Return json with lower case first letter of property names

Question

I have LoginModel:

public class LoginModel : IData
{
    public string Email { get; set; }
    public string Password { get; set; }
}

and I have the Web api method

public IHttpActionResult Login([FromBody] LoginModel model)
{
    return this.Ok(model);
}

And it's return 200 and body:

{
    Email: "dfdf",
    Password: "dsfsdf"
}

But I want to get with lower first letter in property like

{
    email: "dfdf",
    password: "dsfsdf"
}

And I have Json contract resolver for correcting

public class FirstLowerContractResolver : DefaultContractResolver
{
    protected override string ResolvePropertyName(string propertyName)
    {
        if (string.IsNullOrWhiteSpace(propertyName))
            return string.Empty;

        return $"{char.ToLower(propertyName[0])}{propertyName.Substring(1)}";
    }
}

How I can apply this?

Answer 1

To force all json data returned from api to camel case it's easier to use Newtonsoft Json with the default camel case contract resolver.

Create a class like this one:

using Newtonsoft.Json.Serialization;

internal class JsonContentNegotiator : IContentNegotiator
{
    private readonly JsonMediaTypeFormatter _jsonFormatter;

    public JsonContentNegotiator(JsonMediaTypeFormatter formatter)
    {
        _jsonFormatter = formatter;          
        _jsonFormatter.SerializerSettings.ContractResolver =
            new CamelCasePropertyNamesContractResolver();
    }

    public ContentNegotiationResult Negotiate(Type type, HttpRequestMessage request, IEnumerable<MediaTypeFormatter> formatters)
    {
        return new ContentNegotiationResult(_jsonFormatter, new MediaTypeHeaderValue("application/json"));
    }
}

and set this during api configuration (at startup):

var jsonFormatter = new JsonMediaTypeFormatter();
httpConfiguration.Services.Replace(typeof(IContentNegotiator), new JsonContentNegotiator(jsonFormatter));