Trait oracle::RowValue[−][src]

pub trait RowValue: Sized {
    fn get(row: &Row) -> Result<Self>;
}
Expand description

A trait to get a row as specified type

This is the return type of Connection::query_row_as, Connection::query_row_as_named and Row::get_as.

The trait was added to fetch column values as a tuple. The oracle crate provides implementations for a type implementing FromSql and tuples of types implementing FromSql. The number of elements in a tuple should be 1 through 50.

let conn = Connection::connect("scott", "tiger", "")?;

let sql = "select * from emp where empno = :1";

// Gets the first column value in a row.
// Values after the second column are ignored.
let empno = conn.query_row_as::<u32>(sql, &[&7369])?;

// Gets the first two column values in a row.
// Values after the third column are ignored.
let tuple_of_empno_and_ename = conn.query_row_as::<(i32, String)>(sql, &[&7499])?;

You can implement the trait for your own types. For example when you have a struct whose members are empno and ename, you can make the struct from empno and ename column values as follows:

struct Emp {
    empno: i32,
    ename: String,
}

impl RowValue for Emp {
    fn get(row: &Row) -> std::result::Result<Emp, Error> {
        Ok(Emp {
            empno: row.get("empno")?,
            ename: row.get("ename")?,
        })
    }
}

let conn = Connection::connect("scott", "tiger", "")?;
let mut stmt = conn.prepare("select * from emp", &[])?;

// Gets rows as Emp
for result in stmt.query_as::<Emp>(&[])? {
    let emp = result?;
    println!("{},{}", emp.empno, emp.ename);
}

Required methods

Implementations on Foreign Types

Implementors