Quick Start

Create

To instantiate a new object and add it to the database in a write block:

For more information, refer to Create Objects.

Read and Filter

To retrieve a results collection of all objects of a given type in the database:

For more information, refer to Read Objects.

To filter that same results collection:

For more information about the SDK query engines, refer to Filter Data.

Update

To modify an object, update its properties in a write transaction block:

For more information, refer to Update Objects.

Delete

To delete an object from the database:

For more information, refer to Delete Objects.

Prerequisites

Before you can sync device data, you must:

• Create an App Services App

• Enable anonymous authentication

• Enable Device Sync with Development Mode toggled to On.

• Define the rules that determine which permissions users have when using Device Sync.

Initialize the App

The SDK uses an App to connect to Atlas, manage users, and report certain types of errors.

To use App Services features such as authentication and sync, access your App Services App using your App ID. You can find your App ID in the App Services UI.

To initialize the App connection:

For more details about configuring and initializing the App connection, refer to Connect to Atlas.

Authenticate a User

This quick start uses anonymous authentication to log in users without requiring them to provide any identifying information. After authenticating the user, you can open a database for that user.

The SDK provides additional ways to authenticate, register, and link users. For other authentication providers, refer to Authenticate Users.

Open a Synced Database

For more details about opening a synced database, refer to Configure & Open a Synced Database.

For more details about Sync subscriptions, refer to Manage Sync Subscriptions.

Read, Write, and React to Changes

The syntax to read, write, and watch for changes on a synced database is identical to the syntax for non-synced databases above.

However, reads and writes to a synced databases have the following additional constraints:

• Sync permissions that determine whether users can read or write.

• Sync subscriptions that determine what data the synced database can read or write.

In the following example, we set Sync permissions to Users can only read and write their own data, and add a property that lets us subscribe to only the current user's todos. Users can only read and write their own data.

For more information about Device Sync permissions, refer to Role-based Permissions in the App Services documentation.

While you work with local data, a background thread efficiently integrates, uploads, and downloads changesets.

Every write transaction for a subscription set has a performance cost. If you need to make multiple updates to a database object during a session, consider keeping edited objects in memory until all changes are complete. This improves sync performance by only writing the complete and updated object to your database instead of every change.