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 using JsonTypeResolver 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
      java.lang.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; for JsonTypeInfo.Id.NONE nothing is included).
      java.lang.String property
      Property names used when type inclusion method (JsonTypeInfo.As.PROPERTY) is used (or possibly when using type metadata of type JsonTypeInfo.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; for JsonTypeInfo.Id.NONE nothing is included). Default

        Note 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

        java.lang.String property
        Property names used when type inclusion method (JsonTypeInfo.As.PROPERTY) is used (or possibly when using type metadata of type JsonTypeInfo.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

        java.lang.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