How to query a Timestamptz with a Unix timestamp using Diesel? - postgresql

Question

I can easily get the system Unix millisecond timestamp, but how can I convert it into something I can query with Diesel? The table in my schema has a Timestampz field (timestamp with time zone) that I need to compare to the Unix timestamp.
use diesel::sql_types::Timestamptz;
fn main() {
let unix_time: i64 = 123456;
let time: Timestamptz = ???
}
[dependencies]
diesel = { version = "1.4.7", features = ["postgres"] }

Answer 1

Timestamptz can be created from a PgTimestamp, chrono::NaiveDateTime or chrono::DateTime according to the docs.
I don't think there is a direct way to generate a timestamptz, and it's supposed to be opaque in most instances. Instead where a queries requires a Timetamptz you can pass a NaiveDateTime and load a NaiveDateTime back.
Now we use NaiveDateTime as it's the only one that can be created from a unix timestamp. DateTime requires an explicit timezone and can be generated from a NaiveDateTime.
use chrono::NaiveDateTime;
fn main() {
let conn = get_connection();
let ndt = NaiveDateTime::from_timestamp(0, 42_000_000);
let (id, date) = users
// assume a "created" column being a Timestamptz
// you can just pass a NaiveDateTime.
.filter(created.gt(ndt))
.select((user_id, created))
// We load back a NaiveDateTime and never deal with Timestamptz directly.
.first::<(u64, NaiveDateTime)>(&conn)
.expect("query failed");
}