/*
* Copyright 2012-2016 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.data.mongodb.core.query;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import org.bson.Document;
import org.springframework.core.convert.converter.Converter;
import com.mongodb.util.JSON;
/**
* Utility methods for JSON serialization.
*
* @author Oliver Gierke
* @author Christoph Strobl
*/
public abstract class SerializationUtils {
private SerializationUtils() {
}
/**
* Flattens out a given {@link Document}.
*
* <pre>
* <code>
* {
* _id : 1
* nested : { value : "conflux"}
* }
* </code>
* will result in
* <code>
* {
* _id : 1
* nested.value : "conflux"
* }
* </code>
* </pre>
*
* @param source can be {@literal null}.
* @return {@link Collections#emptyMap()} when source is {@literal null}
* @since 1.8
*/
public static Map<String, Object> flattenMap(Document source) {
if (source == null) {
return Collections.emptyMap();
}
Map<String, Object> result = new HashMap<String, Object>();
toFlatMap("", source, result);
return result;
}
private static void toFlatMap(String currentPath, Object source, Map<String, Object> map) {
if (source instanceof Document) {
Document document = (Document) source;
Iterator<Map.Entry<String, Object>> iter = document.entrySet().iterator();
String pathPrefix = currentPath.isEmpty() ? "" : currentPath + ".";
while (iter.hasNext()) {
Map.Entry<String, Object> entry = iter.next();
if (entry.getKey().startsWith("$")) {
if (map.containsKey(currentPath)) {
((Document) map.get(currentPath)).put(entry.getKey(), entry.getValue());
} else {
map.put(currentPath, new Document(entry.getKey(), entry.getValue()));
}
} else {
toFlatMap(pathPrefix + entry.getKey(), entry.getValue(), map);
}
}
} else {
map.put(currentPath, source);
}
}
/**
* Serializes the given object into pseudo-JSON meaning it's trying to create a JSON representation as far as possible
* but falling back to the given object's {@link Object#toString()} method if it's not serializable. Useful for
* printing raw {@link Document}s containing complex values before actually converting them into Mongo native types.
*
* @param value
* @return
*/
public static String serializeToJsonSafely(Object value) {
if (value == null) {
return null;
}
try {
return JSON.serialize(value);
} catch (Exception e) {
if (value instanceof Collection) {
return toString((Collection<?>) value);
} else if (value instanceof Map) {
return toString((Map<?, ?>) value);
} else if (value instanceof Document) {
return toString(((Document) value));
} else {
return String.format("{ $java : %s }", value.toString());
}
}
}
private static String toString(Map<?, ?> source) {
return iterableToDelimitedString(source.entrySet(), "{ ", " }", new Converter<Entry<?, ?>, Object>() {
public Object convert(Entry<?, ?> source) {
return String.format("\"%s\" : %s", source.getKey(), serializeToJsonSafely(source.getValue()));
}
});
}
private static String toString(Collection<?> source) {
return iterableToDelimitedString(source, "[ ", " ]", new Converter<Object, Object>() {
public Object convert(Object source) {
return serializeToJsonSafely(source);
}
});
}
/**
* Creates a string representation from the given {@link Iterable} prepending the postfix, applying the given
* {@link Converter} to each element before adding it to the result {@link String}, concatenating each element with
* {@literal ,} and applying the postfix.
*
* @param source
* @param prefix
* @param postfix
* @param transformer
* @return
*/
private static <T> String iterableToDelimitedString(Iterable<T> source, String prefix, String postfix,
Converter<? super T, Object> transformer) {
StringBuilder builder = new StringBuilder(prefix);
Iterator<T> iterator = source.iterator();
while (iterator.hasNext()) {
builder.append(transformer.convert(iterator.next()));
if (iterator.hasNext()) {
builder.append(", ");
}
}
return builder.append(postfix).toString();
}
}