Memory Storage

The MemoryStorageAdapter implements the full DatafnStorageAdapter interface using in-memory JavaScript Map objects. Data does not persist across page reloads or process restarts.

Use Cases

Testing -- Fast, deterministic storage for unit and integration tests.
Server-side rendering -- Temporary storage during SSR where IndexedDB is not available.
Non-browser environments -- Node.js scripts, CLI tools, or any environment without IndexedDB.

Usage

import { MemoryStorageAdapter } from "@datafn/client";

// Basic usage
const storage = new MemoryStorageAdapter();

// With resource validation
const storage = new MemoryStorageAdapter(["todos", "projects"]);

When a list of resource names is provided, the adapter validates table names on every operation and throws an error for unknown resources. The built-in kv resource is always registered automatically.

Behavior

The MemoryStorageAdapter provides the same semantics as the IndexedDB adapter:

Deterministic ordering -- listRecords returns records sorted by id ascending. listJoinRows sorts by composite from:to key.
Changelog deduplication -- changelogAppend deduplicates by (clientId, mutationId) pair using an O(1) Map index.
Atomic merge -- mergeRecord performs a read-modify-write with one-level-deep merge for object fields.
Hydration state validation -- State transitions are validated (e.g., cannot go from ready to notStarted).
Cursor validation -- Cursor values are validated before storage.

Example: Testing

import { MemoryStorageAdapter } from "@datafn/client";
import { createDatafnClient } from "@datafn/client";

const storage = new MemoryStorageAdapter(["todos"]);

const client = createDatafnClient({
  schema,
  storage,
});

// Storage is pre-populated for testing
await storage.upsertRecord("todos", { id: "t1", title: "Test todo" });
await storage.setHydrationState("todos", "ready");

// Queries now run against in-memory storage
const result = await client.table("todos").query({});

Lifecycle

// No-op (no external connections to close)
await storage.close();

// Clears all data, resets changelog sequence, recreates KV store
await storage.clearAll();

// Always returns healthy
const { ok } = await storage.healthCheck(); // { ok: true, issues: [] }