Add PdxInstanceWrapper class to wrap (decorate) existing PdxInstances and more appropriately handle JSON to Object mappings returned by getObject().
This commit is contained in:
John Blum
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/*
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* Copyright 2020 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
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* or implied. See the License for the specific language governing
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* permissions and limitations under the License.
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*/
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package org.springframework.geode.pdx;
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import static org.springframework.geode.util.GeodeAssertions.assertThat;
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import java.io.DataOutput;
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import java.io.IOException;
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import java.util.Collections;
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import java.util.List;
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import java.util.Objects;
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import java.util.Optional;
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import com.fasterxml.jackson.databind.DeserializationFeature;
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import com.fasterxml.jackson.databind.MapperFeature;
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import com.fasterxml.jackson.databind.ObjectMapper;
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import org.apache.geode.internal.Sendable;
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import org.apache.geode.pdx.JSONFormatter;
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import org.apache.geode.pdx.PdxInstance;
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import org.apache.geode.pdx.WritablePdxInstance;
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/**
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* The {@link PdxInstanceWrapper} class is an implementation of the {@link PdxInstance} interface
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* wrapping an existing {@link PdxInstance} object and decorating the functionality.
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*
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* @author John Blum
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* @see java.util.function.Function
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* @see com.fasterxml.jackson.databind.ObjectMapper
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* @see org.apache.geode.pdx.JSONFormatter
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* @see org.apache.geode.pdx.PdxInstance
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* @see org.apache.geode.pdx.WritablePdxInstance
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* @since 1.3.0
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*/
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public class PdxInstanceWrapper implements PdxInstance, Sendable {
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public static final String AT_IDENTIFIER_FIELD_NAME = "@identifier";
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public static final String AT_TYPE_FIELD_NAME = "@type";
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public static final String CLASS_NAME_PROPERTY = "className";
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public static final String ID_FIELD_NAME = "id";
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protected static final String ARRAY_BEGIN = "[";
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protected static final String ARRAY_END = "]";
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protected static final String COMMA = ",";
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protected static final String EMPTY_STRING = "";
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protected static final String FIELD_TYPE_VALUE = "\"%1$s\"(%2$s): \"%3$s\"";
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protected static final String INDENT_STRING = "\t";
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protected static final String NEW_LINE = "\n";
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protected static final String COMMA_NEW_LINE = "," + NEW_LINE;
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protected static final String COMMA_SPACE = COMMA + " ";
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protected static final String OBJECT_BEGIN = "{";
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protected static final String OBJECT_END = "}";
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/**
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* Smart, {@literal null-safe} factory method used to evaluate the given {@link Object} and wrap the {@link Object}
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* in a new instance of {@link PdxInstanceWrapper} if the {@link Object} is an instance of {@link PdxInstance}
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* or return the given {@link Object} as is.
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*
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* @param target {@link Object} to evaluate
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* @return the {@link Object} wrapped in a new instance of {@link PdxInstanceWrapper} if {@link Object}
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* is an instance of {@link PdxInstance}, otherwise returns the given {@link Object}.
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* @see org.apache.geode.pdx.PdxInstance
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* @see java.lang.Object
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* @see #from(PdxInstance)
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*/
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public static Object from(Object target) {
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return target instanceof PdxInstance ? from((PdxInstance) target) : target;
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}
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/**
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* Factory method used to construct a new instance of {@link PdxInstanceWrapper} initialized with the given,
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* required {@link PdxInstance} used to back the wrapper.
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*
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* @param pdxInstance {@link PdxInstance} object used to back this wrapper; must not be {@literal null}.
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* @return a new instance of {@link PdxInstanceWrapper} initialized with the given {@link PdxInstance}.
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* @throws IllegalArgumentException if {@link PdxInstance} is {@literal null}.
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* @see org.apache.geode.pdx.PdxInstance
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* @see #PdxInstanceWrapper(PdxInstance)
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*/
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public static PdxInstanceWrapper from(PdxInstance pdxInstance) {
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return new PdxInstanceWrapper(pdxInstance);
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}
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private final PdxInstance delegate;
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/**
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* Constructs a new instance of {@link PdxInstanceWrapper} initialized with the given, required {@link PdxInstance}
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* object used to back this wrapper.
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*
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* @param pdxInstance {@link PdxInstance} object used to back this wrapper; must not be {@literal null}.
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* @throws IllegalArgumentException if {@link PdxInstance} is {@literal null}.
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* @see org.apache.geode.pdx.PdxInstance
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*/
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public PdxInstanceWrapper(PdxInstance pdxInstance) {
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assertThat(pdxInstance).isNotNull();
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this.delegate = pdxInstance;
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}
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/**
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* Returns a reference to the configured, underlying {@link PdxInstance} backing this wrapper.
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*
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* @return a reference to the configured, underlying {@link PdxInstance} backing this wrapper;
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* never {@literal null}.
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* @see org.apache.geode.pdx.PdxInstance
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*/
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protected PdxInstance getDelegate() {
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return this.delegate;
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}
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/**
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* Returns an {@link Optional} reference to a configured Jackson {@link ObjectMapper} used to
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* deserialize the {@link String JSON} generated from {@link PdxInstance PDX} back into an {@link Object}.
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*
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* This method is meant ot be overridden by {@link Class subclasses}.
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*
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* @return an {@link Optional} {@link ObjectMapper}.
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* @see com.fasterxml.jackson.databind.ObjectMapper
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* @see java.util.Optional
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*/
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protected Optional<ObjectMapper> getObjectMapper() {
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ObjectMapper objectMapper = newObjectMapper()
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.configure(DeserializationFeature.FAIL_ON_IGNORED_PROPERTIES, false)
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.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
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.configure(MapperFeature.ACCEPT_CASE_INSENSITIVE_ENUMS, true)
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.findAndRegisterModules();
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return Optional.of(objectMapper);
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}
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/**
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* Constructs a new instance of Jackson's {@link ObjectMapper}.
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*
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* @return a new instance of Jackson's {@link ObjectMapper}; never {@literal null}.
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* @see com.fasterxml.jackson.databind.ObjectMapper
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*/
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ObjectMapper newObjectMapper() {
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return new ObjectMapper();
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}
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/**
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* @inheritDoc
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*/
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@Override
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public String getClassName() {
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return getDelegate().getClassName();
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}
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/**
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* @inheritDoc
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*/
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@Override
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public boolean isDeserializable() {
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return getDelegate().isDeserializable();
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}
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/**
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* @inheritDoc
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*/
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@Override
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public boolean isEnum() {
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return getDelegate().isEnum();
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}
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/**
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* @inheritDoc
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*/
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@Override
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public boolean isIdentityField(String fieldName) {
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return getDelegate().isIdentityField(fieldName);
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}
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/**
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* @inheritDoc
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*/
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@Override
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public Object getField(String fieldName) {
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return getDelegate().getField(fieldName);
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}
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/**
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* @inheritDoc
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*/
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@Override
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public List<String> getFieldNames() {
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return getDelegate().getFieldNames();
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}
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/**
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* @inheritDoc
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*/
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@Override
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public Object getObject() {
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return getObjectMapper()
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.filter(objectMapper -> JSONFormatter.JSON_CLASSNAME.equals(getClassName()))
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.filter(objectMapper -> hasField(AT_TYPE_FIELD_NAME))
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.<Object>map(objectMapper -> {
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try {
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String typeName = String.valueOf(getField(AT_TYPE_FIELD_NAME));
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Class<?> type = Class.forName(typeName);
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String json = jsonFormatterToJson(getDelegate());
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return objectMapper.readValue(json, type);
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}
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catch (Throwable ignore) {
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// TODO Add log statement
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return null;
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}
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})
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.orElseGet(() -> getDelegate().getObject());
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}
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/**
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* Calls {@link JSONFormatter#toJSON(PdxInstance)} to convert the {@link PdxInstance} into {@link String JSON}.
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*
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* @param pdxInstance {@link PdxInstance} to convert to {@link String JSON}.
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* @return {@link String JSON} generated from the given {@link PdxInstance}.
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* @see org.apache.geode.pdx.JSONFormatter#toJSON(PdxInstance)
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* @see org.apache.geode.pdx.PdxInstance
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*/
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String jsonFormatterToJson(PdxInstance pdxInstance) {
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return JSONFormatter.toJSON(pdxInstance);
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}
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/**
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* @inheritDoc
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*/
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@Override
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public WritablePdxInstance createWriter() {
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return getDelegate().createWriter();
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}
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/**
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* @inheritDoc
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*/
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@Override
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public boolean hasField(String fieldName) {
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return getDelegate().hasField(fieldName);
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}
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/**
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* @inheritDoc
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*/
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@Override
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public void sendTo(DataOutput out) throws IOException {
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PdxInstance delegate = getDelegate();
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if (delegate instanceof Sendable) {
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((Sendable) delegate).sendTo(out);
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}
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}
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/**
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* Returns a {@link String} representation of this {@link PdxInstance}.
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*
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* @return a {@link String} representation of this {@link PdxInstance}.
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* @see java.lang.String
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*/
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@Override
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public String toString() {
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//return getDelegate().toString();
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return toString(this);
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}
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private String toString(PdxInstance pdx) {
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return toString(pdx, "");
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}
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private String toString(PdxInstance pdx, String indent) {
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if (Objects.nonNull(pdx)) {
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StringBuilder buffer = new StringBuilder(OBJECT_BEGIN).append(NEW_LINE);
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String fieldIndent = indent + INDENT_STRING;
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buffer.append(fieldIndent).append(formatFieldValue(CLASS_NAME_PROPERTY, pdx.getClassName()));
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for (String fieldName : nullSafeList(pdx.getFieldNames())) {
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Object fieldValue = pdx.getField(fieldName);
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String valueString = toStringObject(fieldValue, fieldIndent);
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buffer.append(COMMA_NEW_LINE);
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buffer.append(fieldIndent).append(formatFieldValue(fieldName, valueString));
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}
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buffer.append(NEW_LINE).append(indent).append(OBJECT_END);
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return buffer.toString();
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}
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else {
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return null;
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}
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}
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private String toStringArray(Object value, String indent) {
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Object[] array = (Object[]) value;
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StringBuilder buffer = new StringBuilder(ARRAY_BEGIN);
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boolean addComma = false;
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for (Object element : array) {
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buffer.append(addComma ? COMMA_SPACE : EMPTY_STRING);
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buffer.append(toStringObject(element, indent));
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addComma = true;
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}
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buffer.append(ARRAY_END);
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return buffer.toString();
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}
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private String toStringObject(Object value, String indent) {
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return isPdxInstance(value) ? toString((PdxInstance) value, indent)
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: isArray(value) ? toStringArray(value, indent)
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: String.valueOf(value);
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}
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private String formatFieldValue(String fieldName, Object fieldValue) {
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return String.format(FIELD_TYPE_VALUE, fieldName, nullSafeType(fieldValue), fieldValue);
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}
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private boolean isArray(Object value) {
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return Objects.nonNull(value) && value.getClass().isArray();
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}
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private boolean isPdxInstance(Object value) {
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return value instanceof PdxInstance;
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}
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private <T> List<T> nullSafeList(List<T> list) {
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return list != null ? list : Collections.emptyList();
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}
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private Class<?> nullSafeType(Object value) {
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return value != null ? value.getClass() : Object.class;
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}
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}
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