com.facebook.presto.jdbc.internal.jackson.databind.deser.ContextualDeserializer Maven / Gradle / Ivy
package com.facebook.presto.jdbc.internal.jackson.databind.deser;
import com.facebook.presto.jdbc.internal.jackson.databind.*;
/**
* Add-on interface that {@link JsonDeserializer}s can implement to get a callback
* that can be used to create contextual (context-dependent) instances of
* deserializer to use for handling properties of supported type.
* This can be useful
* for deserializers that can be configured by annotations, or should otherwise
* have differing behavior depending on what kind of property is being deserialized.
*
* Note that in cases where deserializer needs both contextualization and
* resolution -- that is, implements both this interface and {@link ResolvableDeserializer}
* -- resolution via {@link ResolvableDeserializer} occurs first, and contextual
* resolution (via this interface) later on.
*/
public 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.
*
* @param ctxt Deserialization context to access configuration, additional
* deserializers that may be needed by this deserializer
* @param 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)
*
* @return Deserializer to use for deserializing values of specified property;
* may be this instance or a new instance.
*
* @throws JsonMappingException
*/
public JsonDeserializer createContextual(DeserializationContext ctxt,
BeanProperty property)
throws JsonMappingException;
}