RelationDef is not Send

[smrtrfszm]

Description

The type RelationDef is not Send, which broke a lot of code in multithreaded environments, because async runtimes needs Futures which implement Send.

Steps to Reproduce

Compile example code below

Expected Behavior

Should compile

Actual Behavior

It doesn't compiles, because tokio::spawn expects a Future that is Send.

Reproduces How Often

always

Versions

sea-orm: v0.9.0
database: sqlite (but it happens with all of them)
OS: Arch Linux kernel 5.18.10

Additional Information

Example code that compiles on sea-orm v0.8.0, but not on v0.9.0

Cargo.toml:

[package]
name = "send"
version = "0.1.0"
edition = "2021"

[dependencies]
sea-orm = { version = "0.9.0", features = ["sqlx-sqlite", "runtime-tokio-rustls", "macros"], default-features = false }
tokio = { version = "1.20.0", features = ["rt-multi-thread", "macros"] }

main.rs:

use sea_orm::tests_cfg::{cake, cake_filling};
use sea_orm::{Database, DbErr, EntityTrait, JoinType, QuerySelect, RelationTrait};

#[tokio::main]
async fn main() -> Result<(), DbErr> {
    let db = Database::connect("sqlite::memory:").await?;

    tokio::spawn(async move {
        let _cakes = cake::Entity::find()
            .join_rev(JoinType::InnerJoin, cake_filling::Relation::Cake.def())
            .all(&db)
            .await
            .unwrap();
    })
    .await
    .unwrap();

    Ok(())
}

Possible solution is to make the field on_condition in RelationDef Send by just adding + Send to it. It shouldn't be a big constraint in my opinion as most of the types are Send, but also it is a breaking change.

[billy1624]

Hey @smrtrfszm, thanks for the reporting! I've opened a PR to fix this

[billy1624]

This issue is caused by #793 which introduced on_conflict but without marking it as Send & Sync