Rust mongodb driver auto indexing helper

indexing.rs

use mongodb::{ bson::doc, options::IndexOptions, Collection, Database, IndexModel };

pub async fn auto_indexing_collection<T>(db: Database, key: Vec<String>, collection_name: String)
    where T: serde::Serialize + serde::de::DeserializeOwned + Unpin + Send + Sync
{
    let options = IndexOptions::builder().unique(true).build();
    let collection: Collection<T> = db.collection(&collection_name);
    for k in key {
        let model = IndexModel::builder()
            .keys(doc! { k : 1 })
            .options(options.clone())
            .build();
        collection.create_index(model).await.expect("creating an index should succeed");
    }
}