jsonconverter

C# – Serialize and deserialize a multidimensional array to JSON

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System.Text.Json doesn’t support serializing / deserializing multidimensional arrays. When you try, it throws an exception like this – System.NotSupportedException: The type ‘System.Int[,] is not supported. You have three options: In this article, I’ll show an example of how to create a custom JsonConverter that handles multidimensional arrays. In this example, I’ll specifically show how to … Read more

C# – Deserialize JSON with a specific constructor

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When your class has multiple constructors, you can use the JsonConstructor attribute to specify which constructor to use during deserialization. Here’s an example. The Person class has two constructors. I put the JsonConstructor attribute on one of the constructors: Note: JsonConstructor for System.Text.Json was added in .NET 5. Now deserialize a JSON string to the … Read more

C# – Deserialize JSON to a derived type

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The simplest way to deserialize JSON to a derived type is to put the type name in the JSON string. Then during deserialization, match the type name property against a set of known derived types and deserialize to the target type. System.Text.Json doesn’t have this functionality out of the box. That’s because there’s a known … Read more

C# – How to use JsonConverterAttribute

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You can use JsonConverterAttribute (from System.Text.Json) to apply a specific JsonConverter to a property. Apply this attribute on a property and specify the JsonConverter type to use, like this: In this example, it’s applying ExpirationDateConverter (a custom JSON converter) to handle the ExpirationDate. For reference, here’s ExpirationDateConverter’s definition: Now serialize the object to JSON: Here’s … Read more

C# – Changing the JSON serialization date format

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When you serialize a date with System.Text.Json, it uses the standard ISO-8601 date format (ex: “2022-01-31T13:15:05.2151663-05:00”). Internally, it uses the built-in DateTimeConverter class for handling DateTime, which doesn’t give you a way to change the date format. To change the date format, you have to create a custom JSON converter and pass it in: This … Read more

C# – Deserializing JSON with quoted numbers

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There are two ways to represent numbers in JSON: as number literals (ex: 123) or as quoted numbers (ex: “123”). In this article, I’ll explain how quoted numbers are handled during deserialization in Newtonsoft and System.Text.Json and how to change the behavior. At the end, I’ll show how to write quoted numbers during serialization. Quoted … Read more