Annotation Type JsonTypeInfo
-
@Target({TYPE,FIELD,METHOD,PARAMETER}) @Retention(RUNTIME) public @interface JsonTypeInfo
Annotation used for configuring details of if and how type information is used with JSON serialization and deserialization, to preserve information about actual class of Object instances. This is necessarily for polymorphic types, and may also be needed to link abstract declared types and matching concrete implementation.Some examples of typical annotations:
// Include Java class name ("com.myempl.ImplClass") as JSON property "class" @JsonTypeInfo(use=Id.CLASS, include=As.PROPERTY, property="class") // Include logical type name (defined in impl classes) as wrapper; 2 annotations @JsonTypeInfo(use=Id.NAME, include=As.WRAPPER_OBJECT) @JsonSubTypes({com.myemp.Impl1.class, com.myempl.Impl2.class})
Alternatively you can also define fully customized type handling by usingJsonTypeResolver
annotation.NOTE: originally this annotation was only available to use with types (classes), but starting with 1.7, it is also allowed for properties (fields, methods, constructor parameters).
When used for properties (fields, methods), this annotation applies to values: so when applied to structure types (like
Collection
,Map
, arrays), will apply to contained values, not the container; for non-structured types there is no difference. This is identical to how JAXB handles type information annotations; and is chosen since it is the dominant use case. There is no per-property way to force type information to be included for type of container (structured type); for container types one has to use annotation for type declaration.- Since:
- 1.5 (but available to fields, methods and constructor parameters since 1.7)
- Author:
- tatu
- See Also:
JsonTypeResolver
-
-
Required Element Summary
Required Elements Modifier and Type Required Element Description JsonTypeInfo.Id
use
What kind of type metadata is to be used for serializing and deserializing type information for instances of annotated type (and its subtypes unless overridden)
-
Optional Element Summary
Optional Elements Modifier and Type Optional Element Description Class<?>
defaultImpl
Optional property that can be used to specify default implementation class to use if type identifier is either not present, or can not be mapped to a registered type (which can occur for ids, but not when specifying explicit class to use).JsonTypeInfo.As
include
What mechanism is used for including type metadata (if any; forJsonTypeInfo.Id.NONE
nothing is included).String
property
Property names used when type inclusion method (JsonTypeInfo.As.PROPERTY
) is used (or possibly when using type metadata of typeJsonTypeInfo.Id.CUSTOM
).
-
-
-
Element Detail
-
use
JsonTypeInfo.Id use
What kind of type metadata is to be used for serializing and deserializing type information for instances of annotated type (and its subtypes unless overridden)
-
-
-
include
JsonTypeInfo.As include
What mechanism is used for including type metadata (if any; forJsonTypeInfo.Id.NONE
nothing is included). DefaultNote that for type metadata type of
JsonTypeInfo.Id.CUSTOM
, this setting may or may not have any effect.- Default:
- org.codehaus.jackson.annotate.JsonTypeInfo.As.PROPERTY
-
-
-
property
String property
Property names used when type inclusion method (JsonTypeInfo.As.PROPERTY
) is used (or possibly when using type metadata of typeJsonTypeInfo.Id.CUSTOM
).Default property name used if this property is not explicitly defined (or is set to empty String) is based on type metadata type (
use()
) used.- Default:
- ""
-
-
-
defaultImpl
Class<?> defaultImpl
Optional property that can be used to specify default implementation class to use if type identifier is either not present, or can not be mapped to a registered type (which can occur for ids, but not when specifying explicit class to use).Note that while this property allows specification of the default implementation to use, it does not help with structural issues that may arise if type information is missing. This means that most often this is used with type-name -based resolution, to cover cases where new sub-types are added, but base type is not changed to reference new sub-types.
- Since:
- 1.9
- Default:
- org.codehaus.jackson.annotate.JsonTypeInfo.None.class
-
-