How to Deserialize a JSON Array with Nulls to a List int in C# Using JSON.NET

Learn how to effectively handle deserialization of JSON arrays containing null values into a non-nullable `int` list using custom converters in JSON.NET.
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How to Deserialize a JSON Array with Nulls to a List<int> in C- Using JSON.NET

Working with JSON in C- can sometimes lead to unexpected challenges, especially when dealing with null or empty values. A common issue developers encounter is deserializing a JSON array that contains blank entries into a non-nullable int list. If you've found yourself facing this particular challenge, you're in the right place! In this guide, we'll explore how to effectively handle the deserialization of a JSON array with nulls or empty strings into a list of integers using JSON.NET.

Understanding the Problem

You may have a JSON structure that looks similar to this:

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

In your C- class, you wish to deserialize this into a property defined as follows:

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

However, attempting to deserialize the above JSON into this List<int> will result in an error due to the presence of empty string values. The error message indicates that it can't convert a null or empty string to a value type (System.Int32).

Error Encountered

When trying to deserialize, you might encounter the following error:

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

This happens because the JSON deserializer does not know how to convert an empty string into an integer. By default, it expects all string values in the array to be convertible.

The Solution: Custom JsonConverter

To handle this deserialization challenge, we can create a custom JsonConverter that will process each item in the JSON array. The converter will ignore nulls and empty strings, converting only valid string representations of integers into their corresponding integers.

Step 1: Create the Custom Converter

Here’s how you can create a custom converter named NullableStringToIntConverter:

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

Step 2: Apply the Custom Converter

Now, apply this converter to your class definition for the property you want to deserialize:

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

Step 3: Deserialize the JSON

Finally, you can deserialize your JSON string into your Thing object as follows:

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

This will successfully convert the edges JSON array into a non-nullable list of integers, filtering out any empty or null entries.

Conclusion

Handling JSON deserialization in C-, particularly with nullable values, doesn't have to be a hassle. By utilizing a custom JsonConverter, you can effectively transform JSON arrays with empty strings or nulls into clean, usable data structures like a List<int>. This approach allows you to maintain strong typing in your data models without compromising on data integrity.

If you encounter similar challenges in your programming journey, remember this method to customize your deserialization process effectively!