public abstract Class DelegatingDeserializer

Implements com.fasterxml.jackson.databind.deser.ContextualDeserializer.createContextual.

Doc from com.fasterxml.jackson.databind.deser.ContextualDeserializer.createContextual.

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.

Parameters

ctxt:DeserializationContext

Deserialization context to access configuration, additional deserializers that may be needed by this deserializer

property:BeanProperty

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:JsonDeserializer<?>

Deserializer to use for deserializing values of specified property; may be this instance or a new instance.

Annotations

@Override

Implements abstract com.fasterxml.jackson.databind.JsonDeserializer.deserialize.

Doc from com.fasterxml.jackson.databind.JsonDeserializer.deserialize.

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",
          ...
      }
  

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

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).

Handling null values (JsonToken.VALUE_NULL)
: Note that this method is never called for the JSON null literal to avoid every deserializer from having to handle null values. Instead, the JsonDeserializer#getNullValue(DeserializationContext) method is called to produce a null value. To influence null handling, custom deserializers should override JsonDeserializer#getNullValue(DeserializationContext) and usually also JsonDeserializer#getNullAccessPattern().

Parameters

p:JsonParser

Parser used for reading JSON content

ctxt:DeserializationContext

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

Returns:Object

Deserialized value

Annotations

@Override

Overrides com.fasterxml.jackson.databind.JsonDeserializer.deserialize.

Doc from com.fasterxml.jackson.databind.JsonDeserializer.deserialize.

Alternate deserialization method (compared to the most commonly used, 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)

Annotations

@SuppressWarnings:unchecked

@Override

Overrides com.fasterxml.jackson.databind.deser.std.StdDeserializer.deserializeWithType.

Doc from com.fasterxml.jackson.databind.deser.std.StdDeserializer.deserializeWithType.

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.

Parameters

typeDeserializer:TypeDeserializer

Doc from com.fasterxml.jackson.databind.JsonDeserializer.deserializeWithType.

Deserializer to use for handling type information

Annotations

@Override

Overrides com.fasterxml.jackson.databind.JsonDeserializer.findBackReference.

Doc from com.fasterxml.jackson.databind.JsonDeserializer.findBackReference.

Method needed by BeanDeserializerFactory to properly link managed- and back-reference pairs.

Annotations

@Override

Overrides com.fasterxml.jackson.databind.JsonDeserializer.getAbsentValue.

Overrides default com.fasterxml.jackson.databind.deser.NullValueProvider.getAbsentValue.

Doc from com.fasterxml.jackson.databind.JsonDeserializer.getAbsentValue.

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 getNullValue (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 getNullValue and returns value.

Annotations

@Override

Overrides com.fasterxml.jackson.databind.JsonDeserializer.getDelegatee.

Doc from com.fasterxml.jackson.databind.JsonDeserializer.getDelegatee.

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.

Returns:JsonDeserializer<?>

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

Annotations

@Override

Overrides com.fasterxml.jackson.databind.JsonDeserializer.getEmptyAccessPattern.

Doc from com.fasterxml.jackson.databind.JsonDeserializer.getEmptyAccessPattern.

This method may be called in conjunction with calls to getEmptyValue(DeserializationContext), to check whether it needs to be called just once (static values), or each time empty value is needed.

Annotations

@Override

Overrides com.fasterxml.jackson.databind.JsonDeserializer.getEmptyValue.

Doc from com.fasterxml.jackson.databind.JsonDeserializer.getEmptyValue.

Method called to determine value to be used for "empty" values (most commonly when deserializing from empty JSON Strings). Usually this is same as getNullValue (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 getEmptyAccessPattern() returns.

Default implementation simply calls getNullValue and returns value.

Annotations

@Override

Overrides com.fasterxml.jackson.databind.JsonDeserializer.getKnownPropertyNames.

Doc from com.fasterxml.jackson.databind.JsonDeserializer.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. This is only to be used for error reporting and diagnostics purposes (most commonly, to accompany "unknown property" exception).

Annotations

@Override

Overrides com.fasterxml.jackson.databind.JsonDeserializer.getNullAccessPattern.

Implements com.fasterxml.jackson.databind.deser.NullValueProvider.getNullAccessPattern.

Doc from com.fasterxml.jackson.databind.JsonDeserializer.getNullAccessPattern.

This method may be called in conjunction with calls to 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 getNullValue(DeserializationContext) need not be called more than once per deserializer instance. This information may be used as optimization.

Annotations

@Override

Overrides com.fasterxml.jackson.databind.JsonDeserializer.getNullValue.

Implements com.fasterxml.jackson.databind.deser.NullValueProvider.getNullValue.

Doc from com.fasterxml.jackson.databind.JsonDeserializer.getNullValue.

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 getNullAccessPattern() returns.

Default implementation simply returns null.

Annotations

@Override

Overrides com.fasterxml.jackson.databind.JsonDeserializer.getObjectIdReader.

Doc from com.fasterxml.jackson.databind.JsonDeserializer.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.

Default implementation returns null, as support cannot be implemented generically. Some standard deserializers (most notably com.fasterxml.jackson.databind.deser.BeanDeserializer) do implement this feature, and may return reader instance, depending on exact configuration of instance (which is based on type, and referring property).

Returns:ObjectIdReader

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.

Annotations

@Override

Overrides com.fasterxml.jackson.databind.JsonDeserializer.isCachable.

Doc from com.fasterxml.jackson.databind.JsonDeserializer.isCachable.

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 com.fasterxml.jackson.databind.deser.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.

Annotations

@Override

Overrides com.fasterxml.jackson.databind.JsonDeserializer.logicalType.

Doc from com.fasterxml.jackson.databind.JsonDeserializer.logicalType.

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.

Returns:LogicalType

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

Annotations

@Override

Overrides com.fasterxml.jackson.databind.JsonDeserializer.replaceDelegatee.

Doc from com.fasterxml.jackson.databind.JsonDeserializer.replaceDelegatee.

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.

Annotations

@Override

Implements com.fasterxml.jackson.databind.deser.ResolvableDeserializer.resolve.

Doc from com.fasterxml.jackson.databind.deser.ResolvableDeserializer.resolve.

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).

Parameters

ctxt:DeserializationContext

Context to use for accessing configuration, resolving secondary deserializers

Annotations

@Override

Overrides com.fasterxml.jackson.databind.JsonDeserializer.supportsUpdate.

Doc from com.fasterxml.jackson.databind.JsonDeserializer.supportsUpdate.

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.

Annotations

@Override

Overrides com.fasterxml.jackson.databind.JsonDeserializer.unwrappingDeserializer.

Doc from com.fasterxml.jackson.databind.JsonDeserializer.unwrappingDeserializer.

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

Annotations

@SuppressWarnings:unchecked

@Override