Chapter 9. Building Offline Apps with Amplify DataStore

So far in this book, we’ve worked with REST APIs and GraphQL APIs. When working with the GraphQL APIs, we used the API class to directly call mutations and queries against the API.

Amplify also supports another type of API for interacting with AppSync: Amplify DataStore. DataStore has a different approach than a traditional GraphQL API.

Instead of interacting with the GraphQL API itself, using queries and mutations, DataStore introduces a client-side SDK that allows you to write to and read from a local store and persists this data locally using the local storage engine of the platform you are working with (i.e., IndexDB for web and SQLite for native iOS and Android). DataStore then automatically syncs the local data to the GraphQL backend for you as updates are made both locally and remotely.

Using the DataStore SDK, you then only have to perform the operations like save, update, and delete, writing directly to DataStore itself. DataStore handles everything else for you: it syncs your data to the cloud when you have an internet connection, and if you’re not online, will queue it for the next time you’re connected.

DataStore also handles conflict detection and resolution for you with one of three built-in conflict-resolution strategies:

AutoMerge

GraphQL type information on an object is inspected at runtime to perform merge operations (suggested option).

Optimistic concurrency

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