Json.net serialize only certain properties

Question

Does Json.net have any way to specify only the properties you want to be serialized? or alternatively serialize certain properties based on binding flags like Declared Only?

Right now I am using JObject.FromObject(MainObj.SubObj); to get all properties of SubObj which is an instance of a class that obeys the ISubObject interface:

public interface ISubObject
{

}

public class ParentSubObject : ISubObject
{
    public string A { get; set; }
}


public class SubObjectWithOnlyDeclared : ParentSubObject
{
    [JsonInclude] // This is fake, but what I am wishing existed
    public string B { get; set; }

    [JsonInclude] // This is fake, but what I am wishing existed
    public string C { get; set; }
}

public class NormalSubObject: ParentSubObject
{
    public string B { get; set; }
}

If MainObj.SubObj was a NormalSubObject it would serailize both A and B but if it was SubObjectWithOnlyDeclared it would serailize only B and C and ignore the parent property

Checkout this article on conditional serialization. I found it useful. https://www.geekytidbits.com/conditional-serialization-with-json-net/ — Rich, Jun 21 '18 at 18:33

score 50 · Answer 1 · answered Mar 07 '19 at 14:31

Rather then having to use [JsonIgnore] on every attribtue you don't want to serialise as suggested in another answer.

If you just want to specify properties to serialise, you can do this, using [JsonObject(MemberSerialization.OptIn)] and [JsonProperty] attributes, like so:

using Newtonsoft.Json;
...
[JsonObject(MemberSerialization.OptIn)]
public class Class1
{
    [JsonProperty]
    public string Property1 { set; get; }
    public string Property2 { set; get; }
}

Here only Property1 would be serialised.

This should be the selected answer – JKennedy Mar 24 '21 at 14:54 — JKennedy, Mar 24 '21 at 14:54

Eser · Accepted Answer · 2018-06-21T19:21:21.287

You can write a custom ContractResolver like below

public class IgnoreParentPropertiesResolver : DefaultContractResolver
{
    bool IgnoreBase = false;
    public IgnoreParentPropertiesResolver(bool ignoreBase)
    {
        IgnoreBase = ignoreBase;
    }
    protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
    {
        var allProps = base.CreateProperties(type, memberSerialization);
        if (!IgnoreBase) return allProps;

        //Choose the properties you want to serialize/deserialize
        var props = type.GetProperties(~BindingFlags.FlattenHierarchy); 

        return allProps.Where(p => props.Any(a => a.Name == p.PropertyName)).ToList();
    }
}

Now you can use it in your serialization process as:

var settings = new JsonSerializerSettings() { 
                      ContractResolver = new IgnoreParentPropertiesResolver(true) 
               };
var json1 = JsonConvert.SerializeObject(new SubObjectWithOnlyDeclared(),settings );

Thank you, exactly what i was looking for – papfan Sep 12 '18 at 17:49 — papfan, Sep 12 '18 at 17:49

score 3 · Answer 3 · answered Jun 21 '18 at 18:03

3

Not sure why @Eser chose to write the answer as comment to your question as opposed to an actual answer... anyway, they're correct.

Apply the [JsonIgnore] attribute to any property that you want to ignore.

answered Jun 21 '18 at 18:03

Aydin

15,016
4
32
42

2

This isnt an acceptable answer though, I would need to conditionally ignore `public string A { get; set; }` because in one scenario I dont want it ignored, and in another I do. – CuriousDeveloper Jun 21 '18 at 18:15

Atif Rehman · Answer 4 · 2020-06-19T19:14:49.043

3

If you have a property on your object that is null or the default value, you can let json.net ignore it and NOT serialize it by:

var settings = new JsonSerializerSettings 
{
    DefaultValueHandling = DefaultValueHandling.Ignore, NullValueHandling = NullValueHandling.Ignore
};

JsonConvert.SerializeObject(myObject, settings);

EDIT:

Or global default setting, do this once:

JsonConvert.DefaultSettings = () => new JsonSerializerSettings 
{
    DefaultValueHandling = DefaultValueHandling.Ignore, NullValueHandling = NullValueHandling.Ignore
};

edited Jun 19 '20 at 19:14

answered Jun 19 '20 at 19:00

Atif Rehman

417
6
6

thanks a lot.. this is what I was looking fore – sabsab Dec 27 '21 at 00:42

Json.net serialize only certain properties

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