I've just declared a constant for the "application/json" content type in one of my classes.
public const string JsonContentType = "application/json";
I'm not sure it is a good practice.
Does .NET framework have a predefined const for "application/json"?
In order to add an up-to-date answer: since dotnet core 2.1 MediaTypeNames.Application.Json
has been defined.
See https://github.com/dotnet/corefx/pull/26701 for the changeset.