Jeroen Leenarts
76 lines
2.4 KiB
Plaintext
76 lines
2.4 KiB
Plaintext
---
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id: adding_local_data_persistence
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title: Offline Support
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---
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Adding Local Data Persistence for Offline Support
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### Introduction
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Most messaging apps need to work regardless of whether the app is currently connected to the internet.
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Local data persistence stores the fetched data from the backend on a local SQLite database using the
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moor package in Flutter. All packages in the SDK can use local data persistence to store messages
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across multiple platforms.
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### Implementation
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To add data persistence you can extend the class ChatPersistenceClient and pass an instance to the StreamChatClient.
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```dart
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class CustomChatPersistentClient extends ChatPersistenceClient {
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...
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}
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final client = StreamChatClient(
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apiKey ?? kDefaultStreamApiKey,
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logLevel: Level.INFO,
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)..chatPersistenceClient = CustomChatPersistentClient();
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```
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We provide an official persistent client in the [`stream_chat_persistence`](https://pub.dev/packages/stream_chat_persistence)
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package that works using the library [moor](https://moor.simonbinder.eu), an SQLite ORM.
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Add this to your package's `pubspec.yaml` file, using the latest version.
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```yaml
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dependencies:
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stream_chat_persistence: ^latest_version
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```
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You should then run `flutter packages get`
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The usage is pretty simple.
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1. Create a new instance of `StreamChatPersistenceClient` providing `logLevel` and `connectionMode`
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```dart
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final chatPersistentClient = StreamChatPersistenceClient(
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logLevel: Level.INFO,
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connectionMode: ConnectionMode.background,
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);
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```
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2. Pass the instance to the official `StreamChatClient`
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```dart
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final client = StreamChatClient(
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apiKey ?? kDefaultStreamApiKey,
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logLevel: Level.INFO,
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)..chatPersistenceClient = chatPersistentClient;
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```
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And you are ready to go...
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Note that passing `ConnectionMode.background` the database uses a background isolate to unblock the main thread.
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The `StreamChatClient` uses the `chatPersistentClient` to synchronize the database with the newest
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information every time it receives new data about channels/messages/users.
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### Multi-user
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The DB file is named after the `userId`, so if you instantiate a client using a different `userId` you will use a different database.
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Calling `client.disconnectUser(flushChatPersistence: true)` flushes all current database data.
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### Updating/deleting/sending a message while offline
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The information about the action is saved in offline storage. When the client returns online, everything is retried.
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