Newtonsoft Add JSONignore at Runtime

NewtonSoft add JSONIGNORE at runTime

No need to do the complicated stuff explained in the other answer.

NewtonSoft JSON has a built-in feature for that:

public bool ShouldSerializeINSERT_YOUR_PROPERTY_NAME_HERE()
{
    if(someCondition){
        return true;
    }else{
        return false;
    }
}

It is called "conditional property serialization" and the documentation can be found here.

Warning: first of all, it is important to get rid of [JsonIgnore] above your {get;set;} property. Otherwise it will overwrite the ShouldSerializeXYZ behavior.

Can I optionally turn off the JsonIgnore attribute at runtime?

Yes, this can be done using a custom ContractResolver.

You didn't show any code, so I'll just make up an example. Let's say I have a class Foo as shown below. I want the Id and Name properties in the serialization output, but I'm definitely not interested in the AlternateName and Color. I've marked those with [JsonIgnore]. I want the description to appear, but sometimes this can get really long, so I've used a custom JsonConverter to limit its length. I also want to use a shorter property name for the description, so I've marked it with [JsonProperty("Desc")].

class Foo
{
    public int Id { get; set; }
    public string Name { get; set; }
    [JsonIgnore]
    public string AlternateName { get; set; }
    [JsonProperty("Desc")]
    [JsonConverter(typeof(StringTruncatingConverter))]
    public string Description { get; set; }
    [JsonIgnore]
    public string Color { get; set; }
}

When I serialize an instance of the above...

Foo foo = new Foo
{
    Id = 1,
    Name = "Thing 1",
    AlternateName = "The First Thing",
    Description = "This is some lengthy text describing Thing 1 which you'll no doubt find very interesting and useful.",
    Color = "Yellow"
};

string json = JsonConvert.SerializeObject(foo, Formatting.Indented);

...I get this output:

{
  "Id": 1,
  "Name": "Thing 1",
  "Desc": "This is some lengthy text describing Thing 1 "
}

Now, let's say that I sometimes want to get the full JSON output, ignoring my customizations. I can use a custom ContractResolver to programmatically "unapply" the attributes from the class. Here's the code for the resolver:

class IgnoreJsonAttributesResolver : DefaultContractResolver
{
    protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
    {
        IList<JsonProperty> props = base.CreateProperties(type, memberSerialization);
        foreach (var prop in props)
        {
            prop.Ignored = false;   // Ignore [JsonIgnore]
            prop.Converter = null;  // Ignore [JsonConverter]
            prop.PropertyName = prop.UnderlyingName;  // restore original property name
        }
        return props;
    }
}

To use the resolver, I add it to the JsonSerializerSettings and pass the settings to the serializer like this:

JsonSerializerSettings settings = new JsonSerializerSettings();
settings.ContractResolver = new IgnoreJsonAttributesResolver();
settings.Formatting = Formatting.Indented;

string json = JsonConvert.SerializeObject(foo, settings);

The output now includes the ignored properties, and the description is no longer truncated:

{
  "Id": 1,
  "Name": "Thing 1",
  "AlternateName": "The First Thing",
  "Description": "This is some lengthy text describing Thing 1 which you'll no doubt find very interesting and useful.",
  "Color": "Yellow"
}

Full demo here: https://dotnetfiddle.net/WZpeWt

System.Text.Json add JsonIgnore attribute at runtime

After looking in Custom Converters, already found my answer.

here's my converter

public class DataConverter : JsonConverter<Data>
{
    public override Data Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        throw new NotImplementedException();
    }

    public override void Write(Utf8JsonWriter writer, Data value, JsonSerializerOptions options)
    {
        var properties = value.GetType().GetProperties();

        writer.WriteStartObject();

        foreach (var prop in properties)
        {
            if (prop.HasAttribute<ShouldSerializeAttribute>())
            {
                var acceptedTypes = prop.GetAttributeValue<ShouldSerializeAttribute, string[]>(x => x.AcceptedTypes);
                if (acceptedTypes != null && acceptedTypes.Contains(value.Type))
                {
                    var propValue = prop.GetValue(value);
                    writer.WritePropertyName(prop.Name);
                    JsonSerializer.Serialize(writer, propValue, prop.PropertyType, options);
                }
            }
        }

        writer.WriteEndObject();
    }
}

Dynamically ignore the properties on class using json.net

Json.NET has the ability to conditionally serialize properties by placing a ShouldSerialize method on a class.

the following link will give details
http://www.newtonsoft.com/json/help/html/conditionalproperties.htm

Newtonsoft ignore attributes?

I ended up making all properties I needed to only add attributes to virtual, and overriding them alone in another class, with the relevant newtonsoft attributes.

This allows me to have different serialisation behavior when de-serialising from CouchDB and serialising for a GET, without too much dupe. It is fine, and a bonus, that the two are coupled; any changes in the base i would want anyway.

It would still be nice to know if my original question is possible?

---

Related Topics