flutter_simple_dependency_injection 1.0.1

flutter_simple_dependency_injection #

A simple dependency injection plugin for Flutter and Dart.

This implementation does not rely on the dart reflection apis (mirrors) and favours a simple factory based approach. This increases the performance and simplicity of this implementation.

  • Support for multiple injectors (useful for unit testing or code running in isolates)
  • Support for types and named types
  • Support for singletons
  • Support simple values (useful for configuration parameters like api keys or urls)

Any help is appreciated! Comment, suggestions, issues, PR's!

Getting Started #

In your flutter or dart project add the dependency:

dependencies:
  ...
  flutter_simple_dependency_injection: any

For help getting started with Flutter, view the online documentation.

Usage example #

Import flutter_simple_dependency_injection

import 'package:flutter_simple_dependency_injection/injector.dart';

Injector Configuration #

As this injector relies on factories rather than reflection (as mirrors in not available in Flutter) each mapped type needs to provide a factory function. In most cases this can just be a simple new object returned function. In slightly more advanced scenarios where the type to be created relies on other types an injector instances is passed into the factory function to allow the type of be created to get other types it depends on (see below for examples).

import 'package:flutter_simple_dependency_injection/injector.dart';

void main() {
  // it is best to place all injector initialisation work into one or more modules
  // so it can act more like a dependency injector than a service locator
  final injector = ModuleContainer().initialise(Injector.getInjector());

  // NOTE: it is best to architect your code so that you never need to
  // interact with the injector itself.  Make this framework act like a depencendy injector
  // by having dependencies injected into objects in their constructors.  That way you avoid
  // any tight coupling with the injector itself.

  // Basic usage, however this kind of tight couple and direct interaction with the injector
  // should be limited.  Instead prefer dependencies injection.

  // simple dependency retrieval and method call
  injector.get<SomeService>().doSomething();

  // get an instance of each of the same mapped types
  final instances = injector.getAll<SomeType>();
  print(instances.length); // prints '3'

  // passing in additional arguments when getting an instance
  final instance =
      injector.get<SomeOtherType>(additionalParameters: {"id": "some-id"});
  print(instance.id); // prints 'some-id'
}

class ModuleContainer {
  Injector initialise(Injector injector) {
    injector.map<Logger>((i) => Logger(), isSingleton: true);
    injector.map<String>((i) => "https://api.com/", key: "apiUrl");
    injector.map<SomeService>(
        (i) => SomeService(i.get<Logger>(), i.get<String>(key: "apiUrl")));

    injector.map<SomeType>((injector) => SomeType("0"));
    injector.map<SomeType>((injector) => SomeType("1"), key: "One");
    injector.map<SomeType>((injector) => SomeType("2"), key: "Two");

    injector.mapWithParams<SomeOtherType>((i, p) => SomeOtherType(p["id"]));

    return injector;
  }
}

class Logger {
  void log(String message) => print(message);
}

class SomeService {
  final Logger _logger;
  final String _apiUrl;

  SomeService(this._logger, this._apiUrl);

  void doSomething() {
    _logger.log("Doing something with the api at '$_apiUrl'");
  }
}

class SomeType {
  final String id;
  SomeType(this.id);
}

class SomeOtherType {
  final String id;
  SomeOtherType(this.id);
}

Multiple Injectors #

The Injector class has a static method [getInjector] that by default returns the default instance of the injector. In most cases this will be enough. However, you can pass a name into this method to return another isolated injector that is independent from the default injector. Passing in a new injector name will create the injector if it has not be retrieved before. To destroy isolated injector instances call their [dispose] method.

  final defaultInjector = Injector.getInjector();
  final isolatedInjector = Injector.getInjector("Isolated");

[1.0.1] - 05/03/2019.

  • Removed dependency on flutter
  • Updated example to explain how to use dependency injection rather than service location

[0.0.4] - 05/07/2018.

  • Added ability to pass in additional arguments in the factory function with a new method call [mapWithParams].
    final injector = Injector.getInstance();
    injector.mapWithParams<SomeType>((i, p) => new SomeType(p["id"]))
    final instance = injector.get<SomeType>(additionalParameters: { "id": "some-id" });
    print(istance.id) // prints 'some-id'
  • Added ability to get all objects of the same mapped type
    final injector = Injector.getInstance();
    injector.map<SomeType>((injector) => new SomeType("0"));
    injector.map<SomeType>((injector) => new SomeType("1"), key: "One");
    injector.map<SomeType>((injector) => new SomeType("2"), key: "Two");
    final instances = injector.getAll<SomeType>();
    print(instances.length); // prints '3'

[0.0.3] - 01/07/2018.

  • Improved injector interface using generic types instead of a passed in a type to key an object factory

The new api to map and get a type instance

    // the new api
    final injector = Injector.getInstance();
    injector.map<SomeType>((i) => new SomeType())
    final instance = injector.get<SomeType>();

The old api to map and get a type instance

    // the old api
    final injector = Injector.getInstance();
    injector.map(SomeType, (i) => new SomeType())
    final instance = injector.get<SomeType>(SomeType);

[0.0.2] - 28/06/2018.

  • Fixed up linting and file formats

[0.0.1] - 28/06/2018.

  • Initial release

example/example.dart

import 'package:flutter_simple_dependency_injection/injector.dart';

void main() {
  // it is best to place all injector initialisation work into one or more modules
  // so it can act more like a dependency injector than a service locator
  final injector = ModuleContainer().initialise(Injector.getInjector());

  // NOTE: it is best to architect your code so that you never need to
  // interact with the injector itself.  Make this framework act like a depencendy injector
  // by having dependencies injected into objects in their constructors.  That way you avoid
  // any tight coupling with the injector itself.

  // Basic usage, however this kind of tight couple and direct interaction with the injector
  // should be limited.  Instead prefer dependencies injection.

  // simple dependency retrieval and method call
  injector.get<SomeService>().doSomething();

  // get an instance of each of the same mapped types
  final instances = injector.getAll<SomeType>();
  print(instances.length); // prints '3'

  // passing in additional arguments when getting an instance
  final instance =
      injector.get<SomeOtherType>(additionalParameters: {"id": "some-id"});
  print(instance.id); // prints 'some-id'
}

class ModuleContainer {
  Injector initialise(Injector injector) {
    injector.map<Logger>((i) => Logger(), isSingleton: true);
    injector.map<String>((i) => "https://api.com/", key: "apiUrl");
    injector.map<SomeService>(
        (i) => SomeService(i.get<Logger>(), i.get<String>(key: "apiUrl")));

    injector.map<SomeType>((injector) => SomeType("0"));
    injector.map<SomeType>((injector) => SomeType("1"), key: "One");
    injector.map<SomeType>((injector) => SomeType("2"), key: "Two");

    injector.mapWithParams<SomeOtherType>((i, p) => SomeOtherType(p["id"]));

    return injector;
  }
}

class Logger {
  void log(String message) => print(message);
}

class SomeService {
  final Logger _logger;
  final String _apiUrl;

  SomeService(this._logger, this._apiUrl);

  void doSomething() {
    _logger.log("Doing something with the api at '$_apiUrl'");
  }
}

class SomeType {
  final String id;
  SomeType(this.id);
}

class SomeOtherType {
  final String id;
  SomeOtherType(this.id);
}

Use this package as a library

1. Depend on it

Add this to your package's pubspec.yaml file:


dependencies:
  flutter_simple_dependency_injection: ^1.0.1

2. Install it

You can install packages from the command line:

with pub:


$ pub get

with Flutter:


$ flutter pub get

Alternatively, your editor might support pub get or flutter pub get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:


import 'package:flutter_simple_dependency_injection/injector.dart';
  
Popularity:
Describes how popular the package is relative to other packages. [more]
91
Health:
Code health derived from static analysis. [more]
100
Maintenance:
Reflects how tidy and up-to-date the package is. [more]
100
Overall:
Weighted score of the above. [more]
96
Learn more about scoring.

We analyzed this package on Jul 15, 2019, and provided a score, details, and suggestions below. Analysis was completed with status completed using:

  • Dart: 2.4.0
  • pana: 0.12.19

Platforms

Detected platforms: Flutter, web, other

No platform restriction found in libraries.

Dependencies

Package Constraint Resolved Available
Direct dependencies
Dart SDK >=2.0.0-dev.35 <3.0.0
Dev dependencies
test any

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