JSON.Net Ignore Property during deserialization

Question

I have a class set up as follows:

public class Foo
{
    public string string1 { get; set; }
    public string string2 { get; set; }
    public string string3         


        

Answer 1

Here's the Newtonsoft Json preferred way to ignore a property without having to modify the class as based on http://james.newtonking.com/json/help/index.html?topic=html/ReducingSerializedJSONSize.htm

This one is used to ignore lazy reference properties of EF or Linq2Sql

public class DynamicContractResolver : DefaultContractResolver
{
    protected override IList<JsonProperty> CreateProperties(Type type, 
        MemberSerialization memberSerialization)
    {
        Func<Type,bool> includeProperty = t => t.IsValueType || t.Namespace.StartsWith("System") && t.Namespace.StartsWith("System.Data")==false; 
        IList<JsonProperty> properties = base.CreateProperties(type, memberSerialization);
        var allProperties = properties.Select (p => new{p.PropertyName,Including=includeProperty(p.PropertyType), p.PropertyType});//.Dump("props");
        var warnProperties=allProperties.Where (a =>a.Including && a.PropertyType.IsValueType==false && a.PropertyType.Name.IsIgnoreCaseMatch("String")==false) ;

        //linq pad debugging helper
        //var propertyTypesSerializing= allProperties.Where (p => p.Including).Select (p => p.PropertyType).Distinct().OrderBy (p => p.Name).Dump();

        if(warnProperties.Any())
        {
            //LinqPad helper
            //Util.Highlight(warnProperties.ToArray()).Dump("warning flag raised, aborting");
            throw new ArgumentOutOfRangeException();
        }

        properties = properties.Where(p =>includeProperty(p.PropertyType)).ToList();
        return properties;
    }
}

All the .Dump() calls are just linqpad debugging helpers, not needed method calls.

sample usage:

var inactives = from am in Aspnet_Memberships
        join mm in Member_members on am.UserId equals mm.Member_guid
        where mm.Is_active==false && mm.Org_id==1
        select new{am,mm};
        //inactives.Take(4).ToArray().Dump();
        var serialized = JsonConvert.SerializeObject(
            inactives.Skip(1).Select(i => i.mm).First(), 
            new  JsonSerializerSettings()
            {
                ContractResolver = new DynamicContractResolver(), 
                PreserveReferencesHandling = PreserveReferencesHandling.None,
                ReferenceLoopHandling= ReferenceLoopHandling.Ignore
            }); 
            //.Dump();

Answer 2

This is a lame workaround but you could make a method to manually load the json. If it's too much data to load without an automatic deserializer just remove the nodes that you don't want. This is a lot slower though.

public static List<Foo> FromJson(string input) {
    var json = JToken.Parse(input);
    json["key"].Remove();
    var foo = JsonConvert.DeserializeObject<List<Foo>>(json.ToString());

}

This is an interesting problem I wonder if anyone has a better solution for it.

Answer 3

You can use MissingMemberHandling property of the JsonSerializerSettings object.

Example usage:

var jsonSerializerSettings = new JsonSerializerSettings();
jsonSerializerSettings.MissingMemberHandling = MissingMemberHandling.Ignore;

JsonConvert.DeserializeObject<YourClass>(jsonResponse, jsonSerializerSettings);

More info here.

Answer 4

Alternative;

If ResponseAttribute has in model or string parameters

public class ResponseAttribute : Attribute { }

public class ModelItem
{
    [Response]
    public Guid Id { get; set; }
}

Code;

public class CustomJsonSerializer : JsonSerializerSettings
{
    public CustomJsonSerializer()
    {
        ContractResolver = new CustomContractResolver();
    }

    public CustomJsonSerializer(params string[] members)
    {
        ContractResolver = new CustomContractResolver(members);
    }

    public class CustomContractResolver : DefaultContractResolver
    {
        public string[] Members { get; set; }
        public CustomContractResolver(params string[] _members)
        {
            Members = _members;
        }

        protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
        {
            JsonProperty property = base.CreateProperty(member, memberSerialization);

            if (Members?.Length > 0)
                property.ShouldSerialize = instance => { return Members.Contains(member.Name); };
            else
                property.ShouldSerialize = instance => { return member.GetCustomAttribute<ResponseAttribute>() != null; };

            return property;
        }
    }
}

Use;

return new JsonResult(model, new CustomJsonSerializer());

or

return new JsonResult(model, new CustomJsonSerializer("Id","Test","Test2"));

Answer 5

Adding to drzaus answer: You can use the DefaultContractResolver he suggested .. just in its CreateProperty use property.Ignored = true; instead of property.ShouldSerialize, then its good either when you pass the JsonSerializerSettings to the DeserializeObject function or the SerializeObject function.

Answer 6

Similar to @Maslow's solution, you can use another general purpose "ignorer":

var jsonResolver = new IgnorableSerializerContractResolver();
// ignore your specific property
jsonResolver.Ignore(typeof(Foo), "string2");
// ignore single datatype
jsonResolver.Ignore(typeof(System.Data.Objects.DataClasses.EntityObject));
var jsonSettings = new JsonSerializerSettings() { ReferenceLoopHandling = ReferenceLoopHandling.Ignore, ContractResolver = jsonResolver };