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Preserve empty objects and arrays when filtering
This change updates our support for filtering so that empty arrays and objects are preserved when they are present in the content that is filtering. Closes elastic#63842
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3 files changed

+133
-4
lines changed

3 files changed

+133
-4
lines changed

‎libs/x-content/src/main/java/org/elasticsearch/common/xcontent/json/JsonXContentGenerator.java

+3-2
Original file line numberDiff line numberDiff line change
@@ -35,6 +35,7 @@
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import org.elasticsearch.common.xcontent.XContentGenerator;
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import org.elasticsearch.common.xcontent.XContentParser;
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import org.elasticsearch.common.xcontent.XContentType;
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import org.elasticsearch.common.xcontent.support.filtering.EmptyPreservingFilteringGeneratorDelegate;
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import org.elasticsearch.common.xcontent.support.filtering.FilterPathBasedFilter;
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import org.elasticsearch.core.internal.io.Streams;
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@@ -86,12 +87,12 @@ public JsonXContentGenerator(JsonGenerator jsonGenerator, OutputStream os, Set<S
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boolean hasExcludes = excludes.isEmpty() == false;
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if (hasExcludes) {
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generator = new FilteringGeneratorDelegate(generator, new FilterPathBasedFilter(excludes, false), true, true);
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generator = new EmptyPreservingFilteringGeneratorDelegate(generator, new FilterPathBasedFilter(excludes, false), true, true);
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}
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boolean hasIncludes = includes.isEmpty() == false;
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if (hasIncludes) {
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generator = new FilteringGeneratorDelegate(generator, new FilterPathBasedFilter(includes, true), true, true);
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generator = new EmptyPreservingFilteringGeneratorDelegate(generator, new FilterPathBasedFilter(includes, true), true, true);
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}
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if (hasExcludes || hasIncludes) {

‎libs/x-content/src/main/java/org/elasticsearch/common/xcontent/support/filtering/EmptyPreservingFilteringGeneratorDelegate.java

+106
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,106 @@
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/*
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* Licensed to Elasticsearch under one or more contributor
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* license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright
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* ownership. Elasticsearch licenses this file to you under
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* the Apache License, Version 2.0 (the "License"); you may
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* 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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* http://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,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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*/
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package org.elasticsearch.common.xcontent.support.filtering;
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import com.fasterxml.jackson.core.JsonGenerator;
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import com.fasterxml.jackson.core.JsonStreamContext;
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import com.fasterxml.jackson.core.filter.FilteringGeneratorDelegate;
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import com.fasterxml.jackson.core.filter.TokenFilter;
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import com.fasterxml.jackson.core.filter.TokenFilterContext;
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import java.io.IOException;
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/**
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* An extension of the Jockson {@link FilteringGeneratorDelegate} that preserves empty objects and
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* empty arrays in the filtered output. This is done by checking values during the close of the
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* array or object inside a custom token filter context.
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*/
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public class EmptyPreservingFilteringGeneratorDelegate extends FilteringGeneratorDelegate {
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public EmptyPreservingFilteringGeneratorDelegate(JsonGenerator generator,
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TokenFilter filter,
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boolean includePath,
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boolean allowMultipleMatches
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) {
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super(generator, filter, includePath, allowMultipleMatches);
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this._filterContext = new EmptyPreservingTokenFilterContext(EmptyPreservingTokenFilterContext.ROOT, null, filter, true);
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}
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static class EmptyPreservingTokenFilterContext extends TokenFilterContext {
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public static final int ROOT = JsonStreamContext.TYPE_ROOT;
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EmptyPreservingTokenFilterContext(int type, TokenFilterContext parent, TokenFilter filter, boolean startHandled) {
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super(type, parent, filter, startHandled);
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}
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@Override
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public TokenFilterContext createChildArrayContext(TokenFilter filter, boolean writeStart) {
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TokenFilterContext ctxt = _child;
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if (ctxt == null) {
58+
_child = ctxt = new EmptyPreservingTokenFilterContext(TYPE_ARRAY, this, filter, writeStart);
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return ctxt;
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}
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return ((EmptyPreservingTokenFilterContext) ctxt).reset(TYPE_ARRAY, filter, writeStart);
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}
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@Override
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public TokenFilterContext createChildObjectContext(TokenFilter filter, boolean writeStart) {
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TokenFilterContext ctxt = _child;
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if (ctxt == null) {
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_child = ctxt = new EmptyPreservingTokenFilterContext(TYPE_OBJECT, this, filter, writeStart);
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return ctxt;
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}
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return ((EmptyPreservingTokenFilterContext) ctxt).reset(TYPE_OBJECT, filter, writeStart);
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}
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@Override
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public TokenFilterContext closeArray(JsonGenerator gen) throws IOException {
76+
if (_startHandled) {
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gen.writeEndArray();
78+
}
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if ((_filter != null) && (_filter != TokenFilter.INCLUDE_ALL)) {
80+
if (_type == TYPE_ARRAY && _index == -1) { // empty
81+
writePath(gen);
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gen.writeEndArray();
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}
84+
_filter.filterFinishArray();
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}
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return _parent;
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}
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@Override
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public TokenFilterContext closeObject(JsonGenerator gen) throws IOException {
91+
if (_startHandled) {
92+
gen.writeEndObject();
93+
}
94+
if ((_filter != null) && (_filter != TokenFilter.INCLUDE_ALL)) {
95+
if (isStartHandled() == false && _child == null && hasCurrentName() == false) {
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// empty!
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_parent.writePath(gen);
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gen.writeStartObject();
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gen.writeEndObject();
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}
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_filter.filterFinishObject();
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}
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return _parent;
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}
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}
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}

‎server/src/test/java/org/elasticsearch/common/xcontent/support/filtering/FilterPathGeneratorFilteringTests.java

+24-2
Original file line numberDiff line numberDiff line change
@@ -167,10 +167,32 @@ public void testExclusiveFiltersWithDots() throws Exception {
167167
assertResult("{'a':0,'b.c':'value','b':{'c':'c_value'}}", "b\\.c", false, "{'a':0,'b':{'c':'c_value'}}");
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}
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public void testWithEmptyArraysAndObjects() throws Exception {
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assertResult("{ 'foo': 'bar', 'hits': [] }", "**.not_there", false, "{'foo':'bar','hits':[]}");
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assertResult("{ 'foo': 'bar', 'hits': {} }", "**.not_there", false, "{'foo':'bar','hits':{}}");
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// only include foo
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assertResult("{ 'foo': 'bar', 'hits': [] }", "foo", true, "{'foo':'bar'}");
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assertResult("{ 'foo': 'bar', 'hits': {} }", "foo", true, "{'foo':'bar'}");
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// exclude the empty values
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assertResult("{ 'foo': 'bar', 'hits': [] }", "hits", false, "{'foo':'bar'}");
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assertResult("{ 'foo': 'bar', 'hits': {} }", "hits", false, "{'foo':'bar'}");
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// empty at non-root level
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assertResult("{ 'foo': 'bar', 'a' : { 'hits': [] } }", "**.not_empty", false, "{'foo':'bar','a':{'hits':[]}}");
184+
assertResult("{ 'foo': 'bar', 'a' : { 'hits': {} } }", "**.not_empty", false, "{'foo':'bar','a':{'hits':{}}}");
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// empty empty at non-root level
187+
assertResult("{ 'foo': 'bar', 'a' : { 'hits': [] } }", "**.hits", false, "{'foo':'bar'}");
188+
assertResult("{ 'foo': 'bar', 'a' : { 'hits': {} } }", "**.hits", false, "{'foo':'bar'}");
189+
}
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private void assertResult(String input, String filter, boolean inclusive, String expected) throws Exception {
171192
try (BytesStreamOutput os = new BytesStreamOutput()) {
172-
try (FilteringGeneratorDelegate generator = new FilteringGeneratorDelegate(JSON_FACTORY.createGenerator(os),
173-
new FilterPathBasedFilter(Collections.singleton(filter), inclusive), true, true)) {
193+
FilterPathBasedFilter pathBasedFilter = new FilterPathBasedFilter(Collections.singleton(filter), inclusive);
194+
try (FilteringGeneratorDelegate generator = new EmptyPreservingFilteringGeneratorDelegate(JSON_FACTORY.createGenerator(os),
195+
pathBasedFilter, true, true)) {
174196
try (JsonParser parser = JSON_FACTORY.createParser(replaceQuotes(input))) {
175197
while (parser.nextToken() != null) {
176198
generator.copyCurrentStructure(parser);

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