删除发送到Json MVC的对象的null属性

Question

namespace Booking.Areas.Golfy.Models
{
    public class Time
    {
        public string   time            { get; set; }
        public int      holes           { get; set; }
        public int      slots_available { get; set; }
        public decimal? price           { get; set; }
        public int?     Nextcourseid    { get; set; }

        public bool ShouldSerializeNextcourseid
        {
            get
            {
                return this.Nextcourseid != null;
            }
        }

        public bool? allow_extra { get; set; }

        public bool ShouldSerializeallow_extra
        {
            get
            {
                return this.allow_extra != null;
            }
        }
    }
}

namespace Booking.Areas.Golfy.Controllers
{
    public class TeetimesController : Controller
    {
        //
        // GET: /Golfy/Teetimes/
        public ActionResult Index(
            string date,
            int?   courseid = null,
            int?   clubid = null,
            int?   holes = null,
            int?   available = null,
            int?   prices = null
        )
        {
            var DateFrom = DateTime.ParseExact(date, "yyyy-MM-dd", CultureInfo.InvariantCulture);

            Teetimes r = BookingManager.GetBookings(new Code.Classes.Params.ParamGetBooking()
            {
                ClubID = clubid
                , DateFrom = DateFrom
                , DateTo = DateFrom.AddDays(1)
                , GroundID = courseid
            });

            return Json(r, JsonRequestBehavior.AllowGet);
        }
    }
}

上面的webservice返回一个json字符串,其中包含几个Time of Time.

我希望属性Nextcourseid和allow_extra在它们的值为null时被排除在输出之外.

我试过ShouldSerializeXxx,但它似乎不起作用.
仅供参考:我也试过[ScriptIgnore]哪个有效,但不是有条件的.

Answer 1

您不能使用默认值Json ActionResult删除null属性.

您可以查看JSON.NET,它有一个属性,您可以设置该属性,如果它为null,则删除该属性

[JsonProperty(NullValueHandling=NullValueHandling.Ignore)]

或者如果您不想使用其他库,您可以创建自己的json自定义ActionResult并为默认注册一个新的转换器JavaScriptSerializer,如下所示:

public class JsonWithoutNullPropertiesResult : ActionResult
{
    private object Data { get; set; }

    public JsonWithoutNullPropertiesResult(object data)
    {
        Data = data;
    }

    public override void ExecuteResult(ControllerContext context)
    {
        HttpResponseBase response = context.HttpContext.Response;
        response.ContentType = "application/x-javascript";
        response.ContentEncoding = Encoding.UTF8;

        if (Data != null)
        {
            JavaScriptSerializer serializer = new JavaScriptSerializer();
            serializer.RegisterConverters(new[] { new NullPropertiesConverter() });
            string ser = serializer.Serialize(Data);
            response.Write(ser);
        }
    }
}

public class NullPropertiesConverter : JavaScriptConverter
{
    public override IDictionary<string, object> Serialize(object obj, JavaScriptSerializer serializer)
    {
        var toSerialize = new Dictionary<string, object>();

        foreach (var prop in obj.GetType()
                                .GetProperties(BindingFlags.Instance | BindingFlags.Public)
                                .Select(p => new
                                {
                                    Name = p.Name,
                                    Value = p.GetValue(obj)
                                })
                                .Where(p => p.Value != null))
        {
            toSerialize.Add(prop.Name, prop.Value);
        }

        return toSerialize;
    }

    public override object Deserialize(IDictionary<string, object> dictionary, Type type, JavaScriptSerializer serializer)
    {
        throw new NotImplementedException();
    }

    public override IEnumerable<Type> SupportedTypes
    {
        get { return GetType().Assembly.GetTypes(); }
    }
}

现在在你看来:

public ActionResult Index()
{
    Teetimes r = BookingManager.GetBookings();
    return new JsonWithoutNullPropertiesResult(t);
}

Answer 2

我总是遇到框架嵌入的 json 序列化器的问题，因此我使用Json.NET。这是测试这两个序列化器的小示例：

public class Model {
    public int Id { get; set; }
    public string Name { get; set; }

    public bool ShouldSerializeName() {
        return Name != null;
    }
}

class Program {
    static void Main(string[] args) {
        var t1 = new Model {
            Name = "apw8u3rdmapw3urdm",
            Id = 298384
        };
        var t2 = new Model {
            Id = 234235
        };

        Test(t1);
        Test(t2);
    }

    static void Test(Model model) {
        Console.WriteLine("JSon from .Net: {0}", ToJson(model));
        Console.WriteLine("JSon from JSon.Net: {0}", ToDotNetJson(model));
    }

    static string ToJson(Model model) {
        var s = new JavaScriptSerializer();
        return s.Serialize(model);
    }

    static string ToDotNetJson(Model model) {
        return JsonConvert.SerializeObject(model);
    }
}

您必须System.Web.Extensions作为依赖项包含并Json.Net使用 nuget 安装才能使示例正常工作。

以下是Json.NET和框架嵌入式序列化程序的一些文档