JsonNullableDeserializer.java

package org.openapitools.jackson.nullable;


import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonToken;
import com.fasterxml.jackson.databind.DeserializationConfig;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.deser.ValueInstantiator;
import com.fasterxml.jackson.databind.deser.std.ReferenceTypeDeserializer;
import com.fasterxml.jackson.databind.jsontype.TypeDeserializer;
import com.fasterxml.jackson.databind.type.ReferenceType;

import java.io.IOException;

public class JsonNullableDeserializer extends ReferenceTypeDeserializer<JsonNullable<Object>> {

    private static final long serialVersionUID = 1L;

    private boolean isStringDeserializer = false;
    private final boolean mapBlankStringToNull;

    /*
    /**********************************************************
    /* Life-cycle
    /**********************************************************
     */
    public JsonNullableDeserializer(JavaType fullType, ValueInstantiator inst,
                                    TypeDeserializer typeDeser, JsonDeserializer<?> deser,
                                    boolean mapBlankStringToNull) {
        super(fullType, inst, typeDeser, deser);
        this.mapBlankStringToNull = mapBlankStringToNull;
        if (fullType instanceof ReferenceType && ((ReferenceType) fullType).getReferencedType() != null) {
            this.isStringDeserializer = ((ReferenceType) fullType).getReferencedType().isTypeOrSubTypeOf(String.class);
        }
    }

    /*
    /**********************************************************
    /* Abstract method implementations
    /**********************************************************
     */

    @Override
    public JsonNullable<Object> deserialize(JsonParser p, DeserializationContext ctxt) throws IOException {
        JsonToken t = p.getCurrentToken();
        if (t == JsonToken.VALUE_STRING && !isStringDeserializer) {
            String str = p.getText().trim();
            if (str.isEmpty()) {
                return mapBlankStringToNull ? JsonNullable.of(null) : JsonNullable.undefined();
            }
        }
        return super.deserialize(p, ctxt);
    }

    @Override
    public JsonNullableDeserializer withResolved(TypeDeserializer typeDeser, JsonDeserializer<?> valueDeser) {
        return new JsonNullableDeserializer(_fullType, _valueInstantiator,
                typeDeser, valueDeser, mapBlankStringToNull);
    }

    @Override
    public Object getAbsentValue(DeserializationContext ctxt) {
        return JsonNullable.undefined();
    }

    @Override
    public JsonNullable<Object> getNullValue(DeserializationContext ctxt) {
        return JsonNullable.of(null);
    }

    @Override
    public Object getEmptyValue(DeserializationContext ctxt) {
        return JsonNullable.undefined();
    }

    @Override
    public JsonNullable<Object> referenceValue(Object contents) {
        return JsonNullable.of(contents);
    }

    @Override
    public Object getReferenced(JsonNullable<Object> reference) {
        return reference.get();
    }

    @Override
    public JsonNullable<Object> updateReference(JsonNullable<Object> reference, Object contents) {
        return JsonNullable.of(contents);
    }

    @Override
    public Boolean supportsUpdate(DeserializationConfig config) {
        // yes; regardless of value deserializer reference itself may be updated
        return Boolean.TRUE;
    }
}