local_value 0.0.1 copy "local_value: ^0.0.1" to clipboard
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A new Flutter package project.

NOTE: SUPER EARLY ALPHA. Most of the implementation is complete. I need to do other homework for today so I can't finish the tests / docs, but this version should be useable.

Features #

helps save / load / delete singletons to local storage.

you can specify if the document is a application document, temporary document, support document, or shared prefrence. The distinction can be found here.

In short:

  • DocumentType.document: data that is user generated and cannot be recreated. (ex. my high score in a local-only game)
  • DocumentType.support: data that is NOT user generated and cannot be recreated. (ex. automatically set config files)
  • DocumentType.temporary: data that can be cleared at any time. (ex. caching a downloaded json)
  • DocumentType.prefs: user prefrences (ex. should the app open in light mode)

NOTE: uses shared_preferences on the backend instead of real files. this is because on web, there is no notion of files.

Use cases #

Saving the logged in user:

class CurrentUser {
    final int id;
    final String name;
    final Color favoriteColor;

    // insert toJson here
    // insert fromJson here
}

final locallyPersistedUser = localSingleton<CurrentUser>(
      documentType: DocumentType.document,
      fileName: 'current_user',
      fromJson: CurrentUser.fromJson,
      toJson: (currentUser) => currentUser.toJson());


//save and load the user to memory like this:
CurrentUser? myCurrentUser = await locallyPersistedUser.read();
await locallyPersistedUser.write(someUser);

Caching many things to memory to avoid redundant network calls:

class CurrentUser {
    final int id;
    final String name;
    final Color favoriteColor;

    // insert toJson here
    // insert fromJson here
}

final userCache = LocalSingleton<UserCache>(
  fileName: 'current_user'
);

await UserCache(userId: 1).save(maybeUserOne);

Usage #


//preface: import it!
import 'package:local_value/local_value.dart';

//first, create some sort of data model you want to save to local storage.
//can be a primative (just use LocalJsonFile<int> or similar)
class CounterObj {
    int value;

    CounterObj(this.value);
}


//then, call localJsonFile to build a localJsonFile:

//localJson File
final counterFile = localJsonFile<CounterObj>(
      documentType: DocumentType.document,
      fileName: 'counter',
      fromJson: (counterJson) => CounterObj(counterJson['value'] as int),
      toJson: (counterObj) => {'value': counterObj.value});

//or LocalTxtFile
localTxtFile(documentType: DocumentType.document, fileName: 'counter')


//read from it
CounterObj? myCurrentCounter = await counterStorage.read();

//write to it
await counterStorage.write(myCurrentCounter ?? CounterObj(8));

//clear it
await counterStorage.clear();

Integration with Dependency Injection #

If you're looking to integrate with dependency injection for testing, look no further. The underlying classes (LocalTxtFile and LocalJsonFile) are exposed, so that you can subclass them. Something like this wouldn't work:

//DON'T DO THIS! THIS WILL NOT WORK.
getIt.registerSingleton(localTxtFile(fileName: 'blah1', documentType: ...));
getIt.registerSingleton(localTxtFile(fileName: 'blah2', documentType: ...)); //this will fail, since LocalTxtFile already registered

instead, we can subclass TxtFile:

class BlahOne extends LocalTxtFile {
  BlahOne() : super(
    documentType: DocumentType.document,
    fileName: 'blah1'
  );
}

class BlahTwo extends LocalTxtFile {
  BlahTwo() : super(
    documentType: DocumentType.document,
    fileName: 'blah2'
  );
}

//now we can register them inside get_it:
getIt.registerSingleton(BlahOne());
getIt.registerSingleton(BlahTwo());

Additional information #

If you find an issue, please post it on the github.

I will be back if it proves useful to flesh it out! PR's welcome!

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A new Flutter package project.

Repository (GitHub)
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License

unknown (license)

Dependencies

flutter, path_provider, shared_preferences

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