postgresql - 如何将 Vec<i32> 转换为 types::array::ArrayBase<Option<i32>> 用于 rust-postgres？

Question

let ids: Vec<i32> = get_ids(); //get_ids impl elsewhere
let stmt = db_conn.prepare(
    "SELECT id, name, created FROM person
    WHERE id = ANY( $1 )").unwrap();
let mut iter = stmt.query(
    [&ids]).unwrap();

这会导致错误:

error: failed to find an implementation of trait postgres::types::ToSql for collections::vec::Vec<i32>

根据 the documentation , 这意味着我需要将其转换为 types::array::ArrayBase<Option<i32>> .

我该怎么做？

---

到目前为止我最好的尝试是:

let idOptions: Vec<Option<i32>> = ids.iter().map( |i| Some(i) ).collect();
let idsForDb: postgres::types::array::ArrayBase<Option<i32>> =
    postgres::types::array::ArrayBase::from_vec(idOptions, 0);
let mut iter = stmt.query(
    [&idsForDb]).unwrap();

结果是:

error: expected core::iter::FromIterator<core::option::Option<&i32>>, but found core::iter::FromIterator<core::option::Option<i32>> (expected i32 but found &-ptr) [E0095]

Answer 1

技巧在于在 map |i| 的闭包函数中取消引用指针一些(*i):

let idOptions: Vec<Option<i32>> = ids.iter().map( |i| Some(*i) ).collect();
let idsForDb: postgres::types::array::ArrayBase<Option<i32>> =
    postgres::types::array::ArrayBase::from_vec(idOptions, 0);
let mut iter = stmt.query(
    [&idsForDb]).unwrap();

我会将答案奖励给能够找到更优雅/惯用的方法的人。