JsonSerializer has a number of properties on it to customize how it serializes JSON. These can also be used with the methods on JsonConvert via the JsonSerializerSettings overloads.
DateFormatHandling
DateFormatHandling controls how dates are serialized.
| Member | Description |
|---|---|
| IsoDateFormat |
By default Json.NET writes dates in the ISO 8601 format, e.g. "2012-03-21T05:40Z".
|
| MicrosoftDateFormat |
Dates are written in the Microsoft JSON format, e.g. "\/Date(1198908717056)\/".
|
MissingMemberHandling
MissingMemberHandling controls how missing members, e.g. JSON contains a property that isn't a member on the object, are handled during deserialization.
| Member | Description |
|---|---|
| Ignore |
By default Json.NET ignores JSON if there is no field
or property for its value to be set to during deserialization.
|
| Error |
Json.NET errors when there is a missing member during
deserialization.
|
ReferenceLoopHandling
ReferenceLoopHandling controls how circular referencing objects, e.g. a Person object referencing itself via a Manager property, are serialized.
| Member | Description |
|---|---|
| Error |
By default Json.NET will error if a reference loop is
encountered (otherwise the serializer will get into an infinite loop).
|
| Ignore |
Json.NET will ignore objects in reference loops and
not serialize them. The first time an object is encountered it will be
serialized as usual but if the object is encountered as a child object of itself
the serializer will skip serializing it.
|
| Serialize |
This option forces Json.NET to serialize objects in
reference loops. This is useful if objects are nested but not indefinitely.
|
ReferenceLoopHandling can also be customized on individual properties with JsonPropertyAttribute.
NullValueHandling
NullValueHandling controls how null values on .NET objects are handled during serialization and how null values in JSON are handled during deserialization.
| Member | Description |
|---|---|
| Include |
By default Json.NET writes null values to JSON when
serializing and sets null values to fields/properties when deserializing.
|
| Ignore |
Json.NET will skip writing JSON properties if the .NET
value is null when serializing and will skip setting fields/properties if the
JSON property is null when deserializing.
|
NullValueHandling can also be customized on individual properties with JsonPropertyAttribute.
DefaultValueHandling
DefaultValueHandling controls how Json.NET uses default values set using the .NET DefaultValueAttribute when serializing and deserializing.
| Member | Description |
|---|---|
| Include |
By default Json.NET will write a field/property value
to JSON when serializing if the value is the same as the field/property's
default value. The Json.NET deserializer will continue setting a field/property
if the JSON value is the same as the default value.
|
| Ignore |
Json.NET will skip writing a field/property value to
JSON if the value is the same as the field/property's default value. The
Json.NET deserializer will skip setting a .NET object's field/property if the
JSON value is the same as the default value.
|
DefaultValueHandling can also be customized on individual properties with JsonPropertyAttribute.
ObjectCreationHandling
ObjectCreationHandling controls how objects are created and deserialized to during deserialization.
| Member | Description |
|---|---|
| Auto |
By default Json.NET will attempt to set JSON values onto
existing objects and add JSON values to existing collections during
deserialization.
|
| Reuse |
Same behaviour as auto.
|
| Replace |
Json.NET will always recreate objects and collections
before setting values to them during deserialization.
|
ObjectCreationHandling can also be customized on individual properties with JsonPropertyAttribute.
TypeNameHandling
TypeNameHandling controls whether Json.NET includes .NET type names during serialization with a $type property and reads .NET type names from that property to determine what type to create during deserialization.
| Member | Description |
|---|---|
| None |
By default Json.NET does not read or write type names
during deserialization.
|
| Objects |
Json.NET will write and use type names for objects
but not collections.
|
| Arrays |
Json.NET will write and use type names for collections
but not objects.
|
| Auto |
Json.NET will check whether an object/collection matches
its declared property and writes the type name if they do not match, e.g. a
property with a type of Mammal has a derived instance of Dog assigned. Auto will
ensure that type information isn't lost when serializing/deserializing
automatically without having to write type names for every object.
|
| All |
Json.NET will write and use type names for objects and
collections.
|
TypeNameHandling can also be customized on individual properties with JsonPropertyAttribute.
TypeNameAssemblyFormat
TypeNameAssemblyFormat controls how type names are written during serialization.
| Member | Description |
|---|---|
| Simple |
By default Json.NET writes the partial assembly name
with the type, e.g. System.Data.DataSet, System.Data. Note that Silverlight and
Windows Phone are not able to use this format.
|
| Full |
Json.NET will write the full assembly name, including
version number, culture and public key token.
|
Read more about the valid values at FormatterAssemblyStyle.
Binder
The serialization binder is used to resolve type names to a .NET type.
Read more about the serialization binder here: SerializationBinder
ConstructorHandling
ConstructorHandling controls how constructors are used when initializing objects during deserialization.
| Member | Description |
|---|---|
| Default |
By default Json.NET will first look for a constructor
marked with the JsonConstructorAttribute, then look for a public default
constructor (a constructor that doesn't take any arguments), then check if
the class has a single public constructor with arguments and finally check
for a non-public default constructor. If the class has multiple public
constructors with arguments an error will be thrown. This can be fixed by
marking one of the constructors with the JsonConstructorAttribute.
|
| AllowNonPublicDefaultConstructor |
Json.NET will use a classes private default constructor before constructors
with arguments if available.
|
Converters
This is the collection of JsonConverters that will be used during serialization and deserialization.
JsonConverters allows JSON to be manually written during serialization and read during deserialization. This is useful for particularly complex JSON structures or for when you want to change how a type is serialized.
When a JsonConverter has been added to a JsonSerializer it will be checked for every value that is being serialized/deserialized using its CanConvert to see if it should be used. If CanConvert returns true then the JsonConverter will be used to read or write the JSON for that value. Note that while a JsonConverter gives you complete control over that values JSON, many Json.NET serialization features are no longer available like type name and reference handling.
To create your own custom converter inherit from the JsonConverter class. Read more about the built-in JsonConverters below:
- Serializing Dates in JSON
- Converting between JSON and XML
- CustomCreationConverter
- StringEnumConverter
ContractResolver
Internally for every .NET type the JsonSerializer will create a contract of how the type should be serialized and deserialized, based on type metadata and attributes applied to the class. Specifying a custom IContractResolver allows the creation of contracts to be customized.
Read more about Contract Resolvers here: Contract Resolvers
Error
The Error event can catch errors during serialization and either handle the event and continue with serialization or let the error bubble up and be thrown to the application.
Read more about error handling here: Serialization Error Handling