Dependency injection: What is it and how to implement it in Flutter App Development

Flutter app development is thriving thanks to the growing interest of entrepreneurs and app developers alike. An active community has made Flutter a choice of hundreds of thousands of companies globally. Particularly, Flutter has many features and tools that reduce the duration of the app development process and assist developers to come up with a seamlessly-performing app. For example, Dependency Injection or DI is one of them.

Dependency injection for Flutter app development
Dependency injection for Flutter app development

Using DI, we move the creation and binding of the dependent objects outside of the class that depends on them. Thus, it brings a higher level of flexibility, decoupling, and easier testing. So now, we – ArrowHiTech would like to introduce to you guys the dependency injection definition, as well as the way to implement it in your Flutter app development. Without further ado, let’s get into the basics.

Before moving to the way to implement it in your Flutter app development, let’s take a look at the Dependency injection definition

Dependency injection definition

Dependency Injection is a way of making the dependencies of an object available via another object, and these dependencies are usually known as services. These services can be blocks of code, containing different functionalities that can be easily reused in different parts of your project. Specifically, dependencies are functionalities required by parts of your project to run successfully.

That is all about dependency injection definition. If you are pretty sure about dependency injection definition, let’s read continue.

How to implement dependency injection in your Flutter app development?

Now, we are going to understand different methods to implement DI. We have many ways by which we can implement DI in Flutter, to mention a few:

1. Passing object through constructor argument

Let’s start with the first and most simple way to implement dependency injection: Passing object through constructor argument. We can create an object of the dependent class in the parent level and pass the object through the constructor of the child. Here we take one example to understand more about this type of DI. Let’s assume that we have one ApiService() call in which we have written our all API related calls. 

2. Inherited widget

Inherited widget is Provided by a flutter, no need to add any new dependency injection for this. The inherited widget allows you to pass the data deep down to the widget tree. Let’s create one inherited widget. This is the component which generated by the Flutter VS code extension. Then, let’s understand this code one by one.

  • This widget accepts one widget, here we name that widget as a child(you can give any name you want). For this, we have to pass the widget tree in which we want to pass objects.
  • The next part of the code looks up to the widget tree and finds closets InheritedWidget and registers the BuildContext with that widget so whenever widget change than it can rebuild the tree.
  • updateShouldNotify() method returns boolean that states whether sub widget tree will be rebuilt or not when change occurs in InheritedWidget.

3. IOC package

Ioc is stood for inversion of control which is the underlying principle of dependency injection. This IOC package state pattern which says that all the services and dependencies must be in separate files. Since it is easy to use, it allows you to initialize your services as a singleton and you can bind your dependency of any data type you want. Therefore, all you have to do is make some changes, and import ApiService object. After all, it should look like this:

4. Get_it package for dependency injection

Get_it is one of the most popular ways to handle DI in the flutter app. Above all the way we had to use our dependency as a singleton way, but by using this package we can import our dependency in many ways like lazy Singleton, Singleton, factory. Now let’s understand all these three concepts in deep.

  • Singleton: This always returns the same instance of that particular service.
  • Lazy singleton: This method creates an instance of a particular service when it called the first time. this is used when we have service which takes time to start and should start when it’s required.
  • Factory: This returns a new instance of service whenever we called.

Now let’s see how can we implement get_it to package in our dependency injection project. The example below will show you how:

Final words

That should probably be it! Here is the complete dependency injection definition, as well as some ways to implement it in your Flutter app development. All in all, this term helps Flutter app development provide the same UI and business logic across all platforms. With excellent features and functionality, this framework is capable of developing feature-rich apps for your enterprise.

In case you have any ideas about dependency injection definition or some ways to implement it in your Flutter app development. If you have any questions, don’t hesitate to request a Free Consultation