How to Parse a No Key JSON List with Moshi in Android

Описание: Learn how to handle a `No Key` JSON array response from the GitHub API using Moshi in Android. We'll take you through the setup and the necessary modifications to avoid errors.
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This video is based on the question https://stackoverflow.com/q/72837246/ asked by the user 'foseja' ( https://stackoverflow.com/u/13892944/ ) and on the answer https://stackoverflow.com/a/72843439/ provided by the user 'Tyler V' ( https://stackoverflow.com/u/9473786/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction

If you are developing an Android application that interacts with APIs, you might encounter various types of JSON responses. One common issue developers face is dealing with JSON responses that do not have a key. This situation often leads to confusion, especially with parsing libraries like Moshi. In this guide, we'll guide you through the process of handling a No Key JSON list response from the GitHub API and resolving a parsing error encountered in Moshi.

Understanding the Problem

The objective here is to retrieve a list of user repositories from the GitHub API. The expected JSON response is an array with several objects inside, each representing a repository. However, you may receive an error during parsing that states, Expected BEGIN_OBJECT but was BEGIN_ARRAY. This error indicates that Moshi is trying to parse a JSON array ([]) as if it were a JSON object ({}). To illustrate this, here's a sample of the JSON response you might receive:

[[See Video to Reveal this Text or Code Snippet]]

As shown in the response, it is an array that does not have a root key, leading to the confusion that results in the Moshi parsing error.

Solution

To resolve this issue, you need to ensure that your API interface method correctly reflects the structure of the JSON response. Let’s fix this error step by step.

Step 1: Modify Your API Call

Initially, your Retrofit API call is set up like this:

[[See Video to Reveal this Text or Code Snippet]]

Here, you are trying to return a UserRepoListResponse, which is intended for a specific object. Since the GitHub API returns a list, you should modify the return type to a list of UserRepoListResponseItem instead.

Update your method to:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Ensure Your Data Classes are Set Up Correctly

Your data classes should already be defined properly as follows:

[[See Video to Reveal this Text or Code Snippet]]

Make sure you have included all necessary fields that you need to parse the information from the JSON response correctly.

Step 3: Check Your Retrofit and Moshi Setup

Ensure that you have the necessary dependencies for Retrofit and Moshi included in your Gradle file:

[[See Video to Reveal this Text or Code Snippet]]

Configure Moshi and Retrofit like this:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By correctly returning a List<UserRepoListResponseItem> from your API call, you can resolve the Moshi error and successfully parse the No Key JSON response from the GitHub API. Following these steps will not only help you eliminate the parsing error but also enhance your understanding of how to handle different types of JSON responses effectively.

Stay tuned for more articles tackling common challenges faced by Android developers!