Function diesel::pg::expression::functions::array_position

pub fn array_position<Arr: ArrayOrNullableArray<Inner = E> + SingleValue, E: SingleValue, a, elem>(
    a: a,
    elem: elem,
) -> array_position<Arr, E, a, elem>
where
    a: AsExpression<Arr>,
    elem: AsExpression<E>,

Available on crate feature postgres_backend only.

Returns the subscript of the first occurrence of the second argument in the array, or NULL if it’s not present. If the third argument is given, the search begins at that subscript. This function omits the third argument. See [array_position_with_subscript].

The array must be one-dimensional. Comparisons are done using IS NOT DISTINCT FROM semantics, so it is possible to search for NULL.

Example

let pos = diesel::select(array_position::<Array<_>, Integer, _, _>(vec![1, 2, 3, 4], 3))
    .get_result::<Option<i32>>(connection)?;
assert_eq!(Some(3), pos);

let pos = diesel::select(array_position::<Array<_>, Integer, _, _>(vec![1, 2, 3, 4], 5))
    .get_result::<Option<i32>>(connection)?;
assert_eq!(None::<i32>, pos);

let pos = diesel::select(array_position::<Array<_>, Nullable<Integer>, _, _>(
    vec![1, 2, 3, 4], None::<i32>))
    .get_result::<Option<i32>>(connection)?;
assert_eq!(None::<i32>, pos);

let pos = diesel::select(array_position::<Array<_>, Nullable<Integer>, _, _>(
    vec![None::<i32>, Some(1), Some(2), Some(3)], None::<i32>))
    .get_result::<Option<i32>>(connection)?;
assert_eq!(Some(1), pos);

let dims = diesel::select(array_position::<Nullable<Array<Integer>>, Integer, _, _>(None::<Vec<i32>>, 1))
    .get_result::<Option<i32>>(connection)?;
assert_eq!(None, dims);