Firestore for Rust

Caching named documents instead of a whole collection

.collection(name) subscribes the listener to the entire collection, even though it does not preload it - “lazy” only means the initial download is skipped. When you know which documents you care about, say so:

use firestore::*;
async fn example(db: FirestoreDb) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
let cache = FirestoreCache::memory(&db)
    .collection_with("configs", |c| {
        c.documents(["site", "billing"]).preload_all()
    })
    .build()
    .await?;
let _ = cache;
Ok(())
}

The listener then watches exactly those documents, so unrelated changes in the collection are never streamed to your process or written into the cache, and preloading reads just those IDs. This is the shape to reach for with configuration, feature flags and reference data.

Such a collection is never listable, whatever its load mode: it holds a chosen subset, so list and query would return a partial answer that looks complete.