");
    let mut block_cursor = cursor.bind_buffer(buffer)?;

    while let Some(batch) = block_cursor.fetch()? {
        for person in batch.iter() {
            let first = person.first_name.as_str()
                .expect("First name must be UTF-8")
                .expect("First Name must not be NULL");
            let last = person.last_name.as_str()
                .expect("Last name must be UTF-8")
                .expect("Last Name must not be NULL");
            println!("Hello {first} {last}!")
        }
    }
    Ok(())
}