com.fasterxml.jackson.databind.deser.impl

Class TypeWrappedDeserializer

java.lang.Object

com.fasterxml.jackson.databind.JsonDeserializer<Object>

com.fasterxml.jackson.databind.deser.impl.TypeWrappedDeserializer

All Implemented Interfaces:

NullValueProvider, Serializable

public final class TypeWrappedDeserializer
extends JsonDeserializer<Object>
implements Serializable

Simple deserializer that will call configured type deserializer, passing in configured data deserializer, and exposing it all as a simple deserializer. This is necessary when there is no "parent" deserializer which could handle details of calling a TypeDeserializer, most commonly used with root values.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class com.fasterxml.jackson.databind.JsonDeserializer

JsonDeserializer.None

Field Summary

Fields

Modifier and Type	Field and Description
protected JsonDeserializer<Object>	_deserializer
protected TypeDeserializer	_typeDeserializer

Constructor Summary

Constructors

Constructor and Description
TypeWrappedDeserializer(TypeDeserializer typeDeser, JsonDeserializer<?> deser)

Method Summary

Modifier and Type	Method and Description
Object	deserialize(JsonParser p, DeserializationContext ctxt) Method that can be called to ask implementation to deserialize JSON content into the value type this serializer handles.
Object	deserialize(JsonParser p, DeserializationContext ctxt, Object intoValue) Alternate deserialization method (compared to the most commonly used, JsonDeserializer.deserialize(JsonParser, DeserializationContext)), which takes in initialized value instance, to be configured and/or populated by deserializer.
Object	deserializeWithType(JsonParser p, DeserializationContext ctxt, TypeDeserializer typeDeserializer) Deserialization called when type being deserialized is defined to contain additional type identifier, to allow for correctly instantiating correct subtype.
JsonDeserializer<?>	getDelegatee() Accessor that can be used to determine if this deserializer uses another deserializer for actual deserialization, by delegating calls.
Object	getEmptyValue(DeserializationContext ctxt) Method called to determine value to be used for "empty" values (most commonly when deserializing from empty JSON Strings).
Collection<Object>	getKnownPropertyNames() Method that will either return null to indicate that type being deserializers has no concept of properties; or a collection of identifiers for which toString will give external property name.
Object	getNullValue(DeserializationContext ctxt) Method that can be called to determine value to be used for representing null values (values deserialized when JSON token is JsonToken.VALUE_NULL).
Class<?>	handledType() Method for accessing concrete physical type of values this deserializer produces.
LogicalType	logicalType() Method for accessing logical type of values this deserializer produces.
Boolean	supportsUpdate(DeserializationConfig config) Introspection method that may be called to see whether deserializer supports update of an existing value (aka "merging") or not.

Methods inherited from class com.fasterxml.jackson.databind.JsonDeserializer

deserializeWithType, findBackReference, getAbsentValue, getEmptyAccessPattern, getEmptyValue, getNullAccessPattern, getNullValue, getObjectIdReader, isCachable, replaceDelegatee, unwrappingDeserializer

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

_typeDeserializer

protected final TypeDeserializer _typeDeserializer

_deserializer

protected final JsonDeserializer<Object> _deserializer

Constructor Detail

TypeWrappedDeserializer

public TypeWrappedDeserializer(TypeDeserializer typeDeser,
                               JsonDeserializer<?> deser)

Method Detail

logicalType

public LogicalType logicalType()

Description copied from class: JsonDeserializer

Method for accessing logical type of values this deserializer produces. Typically used for further configuring handling of values, for example, to find which coercions are legal.

Overrides:

logicalType in class JsonDeserializer<Object>

Returns:

Logical type of values this deserializer produces, if known; null if not

handledType

public Class<?> handledType()

Description copied from class: JsonDeserializer

Method for accessing concrete physical type of values this deserializer produces. Note that this information is not guaranteed to be exact -- it may be a more generic (super-type) -- but it should not be incorrect (return a non-related type).

Default implementation will return null, which means almost same same as returning Object.class would; that is, that nothing is known about handled type.

Overrides:

handledType in class JsonDeserializer<Object>

Returns:

Physical type of values this deserializer produces, if known; null if not

supportsUpdate

public Boolean supportsUpdate(DeserializationConfig config)

Description copied from class: JsonDeserializer

Introspection method that may be called to see whether deserializer supports update of an existing value (aka "merging") or not. Return value should either be Boolean.FALSE if update is not supported at all (immutable values); Boolean.TRUE if update should usually work (regular POJOs, for example), or null if this is either not known, or may sometimes work.

Information gathered is typically used to either prevent merging update for property (either by skipping, if based on global defaults; or by exception during deserialization construction if explicit attempt made) if Boolean.FALSE returned, or inclusion if Boolean.TRUE is specified. If "unknown" case (null returned) behavior is to exclude property if global defaults used; or to allow if explicit per-type or property merging is defined.

Default implementation returns null to allow explicit per-type or per-property attempts.

Overrides:

supportsUpdate in class JsonDeserializer<Object>

getDelegatee

public JsonDeserializer<?> getDelegatee()

Description copied from class: JsonDeserializer

Accessor that can be used to determine if this deserializer uses another deserializer for actual deserialization, by delegating calls. If so, will return immediate delegate (which itself may delegate to further deserializers); otherwise will return null.

Overrides:

getDelegatee in class JsonDeserializer<Object>

Returns:

Deserializer this deserializer delegates calls to, if null; null otherwise.

getKnownPropertyNames

public Collection<Object> getKnownPropertyNames()

Description copied from class: JsonDeserializer

Method that will either return null to indicate that type being deserializers has no concept of properties; or a collection of identifiers for which toString will give external property name. This is only to be used for error reporting and diagnostics purposes (most commonly, to accompany "unknown property" exception).

Overrides:

getKnownPropertyNames in class JsonDeserializer<Object>

getNullValue

public Object getNullValue(DeserializationContext ctxt)
                    throws JsonMappingException

Description copied from class: JsonDeserializer

Method that can be called to determine value to be used for representing null values (values deserialized when JSON token is JsonToken.VALUE_NULL). Usually this is simply Java null, but for some types (especially primitives) it may be necessary to use non-null values.

This method may be called once, or multiple times, depending on what JsonDeserializer.getNullAccessPattern() returns.

Default implementation simply returns null.

Specified by:

getNullValue in interface NullValueProvider

Overrides:

getNullValue in class JsonDeserializer<Object>

Throws:

JsonMappingException

getEmptyValue

public Object getEmptyValue(DeserializationContext ctxt)
                     throws JsonMappingException

Description copied from class: JsonDeserializer

Method called to determine value to be used for "empty" values (most commonly when deserializing from empty JSON Strings). Usually this is same as JsonDeserializer.getNullValue(com.fasterxml.jackson.databind.DeserializationContext) (which in turn is usually simply Java null), but it can be overridden for specific types. Or, if type should never be converted from empty String, method can also throw an exception.

This method may be called once, or multiple times, depending on what JsonDeserializer.getEmptyAccessPattern() returns.

Default implementation simply calls JsonDeserializer.getNullValue(com.fasterxml.jackson.databind.DeserializationContext) and returns value.

Overrides:

getEmptyValue in class JsonDeserializer<Object>

Throws:

JsonMappingException

deserialize

public Object deserialize(JsonParser p,
                          DeserializationContext ctxt)
                   throws IOException

Description copied from class: JsonDeserializer

Method that can be called to ask implementation to deserialize JSON content into the value type this serializer handles. Returned instance is to be constructed by method itself.

Pre-condition for this method is that the parser points to the first event that is part of value to deserializer (and which is never JSON 'null' literal, more on this below): for simple types it may be the only value; and for structured types the Object start marker or a FIELD_NAME.

The two possible input conditions for structured types result from polymorphism via fields. In the ordinary case, Jackson calls this method when it has encountered an OBJECT_START, and the method implementation must advance to the next token to see the first field name. If the application configures polymorphism via a field, then the object looks like the following.

      {
          "@class": "class name",
          ...
      }
  

Jackson consumes the two tokens (the @class field name and its value) in order to learn the class and select the deserializer. Thus, the stream is pointing to the FIELD_NAME for the first field after the @class. Thus, if you want your method to work correctly both with and without polymorphism, you must begin your method with:

       if (p.currentToken() == JsonToken.START_OBJECT) {
         p.nextToken();
       }
  

This results in the stream pointing to the field name, so that the two conditions align.

Post-condition is that the parser will point to the last event that is part of deserialized value (or in case deserialization fails, event that was not recognized or usable, which may be the same event as the one it pointed to upon call).

Note that this method is never called for JSON null literal, and thus deserializers need (and should) not check for it.

Specified by:

deserialize in class JsonDeserializer<Object>

Parameters:

p - Parsed used for reading JSON content

ctxt - Context that can be used to access information about this deserialization activity.

Returns:

Deserialized value

Throws:

IOException

deserializeWithType

public Object deserializeWithType(JsonParser p,
                                  DeserializationContext ctxt,
                                  TypeDeserializer typeDeserializer)
                           throws IOException

Description copied from class: JsonDeserializer

Deserialization called when type being deserialized is defined to contain additional type identifier, to allow for correctly instantiating correct subtype. This can be due to annotation on type (or its supertype), or due to global settings without annotations.

Default implementation may work for some types, but ideally subclasses should not rely on current default implementation. Implementation is mostly provided to avoid compilation errors with older code.

Overrides:

deserializeWithType in class JsonDeserializer<Object>

typeDeserializer - Deserializer to use for handling type information

Throws:

IOException

deserialize

public Object deserialize(JsonParser p,
                          DeserializationContext ctxt,
                          Object intoValue)
                   throws IOException

Description copied from class: JsonDeserializer

Alternate deserialization method (compared to the most commonly used, JsonDeserializer.deserialize(JsonParser, DeserializationContext)), which takes in initialized value instance, to be configured and/or populated by deserializer. Method is not necessarily used (or supported) by all types (it will not work for immutable types, for obvious reasons): most commonly it is used for Collections and Maps. It may be used both with "updating readers" (for POJOs) and when Collections and Maps use "getter as setter".

Default implementation just throws UnsupportedOperationException, to indicate that types that do not explicitly add support do not necessarily support update-existing-value operation (esp. immutable types)

Overrides:

deserialize in class JsonDeserializer<Object>

Throws:

IOException