Attributes can be used to control how Json.NET serializes and deserializes .NET objects.

• JsonObjectAttribute - Placed on classes to control how it should be serialized as a JSON object.
• JsonArrayAttribute - Placed on collections to control how it should be serialized as a JSON array.
• JsonPropertyAttribute - Placed on fields and properties to control how it should be serialized as a property in a JSON object.
• JsonConverterAttribute - Placed on either classes or fields and properties to specify which JsonConverter should be used during serialization.

As well as using the built-in Json.NET attributes, Json.NET also looks for the DataContract and DataMember attributes when determining how JSON is to be serialized and deserialized. If both are present the Json.NET serialization attributes take precedence.

[JsonObject(MemberSerialization.OptIn)]

public class Person

{

  // "John Smith"

  [JsonProperty]

  public string Name { get; set; }

  // "2000-12-15T22:11:03"

  [JsonProperty]

  [JsonConverter(typeof(IsoDateTimeConverter))]

  public DateTime BirthDate { get; set; }

  // new Date(976918263055)

  [JsonProperty]

  [JsonConverter(typeof(JavaScriptDateTimeConverter))]

  public DateTime LastModified { get; set; }

  // not serialized

  public string Department { get; set; }

}

JsonObjectAttribute

The MemberSerialization flag on this attribute specifies whether member serialization is opt-in (a member must have the JsonProperty or DataMember attribute to be serialized) or opt-out (everything is serialized by default but can be ignored with the JsonIgnoreAttribute, Json.NET's default behavor).

Json.NET serializes .NET classes that implement IEnumerable as an JSON array populated with the IEnumerable values. Placing the JsonPropertyAttribute overrides this behavor and forces the serializer to serialize the class's fields and properties.

JsonPropertyAttribute

JsonPropertyAttribute has a number of uses:

• By default the JSON property will have the same name as the .NET property. This attribute allows the name to be customized.
• Indicates that a property should be serialized when member serialization is set to opt-in.
• Includes non-public properties in serialization and deserialization.

JsonIgnoreAttribute

Excludes a field or property from serialization.

JsonConverterAttribute

The JsonConverterAttribute specifies which JsonSerializer is used to convert an object.

The attribute can be placed on a class or a member. When placed on a class the JsonConverter specified by the attribute will be the default way of serializing that class. When the attribute is on a field or property then the specified JsonConverter will always be used to serialize that value.

The priority of which JsonConverter is used is member attribute then class attribute and finally any converters passed to the JsonSerializer.

public class MemberConverterClass

{

  public DateTime DefaultConverter { get; set; }

  [JsonConverter(typeof(IsoDateTimeConverter))]

  public DateTime MemberConverter { get; set; }

}

This example shows the JsonConverterAttribute being applied to a property.

DateTime date = Convert.ToDateTime("1970-01-01T00:00:00Z").ToUniversalTime();

MemberConverterClass c = new MemberConverterClass

  {

    DefaultConverter = date,

    MemberConverter = date

  };

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

Console.WriteLine(json);

//{

//  "DefaultConverter": "\/Date(0)\/",

//  "MemberConverter": "1970-01-01T00:00:00Z"

//}