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# – 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# – 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

C# – Deserializing JSON with quoted numbers

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

C# – How to update appsettings.json programmatically

You have to overwrite the appsettings.json file to be able to update values programmatically. You have to deal with the whole file, not individual parts of it. The process can be summarized in the following steps: Load appsettings.json and deserialize it into an object. Update properties on the object. Serialize the object into a JSON … Read more

C# – Newtonsoft extension methods for HttpClient

System.Net.Http.Json provides extension methods that simplify getting and sending JSON with HttpClient. Internally, it uses System.Text.Json for serialization. What if you want to use Newtonsoft instead of System.Text.Json? You can use the following extension methods for that: These are modeled off of the extension methods in System.Net.Http.Json. You can pass in a JsonSerializerSettings object to … Read more

C# – Get and send JSON with HttpClient

The simplest way to get and send JSON with HttpClient is to use the GetFromJsonAsync() and PostAsJsonAsync() extension methods found in System.Net.Http.Json, like this: Note: You have to install the System.Net.Http.Json nuget package if you’re using a framework version before .NET 5. These extension methods use System.Text.Json for serialization. They simplify things by abstracting away … Read more