Quick Start - Node.js SDK

Import Realm

At the top of your source files where you want to use Realm, add the following line to import the SDK.

import Realm, { ObjectSchema } from "realm";

Define Your Object Model

Your application's object model defines the data that you can store within Realm.

To define a Realm object type, create a schema object that specifies the type's name and properties. The type name must be unique among object types in a realm. For details on how to define specific properties, see Define Object Properties.

The following code shows how to define an object model for a Task object. In this example:

• The primaryKey is the _id of type int. Another common type used for primary keys is ObjectId.

• The name field is required.

• The status and owner_id fields are optional, denoted by the question mark immediately after the data type.

Open a Realm

To open a realm, pass a Realm.BaseConfiguration object to Realm.open().

Find, Sort, and Filter Objects

The following code demonstrates how to:

• Query for all instances of the "Task" object type.

• Filter the query to retrieve only the tasks that are "Open".

• Sort the tasks by the name in an ascending order.

// Query for specific obect using primary key.
const specificTask = realm.objectForPrimaryKey(Task, 0);
// Query realm for all instances of the "Task" type.
const tasks = realm.objects(Task);
// Filter for all tasks with a status of "Open".
const openTasks = tasks.filtered("status = 'Open'");
// Sort tasks by name in ascending order.
const tasksByName = tasks.sorted("name");

Create, Modify, and Delete Realm Objects

Once you have opened a realm, you can create, modify, and delete objects in it. All write operations must occur within a write transaction.

const allTasks = realm.objects(Task);
// Add a couple of Tasks in a single, atomic transaction.
realm.write(() => {
  realm.create(Task, {
    _id: 1,
    name: "go grocery shopping",
    status: "Open",
  });
  realm.create(Task, {
    _id: 2,
    name: "go exercise",
    status: "Open",
  });
});
const task1 = allTasks.find((task) => task._id == 1);
const task2 = allTasks.find((task) => task._id == 2);
realm.write(() => {
  // Modify an object.
  task1!.status = "InProgress";
  // Delete an object.
  realm.delete(task2);
});

Watch a Collection

You can watch a realm, collection, or object for changes by registering event handlers with the Realm.addListener() Object.addListener() Collection.addListener() methods.

In the following example, an application developer watches for changes to the Task collection.

Close a Realm

Call the realm.close() method when done with a realm instance to avoid memory leaks.

// Close the realm.
realm.close();

Add Device Sync (Optional)

This section illustrates how to authenticate with an Anonymous User and open a Flexible Sync realm to sync data between devices.

// Initialize your App.
const app = new Realm.App({
  id: "<yourAppId>",
});

// Initialize your App.
const app = new Realm.App({
  id: "<yourAppId>",
});
// Authenticate an anonymous user.
const anonymousUser = await app.logIn(Realm.Credentials.anonymous());

class Task extends Realm.Object<Task> {
  _id!: number;
  name!: string;
  status?: string;
  owner_id?: string;
  static schema: ObjectSchema = {
    name: "Task",
    properties: {
      _id: "int",
      name: "string",
      status: "string?",
      owner_id: "string?",
    },
    primaryKey: "_id",
  };
}