CrateCache

A decorator that wraps any Crate!T implementation and adds an in-memory cache layer. Cache hits skip the underlying storage entirely.

Setup

import crate.collection.cache;
import crate.collection.mongo;

auto mongoCrate = new MongoCrate!Product(collection);
auto products = new CrateCache!Product(mongoCrate);

router.crateSetup!RestApi.add(products);

How It Works

CrateCache maintains a Json[string] map keyed by _id:

• getItem: Returns cached item if available; otherwise fetches from the wrapped crate and caches the result
• addItem: Inserts via the wrapped crate, then caches the returned item
• updateItem: Updates the cache, then delegates to the wrapped crate
• deleteItem: Removes from cache, then delegates to the wrapped crate
• get (list): Always delegates to the wrapped crate — list queries are not cached

When to Use

• Frequently accessed items that rarely change
• Reducing database load for getItem calls
• Hot data that benefits from in-memory access

The cache has no TTL or eviction — it grows for the lifetime of the process. For production use with large datasets, consider an external cache (Redis, etc.) via a custom crate.