DelegatingDeserializer (jackson-databind 2.16.1)

java.lang.Object
- com.fasterxml.jackson.databind.JsonDeserializer<T>
- - com.fasterxml.jackson.databind.deser.std.StdDeserializer<Object>
  - - com.fasterxml.jackson.databind.deser.std.DelegatingDeserializer

All Implemented Interfaces:

ContextualDeserializer, NullValueProvider, ResolvableDeserializer, ValueInstantiator.Gettable, Serializable
```
public abstract class DelegatingDeserializer
extends StdDeserializer<Object>
implements ContextualDeserializer, ResolvableDeserializer
```
Base class that simplifies implementations of JsonDeserializers that mostly delegate functionality to another deserializer implementation (possibly forming a chaining of deserializers delegating functionality in some cases)

Since:

2.1

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<?> _delegatee
- Fields inherited from class com.fasterxml.jackson.databind.deser.std.StdDeserializer
  _valueClass, _valueType, F_MASK_ACCEPT_ARRAYS, F_MASK_INT_COERCIONS

Fields
Modifier and Type	Field and Description
`protected JsonDeserializer<?>`	`_delegatee`

Constructor Summary

Constructors
Constructor and Description

DelegatingDeserializer(JsonDeserializer<?> d)

Constructors
Constructor and Description
`DelegatingDeserializer(JsonDeserializer<?> d)`

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`JsonDeserializer<?>`	`createContextual(DeserializationContext ctxt, BeanProperty property)` Method called to see if a different (or differently configured) deserializer is needed to deserialize values of specified property.
`Object`	`deserialize(com.fasterxml.jackson.core.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(com.fasterxml.jackson.core.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(com.fasterxml.jackson.core.JsonParser p, DeserializationContext ctxt, TypeDeserializer typeDeserializer)` Base implementation that does not assume specific type inclusion mechanism.
`SettableBeanProperty`	`findBackReference(String logicalName)` Method needed by `BeanDeserializerFactory` to properly link managed- and back-reference pairs.
`Object`	`getAbsentValue(DeserializationContext ctxt)` Method called to determine placeholder value to be used for cases where no value was obtained from input but we must pass a value nonetheless: the common case is that of Creator methods requiring passing a value for every parameter.
`JsonDeserializer<?>`	`getDelegatee()` Accessor that can be used to determine if this deserializer uses another deserializer for actual deserialization, by delegating calls.
`AccessPattern`	`getEmptyAccessPattern()` This method may be called in conjunction with calls to `JsonDeserializer.getEmptyValue(DeserializationContext)`, to check whether it needs to be called just once (static values), or each time empty value is needed.
`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.
`AccessPattern`	`getNullAccessPattern()` This method may be called in conjunction with calls to `JsonDeserializer.getNullValue(DeserializationContext)`, to check whether it needs to be called just once (static values), or each time empty value is needed.
`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`).
`ObjectIdReader`	`getObjectIdReader()` Accessor that can be used to check whether this deserializer is expecting to possibly get an Object Identifier value instead of full value serialization, and if so, should be able to resolve it to actual Object instance to return as deserialized value.
`boolean`	`isCachable()` Method called to see if deserializer instance is cachable and usable for other properties of same type (type for which instance was created).
`LogicalType`	`logicalType()` Method for accessing logical type of values this deserializer produces.
`protected abstract JsonDeserializer<?>`	`newDelegatingInstance(JsonDeserializer<?> newDelegatee)`
`JsonDeserializer<?>`	`replaceDelegatee(JsonDeserializer<?> delegatee)` Method that can be called to try to replace deserializer this deserializer delegates calls to.
`void`	`resolve(DeserializationContext ctxt)` Method called after deserializer instance has been constructed (and registered as necessary by provider objects), but before it has returned it to the caller.
`Boolean`	`supportsUpdate(DeserializationConfig config)` Introspection method that may be called to see whether deserializer supports update of an existing value (aka "merging") or not.
`JsonDeserializer<Object>`	`unwrappingDeserializer(NameTransformer unwrapper)` Method that will return deserializer instance that is able to handle "unwrapped" value instances If no unwrapped instance can be constructed, will simply return this object as-is.

Methods inherited from class com.fasterxml.jackson.databind.deser.std.StdDeserializer
_byteOverflow, _checkBooleanToStringCoercion, _checkCoercionFail, _checkDoubleSpecialValue, _checkFloatSpecialValue, _checkFloatToIntCoercion, _checkFloatToStringCoercion, _checkFromStringCoercion, _checkFromStringCoercion, _checkIntToFloatCoercion, _checkIntToStringCoercion, _checkTextualNull, _checkToStringCoercion, _coerceBooleanFromInt, _coercedTypeDesc, _coercedTypeDesc, _coerceEmptyString, _coerceIntegral, _coerceNullToken, _coerceTextualNull, _deserializeFromArray, _deserializeFromEmpty, _deserializeFromEmptyString, _deserializeFromString, _deserializeWrappedValue, _failDoubleToIntCoercion, _findCoercionFromBlankString, _findCoercionFromEmptyArray, _findCoercionFromEmptyString, _findNullProvider, _hasTextualNull, _intOverflow, _isBlank, _isEmptyOrTextualNull, _isFalse, _isIntNumber, _isNaN, _isNegInf, _isPosInf, _isTrue, _neitherNull, _nonNullNumber, _parseBoolean, _parseBooleanFromInt, _parseBooleanPrimitive, _parseBooleanPrimitive, _parseBytePrimitive, _parseDate, _parseDate, _parseDateFromArray, _parseDouble, _parseDouble, _parseDoublePrimitive, _parseDoublePrimitive, _parseDoublePrimitive, _parseFloatPrimitive, _parseFloatPrimitive, _parseFloatPrimitive, _parseInteger, _parseInteger, _parseIntPrimitive, _parseIntPrimitive, _parseLong, _parseLong, _parseLongPrimitive, _parseLongPrimitive, _parseShortPrimitive, _parseString, _parseString, _reportFailedNullCoerce, _shortOverflow, _verifyEndArrayForSingle, _verifyNullForPrimitive, _verifyNullForPrimitiveCoercion, _verifyNullForScalarCoercion, _verifyNumberForScalarCoercion, _verifyStringForScalarCoercion, findContentNullProvider, findContentNullStyle, findConvertingContentDeserializer, findDeserializer, findFormatFeature, findFormatOverrides, findValueNullProvider, getValueClass, getValueInstantiator, getValueType, getValueType, handledType, handleMissingEndArrayForSingle, handleNestedArrayForSingle, handleUnknownProperty, isDefaultDeserializer, isDefaultKeyDeserializer

Methods inherited from class com.fasterxml.jackson.databind.JsonDeserializer
deserializeWithType, getEmptyValue, getNullValue

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - _delegatee
```
protected final JsonDeserializer<?> _delegatee
```
- Constructor Detail
  - DelegatingDeserializer
```
public DelegatingDeserializer(JsonDeserializer<?> d)
```
- Method Detail
  - newDelegatingInstance
```
protected abstract JsonDeserializer<?> newDelegatingInstance(JsonDeserializer<?> newDelegatee)
```
  - resolve
```
public void resolve(DeserializationContext ctxt)
             throws JsonMappingException
```
    Description copied from interface: ResolvableDeserializer
    
    Method called after deserializer instance has been constructed (and registered as necessary by provider objects), but before it has returned it to the caller. Called object can then resolve its dependencies to other types, including self-references (direct or indirect).
    
    Specified by:
    
    resolve in interface ResolvableDeserializer
    
    Parameters:
    
    ctxt - Context to use for accessing configuration, resolving secondary deserializers
    
    Throws:
    
    JsonMappingException
  - createContextual
```
public JsonDeserializer<?> createContextual(DeserializationContext ctxt,
                                            BeanProperty property)
                                     throws JsonMappingException
```
    Description copied from interface: ContextualDeserializer
    
    Method called to see if a different (or differently configured) deserializer is needed to deserialize values of specified property. Note that instance that this method is called on is typically shared one and as a result method should NOT modify this instance but rather construct and return a new instance. This instance should only be returned as-is, in case it is already suitable for use.
    
    Specified by:
    
    createContextual in interface ContextualDeserializer
    
    Parameters:
    
    ctxt - Deserialization context to access configuration, additional deserializers that may be needed by this deserializer
    
    property - Method, field or constructor parameter that represents the property (and is used to assign deserialized value). Should be available; but there may be cases where caller cannot provide it and null is passed instead (in which case impls usually pass 'this' deserializer as is)
    
    Returns:
    
    Deserializer to use for deserializing values of specified property; may be this instance or a new instance.
    
    Throws:
    
    JsonMappingException
  - unwrappingDeserializer
```
public JsonDeserializer<Object> unwrappingDeserializer(NameTransformer unwrapper)
```
    Description copied from class: JsonDeserializer
    
    Method that will return deserializer instance that is able to handle "unwrapped" value instances If no unwrapped instance can be constructed, will simply return this object as-is.
    Default implementation just returns 'this' indicating that no unwrapped variant exists
    
    Overrides:
    
    unwrappingDeserializer in class JsonDeserializer<Object>
  - replaceDelegatee
```
public JsonDeserializer<?> replaceDelegatee(JsonDeserializer<?> delegatee)
```
    Description copied from class: JsonDeserializer
    
    Method that can be called to try to replace deserializer this deserializer delegates calls to. If not supported (either this deserializer does not delegate anything; or it does not want any changes), should either throw UnsupportedOperationException (if operation does not make sense or is not allowed); or return this deserializer as is.
    
    Overrides:
    
    replaceDelegatee in class JsonDeserializer<Object>
  - deserialize
```
public Object deserialize(com.fasterxml.jackson.core.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
  - deserialize
```
public Object deserialize(com.fasterxml.jackson.core.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
  - deserializeWithType
```
public Object deserializeWithType(com.fasterxml.jackson.core.JsonParser p,
                                  DeserializationContext ctxt,
                                  TypeDeserializer typeDeserializer)
                           throws 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<Object>
    
    typeDeserializer - Deserializer to use for handling type information
    
    Throws:
    
    IOException
  - isCachable
```
public boolean isCachable()
```
    Description copied from class: JsonDeserializer
    
    Method called to see if deserializer instance is cachable and usable for other properties of same type (type for which instance was created).
    Note that cached instances are still resolved on per-property basis, if instance implements ResolvableDeserializer: cached instance is just as the base. This means that in most cases it is safe to cache instances; however, it only makes sense to cache instances if instantiation is expensive, or if instances are heavy-weight.
    Default implementation returns false, to indicate that no caching is done.
    
    Overrides:
    
    isCachable in class JsonDeserializer<Object>
  - 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 deserializer 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.
  - findBackReference
```
public SettableBeanProperty findBackReference(String logicalName)
```
    Description copied from class: JsonDeserializer
    
    Method needed by BeanDeserializerFactory to properly link managed- and back-reference pairs.
    
    Overrides:
    
    findBackReference 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
  - getNullAccessPattern
```
public AccessPattern getNullAccessPattern()
```
    Description copied from class: JsonDeserializer
    
    This method may be called in conjunction with calls to JsonDeserializer.getNullValue(DeserializationContext), to check whether it needs to be called just once (static values), or each time empty value is needed.
    Default implementation indicates that the "null value" to use for input null does not vary across uses so that JsonDeserializer.getNullValue(DeserializationContext) need not be called more than once per deserializer instance. This information may be used as optimization.
    
    Specified by:
    
    getNullAccessPattern in interface NullValueProvider
    
    Overrides:
    
    getNullAccessPattern in class JsonDeserializer<Object>
  - getAbsentValue
```
public Object getAbsentValue(DeserializationContext ctxt)
                      throws JsonMappingException
```
    Description copied from class: JsonDeserializer
    
    Method called to determine placeholder value to be used for cases where no value was obtained from input but we must pass a value nonetheless: the common case is that of Creator methods requiring passing a value for every parameter. 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: most notable scalar types must use "default" values.
    This method needs to be called every time a determination is made.
    Default implementation simply calls JsonDeserializer.getNullValue(com.fasterxml.jackson.databind.DeserializationContext) and returns value.
    
    Specified by:
    
    getAbsentValue in interface NullValueProvider
    
    Overrides:
    
    getAbsentValue 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
  - getEmptyAccessPattern
```
public AccessPattern getEmptyAccessPattern()
```
    Description copied from class: JsonDeserializer
    
    This method may be called in conjunction with calls to JsonDeserializer.getEmptyValue(DeserializationContext), to check whether it needs to be called just once (static values), or each time empty value is needed.
    
    Overrides:
    
    getEmptyAccessPattern in class JsonDeserializer<Object>
  - 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
  - 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>
  - getObjectIdReader
```
public ObjectIdReader getObjectIdReader()
```
    Description copied from class: JsonDeserializer
    
    Accessor that can be used to check whether this deserializer is expecting to possibly get an Object Identifier value instead of full value serialization, and if so, should be able to resolve it to actual Object instance to return as deserialized value.
    Default implementation returns null, as support cannot be implemented generically. Some standard deserializers (most notably BeanDeserializer) do implement this feature, and may return reader instance, depending on exact configuration of instance (which is based on type, and referring property).
    
    Overrides:
    
    getObjectIdReader in class JsonDeserializer<Object>
    
    Returns:
    
    ObjectIdReader used for resolving possible Object Identifier value, instead of full value serialization, if deserializer can do that; null if no Object Id is expected.

Class DelegatingDeserializer

Nested Class Summary

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

Field Summary

Fields inherited from class com.fasterxml.jackson.databind.deser.std.StdDeserializer

Constructor Summary

Method Summary

Methods inherited from class com.fasterxml.jackson.databind.deser.std.StdDeserializer

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

Methods inherited from class java.lang.Object

Field Detail

_delegatee

Constructor Detail

DelegatingDeserializer

Method Detail

newDelegatingInstance

resolve

createContextual

unwrappingDeserializer

replaceDelegatee

deserialize

deserialize

deserializeWithType

isCachable

supportsUpdate

getDelegatee

findBackReference

getNullValue

getNullAccessPattern

getAbsentValue

getEmptyValue

getEmptyAccessPattern

logicalType

getKnownPropertyNames

getObjectIdReader