add support for newtonsoft.json

[devlux]

add support for Newtonsoft.Json by providing a new newtonsoft specific saunter package.

[m-wild]

While this reflects the behaviour of Newtonsoft.Json, it does not reflect the behaviour of System.Text.Json.

void Main()
{
	Newtonsoft.Json.JsonConvert.SerializeObject(new Example(), new JsonSerializerSettings
		{
			Formatting = Newtonsoft.Json.Formatting.Indented,
			ContractResolver = new CamelCasePropertyNamesContractResolver()
		})
		.Dump();
	// {
	//    "someOtherName": null
	// }
	
	System.Text.Json.JsonSerializer.Serialize(new Example(), new JsonSerializerOptions
		{
			WriteIndented = true,
			PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
		})
		.Dump();
	// {
	//    "SomeOtherName": null
	// }
}

class Example
{
	[JsonProperty("SomeOtherName")]
	[JsonPropertyName("SomeOtherName")]
	public string FooBar { get; set; }
}

Since we are now using System.Text.Json as our serializer (as is the default for new dotnet projects), I feel it makes sense to keep this behaviour as-is.

Additionally, we should remove the current DataMember check as this does not match System.Text.Json behaviour either.

Someone using Newtonsoft.Json will need to provide a custom PropertyNameSelector which matches their Newtonsoft.Json settings.

options.PropertyNameSelector = prop => 
{
    var name = prop.GetCustomAttribute<JsonPropertyAttribute>()?.PropertyName
        ?? prop.GetCustomAttribute<DataMemberAttribute>()?.Name
        ?? prop.Name;
    return new CamelCaseNamingStrategy().GetPropertyName(name, false);
}

---

I think the better option here would be to provide a Newtonsoft.Json compatibility library.
This would be a 2nd, optional, Nuget package, which provides an extension method for enabling Newtonsoft.Json support.

$ dotnet add package Saunter
$ dotnet add package Saunter.NewtonsoftJson

Startup.cs

services.AddAsyncApiSchemaGeneration(options =>
{
    options.UseNewtonsoftJson();
});

This UseNewtonsoftJson() method could set a default PropertyNameSelector which mimics Newtonsoft.Json behaviour (checking [Newtonsoft.Json.JsonPropertyAttribute] and [DataMemberAttribute])

Though, given this entire library would be just the ~4 lines of code, maybe just providing documentation would be better!

[devlux]

Good point, I didn't know this difference. If this is the case, then your comment makes absolutely sense. Even though I find the system.text.json strategy to be quite strange as you could end up with an inconsistent naming. But as long as they stick with this weird solution, it makes sense to be inline. ;-)

[neoaisac]

I've proposed in #89 that the serialization logic is extracted into a separate type. Developers can then use this to provide their own serializing logic, and it could potentially be used to create different adapters for this, including Newtonsoft.Json or Yaml.

[m-wild]

Closing in favor of #60