Hasura Package

This package is a fork of hasura_connect package

Connect your Flutter/Dart apps to Hasura simply.

What can he do

This package is designed to facilitate Hasura's integration with Flutter applications, leveraging the full power of Graphql.

  • Use Query, Mutation and Subscriptions the easy way.
  • Offline cache for Subscription and Mutation made from a Snapshot.
  • Easy integration with leading dart providers (Provider, bloc_pattern).
  • Pass your JWT Token easily if you are informed when it is invalid.

Install

Add dependency in your pubspec.yaml file:

dependencies:
  hasura:

Usage

A simple usage example:


//import
import 'package:hasura/hasura.dart';

String url = 'http://localhost:8080/v1/graphql';
HasuraConnect hasuraConnect = HasuraConnect(url);

You can encapsulate this instance into a BLoC class or directly into a Provider.

Create a document with Query:

//document
String docQuery = """
  query {
    authors {
        id
        email
        name
      }
  }
""";

Now just add the document to the "query" method of the HasuraConnect instance.

//get query
var r = await hasuraConnect.query(docQuery);

//get query with cache
var r = await hasuraConnect.cachedQuery(docQuery);

//OR USE MUTATION
var r = await hasuraConnect.mutation(docQuery);

Subscriptions

Subscriptions will notify you each time you have a change to the searched items. Use the "hasuraConnect.subscription" method to receive a stream.

Snapshot snapshot = hasuraConnect.subscription(docSubscription);
  snapshot.listen((data) {
    print(data);
  }).onError((err) {
    print(err);
  });

Subscription Converter

Use the Map operator to convert json data to a Dart object;

Snapshot<PostModel> snapshot = hasuraConnect
                                  .subscription(docSubscription)
                                  .convert((data) => PostModel.fromJson(data),
                                        cachePersist: (PostModel post) => post.toJson(),
                                      );

snapshot.listen((PostModel data) {
   print(data);
 }).onError((err) {
   print(err);
 });

Using variables

Variables maintain the integrity of Querys, see an example:


String docSubscription = """
  subscription algumaCoisa($limit:Int!){
    users(limit: $limit, order_by: {user_id: desc}) {
      id
      email
      name
    }
  }
""";

Snapshot snapshot = hasuraConnect.subscription(docSubscription, variables: {"limit": 10});

//change values of variables for PAGINATIONS
snapshot.changeVariable({"limit": 20});

Authorization (JWT Token)

View Hasura's official Authorization documentation.


String url = 'http://localhost:8080/v1/graphql';
HasuraConnect hasuraConnect = HasuraConnect(url, token: (isError) async {
  //sharedPreferences or other storage logic
  return "Bearer YOUR-JWT-TOKEN";
});

CACHE OFFLINE

  • Offline caching works with subscriptions automatically.
  • A good strategy for mutation caching is to add the offline object to the snapshot with the add parameter with what will be the change, then perform the mutation.
  • When a mutation internet error occurs, HasuraConnect will attempt to mutate again when the device reconnects to the internet.
  • Use this information to promote your offline persistence rules.
Snapshot snapshot = connect.subscription(...);

//Add object to cache of snapshot
var list = snapshot.value;
list.add(newItem);
snapshot.add(newItem);

//exec asinc mutation
conn.mutation(...);

Custom Database by Delegate

You can add others database to work with cache using localStorageDelegate param in HasuraConnect construct.

This library have two delegates:

  • LocalStorageSharedPreferences (default)
  • LocalStorageHive (Using Hive Database for Desktops)

Implements LocalStorage interface and use any Database:

HasuraConnect hasuraConnect = HasuraConnect(url,
            localStorageDelegate: () => LocalStorageHive(),);

Dispose

HasuraConnect provides a dispose() method for use in Provider or BlocProvider. Subscription will start only when someone is listening, and when all listeners are closed HasuraConnect automatically disconnects.

Therefore, we only connect to Hasura when we are actually using it;

Roadmap

This is currently our roadmap, please feel free to request additions/changes.

FeatureProgress
Queries
Mutations
Subscriptions
Change Variable in Subscriptions
Auto-Reconnect
Dynamic JWT Token
bloc_pattern Integration
Provider Integration
Variables
Cache Subscription
Cache Mutation
Cache Query

Features and bugs

Please send feature requests and bugs at the issue tracker.

Libraries

hasura
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