Rust Backend

Windmill Rust Patterns

Apply these Windmill-specific patterns when writing Rust code in backend/.

Error Handling

Use Error from windmill_common::error. Return Result<T, Error> or JsonResult<T>:

use windmill_common::error::{Error, Result};

pub async fn get_job(db: &DB, id: Uuid) -> Result<Job> {
    sqlx::query_as!(Job, "SELECT id, workspace_id FROM v2_job WHERE id = $1", id)
        .fetch_optional(db)
        .await?
        .ok_or_else(|| Error::NotFound("job not found".to_string()))?;
}

Never panic in library code. Reserve .unwrap() for compile-time guarantees.

SQLx Patterns

Never use SELECT * — always list columns explicitly. Critical for backwards compatibility when workers lag behind API version:

// Correct
sqlx::query_as!(Job, "SELECT id, workspace_id, path FROM v2_job WHERE id = $1", id)

// Wrong — breaks when columns are added
sqlx::query_as!(Job, "SELECT * FROM v2_job WHERE id = $1", id)

Use batch operations to avoid N+1:

// Preferred — single query with IN clause
sqlx::query!("SELECT ... WHERE id = ANY($1)", &ids[..]).fetch_all(db).await?