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Reading data

Sometimes you just need to fetch data once without subscribing to ongoing changes. The Lark SDK provides two equivalent methods for this.

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once(eventType)

Reads data at a reference and returns a promise that resolves with a DataSnapshot: 
import { LarkDatabase } from "@lark-sh/client";

const db = new LarkDatabase("my-project/my-database");
await db.connect({ anonymous: true });

const snapshot = await db.ref("users/alice").once("value");

console.log(snapshot.val());
// { name: "Alice", score: 42, online: true }

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get()

An alias for once('value'). Same behavior, shorter syntax: 
const snapshot = await db.ref("users/alice").get();

console.log(snapshot.val());
// { name: "Alice", score: 42, online: true }

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Working with snapshots

Both methods return a DataSnapshot. Here are the key properties and methods:

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snapshot.val()

Returns the data as a JavaScript value (object, array, string, number, boolean, or null): 
const snapshot = await db.ref("users/alice").get();
const user = snapshot.val(); // { name: "Alice", score: 42 }

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snapshot.exists()

Returns true if data exists at this location, false if it’s null: 
const snapshot = await db.ref("users/nonexistent").get();

if (snapshot.exists()) {
  console.log(snapshot.val());
} else {
  console.log("No data here");
}

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snapshot.key

The key (last path segment) of the location this snapshot represents: 
const snapshot = await db.ref("users/alice").get();
console.log(snapshot.key); // "alice"
If you need data that stays up to date as it changes, use real-time subscriptions instead. once() and get() fetch a single point-in-time snapshot and don’t update afterward.