![]() Then I obtain the service: MyService service retrofit.create(MyService.class) Note that I do not write the code of this service, as retrofit works it generate the service automatically using my interface (MyService) annotations. Override fun enqueue( callback : Callback>) Ĭallback.onResponse( Response. It generate the service for my interface and use Gson to parse the response wrapping it with RxJava Observable. All subclasses of a sealed class are known at compile-time, which allows you to use them exhaustively in the when expression.Īs you’ve seen in the figure above, there are typically three scenarios where you’d want to construct a sealed class: Add it to your adle like so: compile 2:adapter-rxjava2:2.3.0. Sealed classes represent quite more restricted class hierarchies than normal classes in Kotlin. You need to register a call adapter factory with Retrofit that can create RxJava types. Modeling Retrofit Responses With Sealed Classes/Interfaces Retrofit is a REST Client for Java and Android allowing to retrieve and upload JSON (or other structured data) via a REST based You can configure which converters are used for the data serialization, example GSON for JSON. 139 comments, 3 shares, Facebook Watch Videos from The Retrofit Source: We NEED. Let’s see how to construct the wrapper class with a sealed class. Please use best practices if you perform this job such as soldering iron. For example, configuring UI elements and displaying a different placeholder/toast depending on error types. Usually, youll want to execute the request asynchronously with the enqueue method. ![]() So how do you solve this problem? It’s simple: Wrap every possible scenario of an API response with a sealed class as in the figure below:īy passing a wrapper class to the call site, the presentation layer can handle results depending on the response type. The Call class is the starting point for every network request with Retrofit. This means you should write lots of try-catch boilerplate code for each API request. You also need to handle exceptions somewhere in this multi-layer architecture, because API calls may throw an exception and it can be propagated to the call site. So if you return an empty list or null when the network request fails, other layers have no idea how to figure out whether the request was successful or not. To make this point clear assume that we need to send user. The fetchPoster function may return an empty list if the body of the API response is empty. What is Retrofit Simply if you need to send or receive data from server you need to serialize data to be able to retrieve it. In this architecture, you will face the following problem: results are ambiguous on call sites. We'll build an example application interacting with the GitHub API using the standard Retrofit approach, and then we'll enhance it using RxJava to leverage the advantages of Reactive Programming. But suppose you need to handle the response and exceptions in a multi-layer architecture as in the API data flow below: This article focuses on how to implement a simple RxJava-ready REST Client using Retrofit. but my variable gets null at first and after seconds, when retrofit completed its task, my variable gets data but log value doesn't update.This snippet is a basic example of calling the Retrofit API and handling the response. ![]() I have a button in my view and when I click on it, the request method gets to start and subscription write a log of its own data. I config retrofit, and also use observable and subscribe in ViewModel to make observable variable to use in activity binding layout. I'm new in kotlin and I'm trying to use retrofit with Rxjava and live data in MVVM architecture.
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