How to Customize Object Serialization to JSON in C# for ASP.NET Core Web API

Discover how to customize your object serialization to JSON in C# for ASP.NET Core Web API, ensuring your data is returned in a format that suits your needs.
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How to Customize Object Serialization to JSON in C# for ASP.NET Core Web API

When developing an ASP.NET Core Web API, you might encounter scenarios where the default JSON serialization doesn't meet your requirements. For instance, you may want to return a list of objects in a specific format rather than the generic one provided by default. In this guide, we will explore how to achieve that by customizing object serialization in C# .

The Problem

Let's say you have a class called obj which is defined as follows:

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

When you serialize a list of this object and return it in your API, the default JSON output will look something like this:

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

However, your desired structure is a bit different. You want the output to map the schoolName to a new nested object that contains studentscount and teacherscount. This means your preferred format should look like this:

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

The Solution

To achieve this customized serialization, we can utilize a combination of a new class and the powerful Newtonsoft.Json library to manipulate the output before sending it back. Below, we will break down the process into clear steps.

Step 1: Create a New Class

Create a new class called Counts that will hold the studentscount and teacherscount. This will facilitate our transformation of the initial data structure:

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

Step 2: Transform the JSON Data

Now, we can write code to transform the initial JSON array into the desired dictionary format using LINQ:

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

This code snippet does the following:

Parses the existing JSON into a JArray,

Transforms it into a dictionary where each key is the schoolName, and the value is an instance of the Counts class containing the counts of students and teachers.

Step 3: Serialize Custom Format

Once we have our dictionary set up, we can serialize it to JSON with readable formatting:

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

Resulting Output

The resulting output from this process will match your desired format:

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

Step 4: Returning as an Array (Optional)

If you still require the output to be in an array format, you can wrap the counts dictionary in a list:

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

Final Output Example

The final output would look like this, satisfying the requirement for an array encapsulation:

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

Conclusion

Customizing JSON serialization in ASP.NET Core Web API can seem challenging, but with the right approach and tools like Newtonsoft.Json, you can achieve your desired output format effortlessly. By following the steps outlined in this guide, you can ensure that your Web API returns data in a way that meets your application's specific requirements.

Feel free to reach out if you have any further questions or need assistance with your API development!