How to exclude property from Json Serialization

Question

I have a DTO class which I Serialize

Json.Serialize(MyClass)

How can I exclude a public property of it?

(It has to

Answer 1

If you are not so keen on having to decorate code with Attributes as I am, esp when you cant tell at compile time what will happen here is my solution.

Using the Javascript Serializer

    public static class JsonSerializerExtensions
    {
        public static string ToJsonString(this object target,bool ignoreNulls = true)
        {
            var javaScriptSerializer = new JavaScriptSerializer();
            if(ignoreNulls)
            {
                javaScriptSerializer.RegisterConverters(new[] { new PropertyExclusionConverter(target.GetType(), true) });
            }
            return javaScriptSerializer.Serialize(target);
        }

        public static string ToJsonString(this object target, Dictionary> ignore, bool ignoreNulls = true)
        {
            var javaScriptSerializer = new JavaScriptSerializer();
            foreach (var key in ignore.Keys)
            {
                javaScriptSerializer.RegisterConverters(new[] { new PropertyExclusionConverter(key, ignore[key], ignoreNulls) });
            }
            return javaScriptSerializer.Serialize(target);
        }
    }


public class PropertyExclusionConverter : JavaScriptConverter
    {
        private readonly List propertiesToIgnore;
        private readonly Type type;
        private readonly bool ignoreNulls;

        public PropertyExclusionConverter(Type type, List propertiesToIgnore, bool ignoreNulls)
        {
            this.ignoreNulls = ignoreNulls;
            this.type = type;
            this.propertiesToIgnore = propertiesToIgnore ?? new List();
        }

        public PropertyExclusionConverter(Type type, bool ignoreNulls)
            : this(type, null, ignoreNulls){}

        public override IEnumerable SupportedTypes
        {
            get { return new ReadOnlyCollection(new List(new[] { this.type })); }
        }

        public override IDictionary Serialize(object obj, JavaScriptSerializer serializer)
        {
            var result = new Dictionary();
            if (obj == null)
            {
                return result;
            }
            var properties = obj.GetType().GetProperties();
            foreach (var propertyInfo in properties)
            {
                if (!this.propertiesToIgnore.Contains(propertyInfo.Name))
                {
                    if(this.ignoreNulls && propertyInfo.GetValue(obj, null) == null)
                    {
                         continue;
                    }
                    result.Add(propertyInfo.Name, propertyInfo.GetValue(obj, null));
                }
            }
            return result;
        }

        public override object Deserialize(IDictionary dictionary, Type type, JavaScriptSerializer serializer)
        {
            throw new NotImplementedException(); //Converter is currently only used for ignoring properties on serialization
        }
    }