Package com.fasterxml.jackson.databind.deser.std

Class NullifyingDeserializer

java.lang.Object

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

com.fasterxml.jackson.databind.deser.std.StdDeserializer<java.lang.Object>

com.fasterxml.jackson.databind.deser.std.NullifyingDeserializer

All Implemented Interfaces:

NullValueProvider, ValueInstantiator.Gettable, java.io.Serializable

public class NullifyingDeserializer
extends StdDeserializer<java.lang.Object>

Bogus deserializer that will simply skip all content there is to map and returns Java null reference.

Since:

2.2

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	Description
static NullifyingDeserializer	instance

Constructor Summary

Constructors

Constructor	Description
NullifyingDeserializer()

Method Summary

Modifier and Type	Method	Description
java.lang.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.
java.lang.Object	deserializeWithType(JsonParser p, DeserializationContext ctxt, TypeDeserializer typeDeserializer)	Base implementation that does not assume specific type inclusion mechanism.
java.lang.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.deser.std.StdDeserializer

getValueClass, getValueInstantiator, getValueType, getValueType, handledType

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

deserialize, deserializeWithType, findBackReference, getAbsentValue, getDelegatee, getEmptyAccessPattern, getEmptyValue, getEmptyValue, getKnownPropertyNames, getNullAccessPattern, getNullValue, getNullValue, getObjectIdReader, isCachable, logicalType, replaceDelegatee, unwrappingDeserializer

Methods inherited from class java.lang.Object

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

Field Detail

instance

public static final NullifyingDeserializer instance

Constructor Detail

NullifyingDeserializer

public NullifyingDeserializer()

Method Detail

supportsUpdate

public java.lang.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<java.lang.Object>

deserialize

public java.lang.Object deserialize(JsonParser p,
                                    DeserializationContext ctxt)
                             throws java.io.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<java.lang.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:

java.io.IOException

deserializeWithType

public java.lang.Object deserializeWithType(JsonParser p,
                                            DeserializationContext ctxt,
                                            TypeDeserializer typeDeserializer)
                                     throws java.io.IOException

Description copied from class: StdDeserializer

Base implementation that does not assume specific type inclusion mechanism. Sub-classes are expected to override this method if they are to handle type information.

Overrides:

deserializeWithType in class StdDeserializer<java.lang.Object>

typeDeserializer - Deserializer to use for handling type information

Throws:

java.io.IOException