Query DSL: fix support for _name in some queries

Some of our Java api builders had wrong logic when it comes to serializing the query in json format, resulting in missing fields like _name. Also, regexp parser was ignoring the _name field.

Closes #11694

core/src/main/java/org/elasticsearch/index/query/FuzzyQueryBuilder.java

@@ -105,9 +105,6 @@ public class FuzzyQueryBuilder extends MultiTermQueryBuilder implements Boostabl
     @Override
     public void doXContent(XContentBuilder builder, Params params) throws IOException {
         builder.startObject(FuzzyQueryParser.NAME);
-        if (boost == -1 && fuzziness == null && prefixLength == null && queryName != null) {
-            builder.field(name, value);
-        } else {
         builder.startObject(name);
         builder.field("value", value);
         if (boost != -1) {
@@ -132,7 +129,6 @@ public class FuzzyQueryBuilder extends MultiTermQueryBuilder implements Boostabl
             builder.field("_name", queryName);
         }
         builder.endObject();
-        }
         builder.endObject();
     }
 }

core/src/main/java/org/elasticsearch/index/query/PrefixQueryBuilder.java

@@ -75,7 +75,7 @@ public class PrefixQueryBuilder extends MultiTermQueryBuilder implements Boostab
     @Override
     public void doXContent(XContentBuilder builder, Params params) throws IOException {
         builder.startObject(PrefixQueryParser.NAME);
-        if (boost == -1 && rewrite == null && queryName != null) {
+        if (boost == -1 && rewrite == null && queryName == null) {
             builder.field(name, prefix);
         } else {
             builder.startObject(name);

core/src/main/java/org/elasticsearch/index/query/RegexpQueryBuilder.java

@@ -98,9 +98,6 @@ public class RegexpQueryBuilder extends MultiTermQueryBuilder implements Boostab
     @Override
     public void doXContent(XContentBuilder builder, Params params) throws IOException {
         builder.startObject(RegexpQueryParser.NAME);
-        if (boost == -1 && rewrite == null && queryName != null) {
-            builder.field(name, regexp);
-        } else {
         builder.startObject(name);
         builder.field("value", regexp);
         if (flags != -1) {
@@ -116,10 +113,9 @@ public class RegexpQueryBuilder extends MultiTermQueryBuilder implements Boostab
             builder.field("rewrite", rewrite);
         }
         if (queryName != null) {
-                builder.field("name", queryName);
+            builder.field("_name", queryName);
         }
         builder.endObject();
-        }
         builder.endObject();
     }
 }

core/src/main/java/org/elasticsearch/index/query/RegexpQueryParser.java

@@ -27,7 +27,6 @@ import org.apache.lucene.util.automaton.Operations;
 import org.elasticsearch.common.inject.Inject;
 import org.elasticsearch.common.lucene.BytesRefs;
 import org.elasticsearch.common.xcontent.XContentParser;
-import org.elasticsearch.index.mapper.FieldMapper;
 import org.elasticsearch.index.mapper.MappedFieldType;
 import org.elasticsearch.index.query.support.QueryParsers;
 
@@ -87,6 +86,8 @@ public class RegexpQueryParser implements QueryParser {
                             maxDeterminizedStates = parser.intValue();
                         } else if ("flags_value".equals(currentFieldName)) {
                             flagsValue = parser.intValue();
+                        } else if ("_name".equals(currentFieldName)) {
+                            queryName = parser.text();
                         } else {
                             throw new QueryParsingException(parseContext, "[regexp] query does not support [" + currentFieldName + "]");
                         }

core/src/main/java/org/elasticsearch/index/query/SpanFirstQueryBuilder.java

@@ -62,7 +62,7 @@ public class SpanFirstQueryBuilder extends SpanQueryBuilder implements Boostable
             builder.field("boost", boost);
         }
         if (queryName != null) {
-            builder.field("name", queryName);
+            builder.field("_name", queryName);
         }
         builder.endObject();
     }

core/src/main/java/org/elasticsearch/index/query/WildcardQueryBuilder.java

@@ -85,7 +85,7 @@ public class WildcardQueryBuilder extends MultiTermQueryBuilder implements Boost
     @Override
     public void doXContent(XContentBuilder builder, Params params) throws IOException {
         builder.startObject(WildcardQueryParser.NAME);
-        if (boost == -1 && rewrite == null && queryName != null) {
+        if (boost == -1 && rewrite == null && queryName == null) {
             builder.field(name, wildcard);
         } else {
             builder.startObject(name);

core/src/test/java/org/elasticsearch/search/matchedqueries/MatchedQueriesTests.java

@@ -21,6 +21,7 @@ package org.elasticsearch.search.matchedqueries;
 
 import org.elasticsearch.action.search.SearchResponse;
 import org.elasticsearch.index.query.QueryBuilder;
+import org.elasticsearch.index.query.QueryBuilders;
 import org.elasticsearch.search.SearchHit;
 import org.elasticsearch.test.ElasticsearchIntegrationTest;
 import org.junit.Test;
@@ -204,6 +205,116 @@ public class MatchedQueriesTests extends ElasticsearchIntegrationTest {
         }
     }
 
+    @Test
+    public void testRegExpQuerySupportsName() {
+        createIndex("test1");
+        ensureGreen();
+
+        client().prepareIndex("test1", "type1", "1").setSource("title", "title1").get();
+        refresh();
+
+        SearchResponse searchResponse = client().prepareSearch()
+                .setQuery(QueryBuilders.regexpQuery("title", "title1").queryName("regex")).get();
+        assertHitCount(searchResponse, 1l);
+
+        for (SearchHit hit : searchResponse.getHits()) {
+            if (hit.id().equals("1")) {
+                assertThat(hit.matchedQueries().length, equalTo(1));
+                assertThat(hit.matchedQueries(), hasItemInArray("regex"));
+            } else {
+                fail("Unexpected document returned with id " + hit.id());
+            }
+        }
+    }
+
+    @Test
+    public void testPrefixQuerySupportsName() {
+        createIndex("test1");
+        ensureGreen();
+
+        client().prepareIndex("test1", "type1", "1").setSource("title", "title1").get();
+        refresh();
+
+        SearchResponse searchResponse = client().prepareSearch()
+                .setQuery(QueryBuilders.prefixQuery("title", "title").queryName("prefix")).get();
+        assertHitCount(searchResponse, 1l);
+
+        for (SearchHit hit : searchResponse.getHits()) {
+            if (hit.id().equals("1")) {
+                assertThat(hit.matchedQueries().length, equalTo(1));
+                assertThat(hit.matchedQueries(), hasItemInArray("prefix"));
+            } else {
+                fail("Unexpected document returned with id " + hit.id());
+            }
+        }
+    }
+
+    @Test
+    public void testFuzzyQuerySupportsName() {
+        createIndex("test1");
+        ensureGreen();
+
+        client().prepareIndex("test1", "type1", "1").setSource("title", "title1").get();
+        refresh();
+
+        SearchResponse searchResponse = client().prepareSearch()
+                .setQuery(QueryBuilders.fuzzyQuery("title", "titel1").queryName("fuzzy")).get();
+        assertHitCount(searchResponse, 1l);
+
+        for (SearchHit hit : searchResponse.getHits()) {
+            if (hit.id().equals("1")) {
+                assertThat(hit.matchedQueries().length, equalTo(1));
+                assertThat(hit.matchedQueries(), hasItemInArray("fuzzy"));
+            } else {
+                fail("Unexpected document returned with id " + hit.id());
+            }
+        }
+    }
+
+    @Test
+    public void testWildcardQuerySupportsName() {
+        createIndex("test1");
+        ensureGreen();
+
+        client().prepareIndex("test1", "type1", "1").setSource("title", "title1").get();
+        refresh();
+
+        SearchResponse searchResponse = client().prepareSearch()
+                .setQuery(QueryBuilders.wildcardQuery("title", "titl*").queryName("wildcard")).get();
+        assertHitCount(searchResponse, 1l);
+
+        for (SearchHit hit : searchResponse.getHits()) {
+            if (hit.id().equals("1")) {
+                assertThat(hit.matchedQueries().length, equalTo(1));
+                assertThat(hit.matchedQueries(), hasItemInArray("wildcard"));
+            } else {
+                fail("Unexpected document returned with id " + hit.id());
+            }
+        }
+    }
+
+    @Test
+    public void testSpanFirstQuerySupportsName() {
+        createIndex("test1");
+        ensureGreen();
+
+        client().prepareIndex("test1", "type1", "1").setSource("title", "title1 title2").get();
+        refresh();
+
+        SearchResponse searchResponse = client().prepareSearch()
+                .setQuery(QueryBuilders.spanFirstQuery(QueryBuilders.spanTermQuery("title", "title1"), 10).queryName("span")).get();
+        assertHitCount(searchResponse, 1l);
+
+        for (SearchHit hit : searchResponse.getHits()) {
+            if (hit.id().equals("1")) {
+                assertThat(hit.matchedQueries().length, equalTo(1));
+                assertThat(hit.matchedQueries(), hasItemInArray("span"));
+            } else {
+                fail("Unexpected document returned with id " + hit.id());
+            }
+        }
+    }
+
     /**
      * Test case for issue #4361: https://github.com/elasticsearch/elasticsearch/issues/4361
      */