How to Ignoring Fields and Properties Conditionally During Serialization Using JSON.Net?

Question

How to Ignoring Fields and Properties Conditionally During Serialization Using JSON.Net? I can't inherit from JsonIgnoreAttribute because it's a sealed class. What should I do?

Did you check [ScriptIgnore](http://stackoverflow.com/questions/10169648/how-to-exclude-property-from-json-serialization) ? — Kurubaran, Dec 16 '15 at 05:46
@Kurubaran yes but I want to Ignoring a Field Conditionally.. — Mohamad Shiralizadeh, Dec 16 '15 at 05:52

score 18 · Answer 1 · answered Dec 16 '15 at 05:53

18

You can use JSON.NET's ShouldSerialize-syntax. There's a good example on JSON.NET site:

http://www.newtonsoft.com/json/help/html/ConditionalProperties.htm

public class Employee
{
    public string Name { get; set; }
    public Employee Manager { get; set; }

    public bool ShouldSerializeManager()
    {
        // don't serialize the Manager property if an employee is their own manager
        return (Manager != this);
    }
}

If ShouldSerialize doesn't fit your needs, you can take full control of the serialization with the ContractResolvers: http://www.newtonsoft.com/json/help/html/ContractResolver.htm

answered Dec 16 '15 at 05:53

Mikael Koskinen

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Never had any luck getting this to work, breakpoints show that this is never even called during serialization. – Wobbles Apr 07 '16 at 23:01
Note that the ShouldSerialize-syntax is a convention such that for property Foo, you'd have a ShouldSerializeFoo() method, which would return a true or false as to whether Foo should be serialized. – CharlieNoTomatoes May 30 '17 at 19:54

score 2 · Accepted Answer · answered Dec 16 '15 at 07:21

I found the answer. I inherit from JsonConverter and create a new convertor.

public class CustomJsonConverter : JsonConverter
{
    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        var list = (IList)value;

        JArray s = new JArray();

        foreach (var item in list)
        {
            JToken token = JToken.FromObject(item);
            JObject obj = new JObject();

            foreach (JProperty prop in token)
            {
                if (prop.Name != "Title") // your logic here
                    obj.Add(prop);
            }

            s.Add(obj);
        }

        s.WriteTo(writer);

    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        throw new NotImplementedException("Unnecessary because CanRead is false. The type will skip the converter.");
    }

    public override bool CanRead
    {
        get { return false; }
    }

    public override bool CanConvert(Type objectType)
    {
        return objectType != typeof(IList);
    }
}

How to Ignoring Fields and Properties Conditionally During Serialization Using JSON.Net?

2 Answers2

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