RUST-1243 Failed to deserialize to hashmap when key is enum

[George-Miao]

Versions/Environment

1. What version of Rust are you using?
   rustc 1.61.0-nightly (8d60bf427 2022-03-19) and rustc 1.59.0 (9d1b2106e 2022-02-23)

Not using the latest nightly because ring is broken.

2. What operating system are you using?
   Arch linux 5.16.8-zen1-1-zen

3. What versions of the driver and its dependencies are you using? (Run
   cargo pkgid mongodb & cargo pkgid bson)
   https://github.com/mongodb/mongo-rust-driver.git#mongodb:2.2.0-beta
   https://github.com/rust-lang/crates.io-index#bson:2.2.0-beta

4. What version of MongoDB are you using? (Check with the MongoDB shell using db.version())
   4.4.4

5. What is your MongoDB topology (standalone, replica set, sharded cluster, serverless)?
   standalone

Describe the bug

With structs that have a HashMap<K, V> where K is an enum that implements Hash, mongodb will not correctly deserialize it from the database. This issue only occurs when I use branch 2.2.x. Previous versions that I installed from crates.io works fine. So I assume this is broken by some newly introduced changes.

Output:

Error { kind: BsonDeserialization(DeserializationError { message: "invalid type: string \"Baz\", expected enum Bar" }), labels: {}, wire_version: None, source: None }', src/main.rs:31:46

Code:

use std::collections::HashMap;

use serde::{Deserialize, Serialize};

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
struct Foo {
    map: HashMap<Bar, String>,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Hash)]
enum Bar {
    Baz,
}

#[tokio::main]
async fn main() {
    let col = mongodb::Client::with_uri_str("...")
        .await
        .unwrap()
        .database("test")
        .collection::<Foo>("test");

    col.drop(None).await.unwrap();

    let obj = Foo {
        map: HashMap::from_iter([(Bar::Baz, "1".to_owned()), (Bar::Baz, "2".to_owned())]),
    };

    col.insert_one(&obj, None).await.unwrap();

    let ret = col.find_one(None, None).await.unwrap().unwrap();

    assert_eq!(ret, obj);
}

[abr-egn]

Thank you for the detailed and timely report! I've reproduced this failure locally and am investigating.

[abr-egn]

I just pushed a fix for this to the bson 2.2.x branch - can you update your local environment to use that and verify that it resolves your issue?

[George-Miao]

I just pushed a fix for this to the bson 2.2.x branch - can you update your local environment to use that and verify that it resolves your issue?

Just did the test again, runs perfectlly. Thanks for such a quick update! And may I ask when will this change be published to crates.io?

[abr-egn]

There's another bug I'd like to track down before rolling out a beta.1 release, so probably early next week.

[George-Miao]

There's another bug I'd like to track down before rolling out a beta.1 release, so probably early next week.

I see. Then I shall close the issue.

[abr-egn]

FYI, I just published 2.2.0-beta.1, which contains the fix.