C# – How to read problem details JSON with HttpClient

Problem details (RFC7807) is a standardized error response format that has a Content-Type of application/problem+json, an error response code (i.e. 400 – Bad Request), and has a response body that looks like this: This can be extended to include any number of properties. The example shown above comes from the default way ASP.NET Core returns … Read more

C# – Deserialize JSON using different property names

When JSON property names and class property names are different, and you can’t just change the names to match, you have three options: Use the JsonPropertyName attribute. Use a naming policy (built-in or custom). A combination of these two. In other words, use JsonPropertyName for special cases that your naming policy doesn’t handle. These affect … Read more

C# – Deserialize JSON with a specific constructor

When your class has multiple constructors, you can use the JsonConstructor attribute to specify which constructor to use during deserialization. Here’s an example: Note: JsonConstructor for System.Text.Json was added in .NET 5. Now deserialize: This outputs: This shows that it used the Person(int luckyNumber) constructor. It passed in the LuckyNumber JSON property to the constructor, … Read more

C# – Deserialize JSON to a derived type

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# – Populate an existing object with JSON

Normally when you’re working with JSON, you deserialize it to a target type and get back an initialized and fully populated object. How about if you need to initialize an object yourself, and then populate it with JSON later? For example, let’s say you want to load the following JSON array into a case-insensitive HashSet: … Read more

C# – How to ignore JSON deserialization errors

One error during deserialization can cause the whole process to fail. Consider the following JSON. The second object has invalid data (can’t convert string to int), which will result in deserialization failing: With Newtonsoft, you can choose to ignore deserialization errors. To do that, pass in an error handling lambda in the settings: This outputs … Read more

C# – Deserialize a JSON array to a list

When you’re working with a JSON array, you can deserialize it to a list like this: This deserializes all of the objects in the JSON array into a List<Movie>. You can use this list object like usual. Note: All examples will use System.Collections.Generic and System.Text.Json. I’ll exclude the using statements for brevity. Example – JSON … Read more

C# – Deserialize JSON as a stream

Here’s an example of deserializing a JSON file as a stream with System.Text.Json: Stream deserialization has three main benefits: It’s memory-efficient, which improves overall performance. Fail fast when there’s a problem in the JSON data. Deserialization process can be canceled (async version only). In this article, I’ll go into details about these benefits and show … Read more

C# – Changing the JSON serialization date format

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 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 converter and pass it in: Here’s the custom … Read more

C# – Convert an object to JSON and vice versa

The simplest way to convert an object to JSON (serialization) is to use the built-in System.Text.Json.JsonSerializer: This serializes the Movie object to JSON using the default serialization settings (notice it’s not pretty printed by defualt). Here’s the JSON this produces: To do the opposite – convert a JSON string to an object (deserialization) – use … Read more