Function array_prepend 

pub fn array_prepend<T: SingleValue, Arr: ArrayOrNullableArray<Inner = T> + SingleValue, e, a>(
    e: e,
    a: a,
) -> array_prepend<T, Arr, e, a>
where
    e: AsExpression<T>,
    a: AsExpression<Arr>,

Available on crate feature postgres_backend only.

Prepends an element to the beginning of an array

Example

let ints = diesel::select(array_prepend::<Integer, Array<_>, _, _>(3, vec![1, 2]))
    .get_result::<Vec<i32>>(connection)?;
assert_eq!(vec![3, 1, 2], ints);

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

let ints = diesel::select(array_prepend::<Integer, Nullable<Array<_>>, _, _>(
    3,
    None::<Vec<i32>>,
))
.get_result::<Vec<i32>>(connection)?;
assert_eq!(vec![3], ints);

let ints = diesel::select(
    array_prepend::<Nullable<Integer>, Nullable<Array<_>>, _, _>(None::<i32>, None::<Vec<i32>>),
)
.get_result::<Vec<Option<i32>>>(connection)?;
assert_eq!(vec![None], ints);