How do I serialize chrono::DateTime fields as ISODate when using the Rust Mongo driver prototype?

Question

Datetime fields in structs are being serialized to Strings instead of ISODates when using the Rust Mongo driver prototype. How do I get the fields to be saved as ISODate?

use chrono::{DateTime, Utc};
use mongodb::oid::ObjectId;
use mongodb::{
    coll::Collection, db::Database, db::ThreadedDatabase, error::Error, Client, ThreadedClient,
};
use serde::{Deserialize, Serialize};

#[derive(Serialize, Deserialize, Clone, Debug)]
struct Person {
    pub _id: ObjectId,
    pub date: DateTime<Utc>,
}

fn main() {
    let client = Client.with_uri("mongodb://localhost:27017").unwrap();
    let p = Person {
        _id: ObjectId::new().unwrap(),
        date: Utc::now(),
    };
    let document = mongodb::to_bson(p).unwrap().as_document();
    if document.is_some() {
        client
            .db("my_db")
            .collection("mycollection")
            .insert_one(document, None)
            .unwrap();
    }
}

On querying the DB, the record contains a date string (in ISO format); I expected it to be an ISODate.

Answer 1

You can choose deserialization as ISO string with serde_helpers.

https://docs.rs/bson/1.2.2/bson/serde_helpers/index.html

use mongodb::bson::DateTime;
use mongodb::bson::serde_helpers::bson_datetime_as_iso_string;

#[derive(Serialize, Deserialize, Clone, Debug)]
struct Person {
    pub _id: ObjectId,
    #[serde(with = "bson_datetime_as_iso_string")]
    date: DateTime,
}

Answer 2

With mongodb and bson crates in version 2.0.0-beta.1

In Cargo.toml, add the feature chrono-0_4:

bson = { version = "2.0.0-beta.1", features = ["chrono-0_4"] }

Then annotate your field with

use chrono::{DateTime, Utc};

#[serde(with = "bson::serde_helpers::chrono_datetime_as_bson_datetime")]
date: DateTime<Utc>,