Matching patterns to a borrowed template

Question

So, I have this piece of code that reads input.csv, inserts a column into it, and writes it tooutput.csv

extern crate csv;

use std::path::Path;

struct User {
    reference: String,
    email: String,
    firstname: String,
    lastname: String
}

fn main() {

    let mut rdr = csv::Reader::from_file("/tmp/input.csv").unwrap().has_headers(false);
    let mut wtr = csv::Writer::from_file(Path::new("/tmp/output.csv")).unwrap();

    let users = get_users();

    for record in rdr.decode() {

        let rec: Option<Vec<String>> = match record {
            Ok(rec) => Some(rec),
            Err(e) => None
        };

        match rec {
            Some(mut r) => {
                let usr = users.iter().find(|&ur| ur.reference == r[27].to_string());
                match usr {
                    Some(u) => r.insert(1, u.email),
                    None => r.insert(1, "Unknown".to_string())
                }
                wtr.write(r.iter());
            }
            None => {}
        };

    }

}

fn get_users() -> Vec<User> {
    //retrieve users
}

and this gives me an error:

error: cannot move out of borrowed content
               Some(u) => r.insert(1, u.email),
                                      ^

So, I understand that it's frustrating because u.email, because rtrying to take responsibility for it (?), But the best way to cope with this situation?

Answer 1

Here is a slightly simplified part of your code that demonstrates the problem:

struct User {
    reference: String,
    email: String
}

let users = vec![
    User { reference: "1".into(), email: "[e-mail]".into() }, 
    User { reference: "2".into(), email: "[e-mail]".into() }
];

let records: Vec<Vec<String>> = vec![
    vec!["1".into()], 
    vec!["2".into()], 
    vec!["3".into()]
];

for mut record in records {
    let usr = users.iter().find(|ur| ur.reference == record[0]);
    match usr {
        Some(u) => record.insert(1, u.email),
        None => record.insert(1, "Unknown".into())
    }
    // do whatever with record
}

usr let usr &User, User, iter() , Iterator<Item=&User>, , , find() Option<&User>. , String u: &User - . BTW, - , , ( ).

- clone():

record.insert(1, u.email.clone())

, User, , .