使用Json.NET序列化时忽略特定的数据类型？

Question

I'm saving JSON objects into the database, sometimes it grows very large (I have an object of length 205,797 characters) I want to eliminate the size as possible as I can. these objects have a lot of GUID fields, all I don't need, It may help eliminating the size if there is a way to ignore any GUID type from serializing.

This is my code, I pass an object of any model type in my application:

 public static string GetEntityAsJson(object entity)
 {
     var json = JsonConvert.SerializeObject(entity, Formatting.None, new JsonSerializerSettings
     {
         ReferenceLoopHandling = ReferenceLoopHandling.Ignore
     });
     return json;
}

EDIT

I don't want to use JsonIgnore attribute, as I will have to add it to so many classes each has a lot of GUID properties, I'm looking for something straight forward like: IgnoreDataType = DataTypes.GUID

Answer 1

You can use a custom ContractResolver to ignore all properties of a specific data type in all classes. For example, here is one that ignores all Guids :

class IgnoreGuidsResolver : DefaultContractResolver
{
    protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
    {
        JsonProperty prop = base.CreateProperty(member, memberSerialization);
        if (prop.PropertyType == typeof(Guid))
        {
            prop.Ignored = true;
        }
        return prop;
    }
}

To use the resolver, just add it to your JsonSerializerSettings :

var json = JsonConvert.SerializeObject(entity, Formatting.None, new JsonSerializerSettings
{
    ContractResolver = new IgnoreGuidsResolver(),
    ...
});

Demo fiddle: https://dotnetfiddle.net/lOOUfq

Answer 2

Using [JsonIgnore] in your entity class should solve your problem.

public class Plane
{
  // included in JSON
  public string Model { get; set; }
  public DateTime Year { get; set; }

  // ignored
  [JsonIgnore]
  public DateTime LastModified { get; set; }
}

Answer 3

You can create your own Converter

public class MyJsonConverter : JsonConverter
{
    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {

        JObject jo = new JObject();

        foreach (PropertyInfo prop in value.GetType().GetProperties())
        {
            if (prop.CanRead)
            {
                if (prop.PropertyType == typeof(Guid))
                    continue;


                object propValue = prop.GetValue(value);

                if (propValue != null)
                {
                    jo.Add(prop.Name, JToken.FromObject(propValue));
                }
            }
        }
        jo.WriteTo(writer);
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        throw new NotImplementedException();
    }

    public override bool CanConvert(Type objectType)
    {
        return objectType.IsAssignableFrom(objectType);
    }
}

And use it as

static void Main(string[] args)
    {
        Person testObj = new Person
        {
            Id = Guid.NewGuid(),
            Name = "M.A",
            MyAddress = new Address
            {
                AddressId = 1,
                Country = "Egypt"
            }
        };

        var json = JsonConvert.SerializeObject(testObj, new MyJsonConverter());

        Console.WriteLine(json);
    }

Classes

public class Person
{
    public Guid Id { get; set; }

    public string Name { get; set; }

    public Address MyAddress { get; set; }

}

public class Address
{
    public int AddressId { get; set; }

    public string Country { get; set; }

}

I used this reference to Create the converter Json.NET, how to customize serialization to insert a JSON property