Building a Recipe Planning App with Kotlin and Edamam API

This tutorial will guide you through the process of building a Recipe Planning App using Kotlin and the Edamam API. We will cover everything from setting up the project to implementing search functionality and displaying recipe details. By the end of this tutorial, you will have a fully functional Recipe Planning App that allows users to search for recipes, view recipe details, and save their favorite recipes.

Introduction

What is a Recipe Planning App?

A Recipe Planning App allows users to search for recipes based on their preferences and plan their meals accordingly. It provides a convenient way to discover new recipes, organize them into categories, and create meal plans for the week. With the help of the Edamam API, we can fetch a wide variety of recipes and display them in our app.

Benefits of Using Kotlin for App Development

Kotlin is a modern programming language that is fully compatible with Java. It offers many advantages over Java, such as null safety, extension functions, and coroutines. Kotlin is also concise and expressive, which makes it easier to read and write code. Additionally, Kotlin has excellent support for Android development, making it the perfect choice for building Android apps.

Overview of Edamam API

The Edamam API is a powerful tool for retrieving recipe data. It provides endpoints for searching recipes, retrieving recipe details, and more. To use the Edamam API, you will need to sign up for an API key, which you can obtain from the Edamam website. The API key allows you to make authenticated requests to the API and access the recipe data.

Setting Up the Project

Creating a New Kotlin Project

To start, create a new Kotlin project in Android Studio. Choose a project name and package name that suits your needs. Once the project is created, you will have a basic project structure with the necessary files for building an Android app.

Adding Dependencies

To use the Edamam API in our app, we need to add the necessary dependencies to our project. Open the build.gradle file of your app module and add the following dependencies:

dependencies {
    implementation 'com.squareup.retrofit2:retrofit:2.9.0'
    implementation 'com.squareup.retrofit2:converter-gson:2.9.0'
}

These dependencies allow us to make HTTP requests and convert JSON responses into Kotlin objects using Retrofit and Gson.

Configuring API Key

Next, we need to configure our API key. Create a new file called api.properties in the root directory of your project. Add the following line to the file:

API_KEY=your_api_key_here

Replace your_api_key_here with your actual API key from Edamam. Then, open the build.gradle file of your app module again and add the following code at the bottom:

android {
    // ...

    defaultConfig {
        // ...
        buildConfigField("String", "API_KEY", "\"${getProperty('API_KEY')}\"")
    }
}

This code reads the API key from the api.properties file and injects it into the generated BuildConfig class of your app.

Designing the User Interface

Creating Layouts

To create a visually appealing and user-friendly app, we need to design our user interface. Start by creating the necessary layout XML files for the different screens of our app. For example, we can create a activity_main.xml file for the main screen and a activity_recipe_detail.xml file for the recipe detail screen. Use the layout editor in Android Studio to design the layout of each screen.

Implementing Navigation

Next, we need to implement navigation between the different screens of our app. We can use the Navigation component provided by Android Jetpack to handle navigation. Define a navigation graph XML file that contains all the destinations and actions of our app. Then, add a NavHostFragment to the main activity layout file to host the navigation graph.

Handling User Input

To allow users to search for recipes, we need to add a search input field to our main screen layout. Use an EditText or a SearchView widget to capture user input. Implement a listener to detect when the user submits the search query. In the listener, we can make an API request to retrieve the recipes based on the user's input.

Fetching Recipe Data

Making API Requests

To retrieve recipe data from the Edamam API, we need to make HTTP requests. We can use Retrofit, a type-safe HTTP client for Android, to simplify the process. First, create an interface that defines the API endpoints and the corresponding request methods. Use annotations to specify the HTTP method, path, and query parameters. Then, create an instance of the Retrofit client and configure it with the base URL of the API and a Gson converter factory.

Parsing JSON Responses

When we receive a response from the API, it will be in JSON format. We need to parse the JSON data into Kotlin objects to work with them in our app. Retrofit can automatically convert the JSON response into Kotlin objects using Gson. Define data classes that correspond to the structure of the JSON response. Use annotations to map the JSON keys to the class properties. Retrofit will handle the conversion for us.

Handling Errors

Sometimes, API requests can fail due to various reasons, such as network issues or invalid input. We need to handle these errors gracefully in our app. Retrofit provides a way to define a custom error response converter that converts error responses into Kotlin objects. Use this converter to handle different types of errors, such as authentication errors or server errors. Display appropriate error messages to the user.

Displaying Recipe Details

Creating Recipe Detail Activity

To display recipe details, we need to create a new activity that shows the details of a selected recipe. Create a new layout XML file for the recipe detail screen and design it according to your preferences. In the activity code, retrieve the recipe data from the intent extras and populate the views with the data. Add any additional functionality, such as saving the recipe as a favorite.

Populating Data

To populate the recipe detail views with data, we need to pass the recipe data from the previous screen to the recipe detail activity. When the user selects a recipe from the search results, create an intent and add the recipe data as extras. Start the recipe detail activity with the intent. In the recipe detail activity, retrieve the recipe data from the intent extras and display it in the appropriate views.

Adding Favorite Functionality

To allow users to save their favorite recipes, we can add a favorite button to the recipe detail screen. When the user clicks the button, save the recipe data to a local database or shared preferences. Use a database library like Room or a key-value store like SharedPreferences to store and retrieve the favorite recipes. Update the UI accordingly to indicate whether a recipe is saved as a favorite.

Implementing Recipe Search

Creating Search Functionality

To implement recipe search, we need to capture the user's search query and make an API request to retrieve the matching recipes. In the search input listener, extract the search query and pass it to the API request method. Make the API request using Retrofit and handle the response asynchronously. Display the search results in a RecyclerView or a ListView.

Filtering and Sorting Results

To enhance the search functionality, we can add filtering and sorting options to the app. Allow users to filter recipes based on dietary restrictions, cuisine types, or ingredient preferences. Implement a filtering mechanism that applies the selected filters to the search results. Additionally, provide sorting options such as relevance, rating, or preparation time. Sort the search results accordingly to improve usability.

Pagination

If the API returns a large number of search results, it may be necessary to implement pagination to load the results in chunks. Implement a mechanism to load more results when the user reaches the end of the current list. Make additional API requests with different page numbers to retrieve the next set of results. Append the new results to the existing list and update the UI accordingly.

Conclusion

In this tutorial, we have built a Recipe Planning App using Kotlin and the Edamam API. We have covered everything from setting up the project to implementing search functionality and displaying recipe details. By following this tutorial, you have learned how to make API requests, parse JSON responses, handle errors, and create a user-friendly interface. With the knowledge gained from this tutorial, you can further enhance the app by adding more features and improving the user experience. Happy coding!