CODEWITHSUNDEEP
c#serializationattributesjson.net
CuriousDeveloper
CuriousDeveloper

Reputation: 899

Json.net serialize only certain properties

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

Upvotes: 20

Views: 35249

Answers (4)

Atif Rehman
Atif Rehman

Reputation: 467

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
};

Upvotes: 3

Alfie
Alfie

Reputation: 2013

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.

Upvotes: 56

Eser
Eser

Reputation: 12546

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 );

Upvotes: 17

Aydin
Aydin

Reputation: 15324

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.

Upvotes: 2

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