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?

Will this work? http://tostring.it/2012/07/18/customize-json-result-in-web-api/ — Murray Foxcroft, Apr 27 '16 at 08:38

score 40 · Answer 1 · answered Apr 27 '16 at 08:37

If your are using Newtonsoft.Json, you can add JsonProperties to your view model :

public class LoginModel : IData
{
     [JsonProperty(PropertyName = "email")]
     public string Email {get;set;}

     [JsonProperty(PropertyName = "password")]
     public string Password {get;set;}
}

Luca Ghersi · Accepted Answer · 2016-04-27T08:43:48.307

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));

This works very well even with Entity Framework in a WebAPI project. Just place the startup code provided here in the `WebApiConfig` class (replace `httpConfiguration` with `config`). — SiZiOUS, Apr 25 '18 at 13:00
There is only one issue, all the json fields, also the ones not related to the viewmodel, are going to be lower cased. The other issue is that it does not work with nested properties/objects ie: myTopKey.MySubKey --should be---> myTopKey.mySubKey — Carlo Luther, Sep 06 '18 at 16:07

Hakan Fıstık · Answer 3 · 2020-11-11T18:37:46.197

13

You can add the two following statement in the configuration of the web API or to the startup file

using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;

GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver();
GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.Formatting = Formatting.Indented;

But it is very important to use the return Ok() method instead of return Json() otherwise; this will not work.

if you have to use Json method (and have no other choice) then see this answer https://stackoverflow.com/a/28960505/4390133

edited Nov 11 '20 at 18:37

answered Nov 21 '17 at 09:39

Hakan Fıstık

16,800
14
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131

1

So much better than accepted answer! But, I am only going to use CamelCasePropertyNamesContractResolver; not Formatting.Indented – steve Dec 28 '19 at 05:06
1

This answer is better than others. Setting up the configuration in the startup is a much better way to solve this issue. – mavi Mar 24 '21 at 16:30
Where does this go in Startup.cs? – Derek R Mar 07 '22 at 17:31
@DerekR yes in startup.cs – Hakan Fıstık Mar 08 '22 at 08:17

Grengas · Answer 4 · 2023-06-20T08:56:57.853

If you need it only in some certain place and not throughout whole application, then you can do following:

var objectToSerialize = new {Property1 = "value1", SubOjbect = new { SubObjectId = 1 }};
var json = Newtonsoft.Json.JsonConvert.SerializeObject(data, new JsonSerializerSettings { ContractResolver = new Newtonsoft.Json.Serialization.CamelCasePropertyNamesContractResolver() });

It should result in {"property1":"value1","subOjbect":{"subObjectId":1}} (note that nested properties also start from lowercase)

Return json with lower case first letter of property names

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