Function state_transition

FullStackRust/backend/src/api/task.rs:94–119

(
    ddb_repo: Data<DDBRepository>, 
    task_global_id: String,
    new_state: TaskState,
    result_file: Option<String>
)

}

async fn state_transition(
    ddb_repo: Data<DDBRepository>, 
    task_global_id: String,
    new_state: TaskState,
    result_file: Option<String>
) -> Result<Json<TaskIdentifier>, TaskError> {
    let mut task = match ddb_repo.get_task(
        task_global_id
    ).await {
        Some(task) => task,
        None => return Err(TaskError::TaskNotFound)
    };

    if !task.can_transition_to(&new_state) {
        return Err(TaskError::BadTaskRequest);
    };
    
    task.state = new_state;
    task.result_file = result_file;

    let task_identifier = task.get_global_id();
    match ddb_repo.put_task(task).await {
        Ok(()) => Ok(Json(TaskIdentifier { task_global_id: task_identifier })),
        Err(_) => Err(TaskError::TaskUpdateFailure)
    }
}

#[put("/task/{task_global_id}/start")]
pub async fn start_task(