如何转换Vec <i32> 到类型:: array :: ArrayBase <Option<i32> &gt;对于锈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();

This results in the error:

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

According to the documentation , this means that I need to convert it to types::array::ArrayBase<Option<i32>> .

How do I do this?

---

My best attempt so far is:

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();

Which results in:

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

The trick lied in dereferencing the pointer within the closure function in map |i| Some(*i) |i| Some(*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();

I'll award the answer to someone who can find a more elegant/ idiomatic way of doing this.

Answer 2

Try with either ArrayBase::from_raw or ArrayBase::from_vec . They are documented - you can either read the source code or build the docs with rustdoc.

https://github.com/sfackler/rust-postgres/blob/master/src/types/array.rs