Trait odbc_api::buffers::Item

source · 
pub trait Item: Sized + Copy {
    fn buffer_desc(nullable: bool) -> BufferDesc;
    fn as_slice(variant: AnySlice<'_>) -> Option<&[Self]>;
    fn as_nullable_slice(
        variant: AnySlice<'_>
    ) -> Option<NullableSlice<'_, Self>>;
    fn as_slice_mut(variant: AnySliceMut<'_>) -> Option<&mut [Self]>;
    fn as_nullable_slice_mut(
        variant: AnySliceMut<'_>
    ) -> Option<NullableSliceMut<'_, Self>>;
}
Expand description

Can either be extracted as a slice or a NullableSlice from an AnySlice. This allows the user to avoid matching on all possibile variants of an AnySlice in case the buffered type is known at compile time.

Usually used in generic code. E.g.:

use odbc_api::{Connection, buffers::Item};

fn insert_tuple2_vec<A: Item, B: Item>(
    conn: &Connection<'_>,
    insert_sql: &str,
    source: &[(A, B)],
) {
    let mut prepared = conn.prepare(insert_sql).unwrap();
    // Number of rows submitted in one round trip
    let capacity = source.len();
    // We do not need a nullable buffer since elements of source are not optional
    let descriptions = [A::buffer_desc(false), B::buffer_desc(false)];
    let mut inserter = prepared.column_inserter(capacity, descriptions).unwrap();
    // We send everything in one go.
    inserter.set_num_rows(source.len());
    // Now let's copy the row based tuple into the columnar structure
    for (index, (a, b)) in source.iter().enumerate() {
        inserter.column_mut(0).as_slice::<A>().unwrap()[index] = *a;
        inserter.column_mut(1).as_slice::<B>().unwrap()[index] = *b;
    }
    inserter.execute().unwrap();
}

Required Methods§

Can be used to instantiate a super::ColumnarBuffer. This is useful to allocate the correct buffers in generic code.

Example:

Specification:

use odbc_api::buffers::{Item, BufferDesc};

assert_eq!(BufferDesc::I64{ nullable: true }, i64::buffer_desc(true));
assert_eq!(BufferDesc::I64{ nullable: false }, i64::buffer_desc(false));

Extract the array type from an AnySlice.

Extract the typed nullable buffer from an AnySlice.

Extract the array type from an AnySliceMut.

Extract the typed nullable buffer from an AnySliceMut.

Implementations on Foreign Types§

Implementors§