Solving the RuntimeBinderException with System.Text.Json.Serialize and Dynamic Types

Learn how to fix the `RuntimeBinderException` when using `System.Text.Json.Serialize` with dynamic types in C# . This guide provides a clear solution and explains why avoiding dynamic typing can save you headaches.
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Tackling RuntimeBinderException with System.Text.Json.Serialize

Developers frequently turn to System.Text.Json for JSON serialization in C# , thanks to its efficiency and straightforward usage. However, occasional hiccups can arise, particularly with dynamic types. A common issue is encountering a RuntimeBinderException, but fear not! This guide will walk you through understanding and solving this problem step-by-step.

The Problem: What is RuntimeBinderException?

Recently, a developer faced the following error when attempting to serialize a dynamic object:

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

This error surfaced only in Release mode, leaving the developer puzzled since the code worked perfectly in Debug mode. It indicated that the Serialize() method couldn't find a suitable overload when parsedJson, of type dynamic, was null.

Key Takeaway

The crux of the issue lies in the ambiguity created by dynamic typing when the object is null. This can lead to confusion in method resolution, particularly with the rich overloads available in System.Text.Json.

The Solution: Avoid Using Dynamic Types

Instead of relying on dynamic, which adds unnecessary complexity in this scenario, you can simply use object. This change prevents ambiguity and ensures that serialization runs smoothly—even when dealing with null values.

Here’s How to Fix It

Replace your original PrettifyJson method with the following implementation:

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

Why This Works

Clarity in Type: By using object, the ambiguity that comes with dynamic types is eliminated.

Handling null: When passing a null string as input, the method can still process it effectively without throwing an exception. In this case, JsonSerializer.Serialize<object>(null, optionPrettyPrint) simply returns the string "null".

Consistency Across Modes: This updated method should work seamlessly in both Debug and Release modes, allowing for consistent behavior during development and deployment.

Conclusion

In summary, the RuntimeBinderException when using dynamic types with System.Text.Json.Serialize can be frustrating, especially when it only appears in certain scenarios. However, by replacing dynamic with object, you can resolve the ambiguity and ensure smooth serialization. Adopting this simple change not only solves the issue at hand but also fosters cleaner and more maintainable code.

Remember: when dealing with serialization in C# , clarity in types often trumps convenience.

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