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Turso WASM Implementation ​

The Turso WASM implementation uses the @tursodatabase/database-wasm library, providing SQLite functionality in web browsers and other WASM-compatible environments.

INFO

This implementation uses SharedArrayBuffer and OPFS which require the following server headers to be set:

  • Cross-Origin-Opener-Policy: same-origin
  • Cross-Origin-Embedder-Policy: require-corp

Installation ​

bash
npm install applesauce-sqlite @tursodatabase/database-wasm

Basic Usage ​

Unlike other implementations, Turso WASM requires you to create and initialize the database instance yourself before passing it to the TursoWasmEventDatabase constructor:

js
import { EventStore } from "applesauce-core";
import { TursoWasmEventDatabase } from "applesauce-sqlite/turso-wasm";
import { connect } from "@tursodatabase/database-wasm";

// Create a database connection
const db = await connect("my-database.db");

// Create and initialize the event database in one step
const database = await TursoWasmEventDatabase.fromDatabase(db);

// Create EventStore with Turso WASM backend
const eventStore = new EventStore(database);

// Use as normal
eventStore.add(someNostrEvent);

Options ​

The TursoWasmEventDatabase.fromDatabase() method accepts the following options:

js
const database = await TursoWasmEventDatabase.fromDatabase(db, {
  search: true, // Enable full-text search (default: false)
  searchContentFormatter: customFormatter, // Custom search content formatter
});

Search Support ​

Enable full-text search using SQLite's FTS5 extension:

js
const database = await TursoWasmEventDatabase.fromDatabase(db, {
  search: true,
});

// Now you can search events
const results = eventStore.getByFilters({
  search: "bitcoin lightning",
});

Custom Search Formatter ​

Customize how content is indexed for search:

js
const database = await TursoWasmEventDatabase.fromDatabase(db, {
  search: true,
  searchContentFormatter: (event) => {
    // Extract searchable content from event
    return event.content + " " + event.tags.map((t) => t[1]).join(" ");
  },
});

Advanced Usage ​

Database Connection Management ​

The Turso WASM implementation requires you to manage the database connection lifecycle:

js
import { connect } from "@tursodatabase/database-wasm";

// Create connection
const db = await connect("my-database.db");

// Create and initialize event database in one step
const database = await TursoWasmEventDatabase.fromDatabase(db, { search: true });

// ... use the database

// Close when done
await database.close();

Using with Existing Database Instance ​

You can use any existing Turso WASM Database instance:

js
import { connect } from "@tursodatabase/database-wasm";
import { TursoWasmEventDatabase } from "applesauce-sqlite/turso-wasm";

// Your existing database setup
const db = await connect("existing-database.db");

// Create and initialize event database in one step
const database = await TursoWasmEventDatabase.fromDatabase(db, { search: true });

Rebuilding Search Index ​

If you need to rebuild the search index (e.g., after changing the search formatter):

js
await database.rebuildSearchIndex();

Closing the Database ​

Always close the database when done:

js
await database.close();

Or use automatic cleanup with Symbol.dispose:

js
{
  const database = await TursoWasmEventDatabase.fromDatabase(db);
  // ... use database
} // Automatically closed when out of scope

Web Browser Example ​

Here's a complete example for use in a web browser:

html
<!DOCTYPE html>
<html>
  <head>
    <title>Nostr Event Database</title>
  </head>
  <body>
    <div id="app"></div>

    <script type="module">
      import { EventStore } from "applesauce-core";
      import { TursoWasmEventDatabase } from "applesauce-sqlite/turso-wasm";
      import { connect } from "@tursodatabase/database-wasm";

      async function initApp() {
        try {
          // Create database connection
          const db = await connect("nostr-events.db");

          // Create and initialize event database with search enabled
          const database = await TursoWasmEventDatabase.fromDatabase(db, {
            search: true,
          });

          // Create event store
          const eventStore = new EventStore(database);

          // Example: Add a test event
          const testEvent = {
            id: "test123",
            kind: 1,
            pubkey: "pubkey123",
            created_at: Math.floor(Date.now() / 1000),
            content: "Hello from Turso WASM!",
            tags: [],
            sig: "signature123",
          };

          await eventStore.add(testEvent);

          // Example: Search events
          const searchResults = eventStore.getByFilters({
            search: "Hello",
            kinds: [1],
          });

          console.log("Search results:", searchResults);

          // Update UI
          document.getElementById("app").innerHTML = `
                    <h1>Nostr Event Database</h1>
                    <p>Database initialized successfully!</p>
                    <p>Found ${searchResults.length} events matching search.</p>
                `;
        } catch (error) {
          console.error("Error initializing app:", error);
          document.getElementById("app").innerHTML = `
                    <h1>Error</h1>
                    <p>Failed to initialize database: ${error.message}</p>
                `;
        }
      }

      initApp();
    </script>
  </body>
</html>