Fix alias field resolution in match query (#47369)

Synonym queries (when two tokens/paths start at the same position) use the alias field instead
of the concrete field to build Lucene queries. This commit fixes this bug by resolving the alias field upfront in order to provide the concrete field to the actual query parser.

Author: jimczi

server/src/main/java/org/elasticsearch/index/search/MatchQuery.java

@@ -62,6 +62,7 @@
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Set;
 import java.util.function.Supplier;
 
 import static org.elasticsearch.common.lucene.search.Queries.newLenientFieldQuery;
@@ -248,6 +249,14 @@ public Query parse(Type type, String fieldName, Object value) throws IOException
         if (fieldType == null) {
             return newUnmappedFieldQuery(fieldName);
         }
+        Set<String> fields = context.simpleMatchToIndexNames(fieldName);
+        if (fields.contains(fieldName)) {
+            assert fields.size() == 1;
+            // this field is a concrete field or an alias so we use the
+            // field type name directly
+            fieldName = fieldType.name();
+        }
+
         Analyzer analyzer = getAnalyzer(fieldType, type == Type.PHRASE || type == Type.PHRASE_PREFIX);
         assert analyzer != null;
 
@@ -261,9 +270,9 @@ public Query parse(Type type, String fieldName, Object value) throws IOException
          */
         if (analyzer == Lucene.KEYWORD_ANALYZER && type != Type.PHRASE_PREFIX) {
             final Term term = new Term(fieldName, value.toString());
-            if ((fieldType instanceof TextFieldMapper.TextFieldType || fieldType instanceof KeywordFieldMapper.KeywordFieldType)
-                && type == Type.BOOLEAN_PREFIX) {
-                return builder.newPrefixQuery(fieldName, term);
+            if (type == Type.BOOLEAN_PREFIX
+                    && (fieldType instanceof TextFieldMapper.TextFieldType || fieldType instanceof KeywordFieldMapper.KeywordFieldType)) {
+                return builder.newPrefixQuery(term);
             } else {
                 return builder.newTermQuery(term);
             }
@@ -581,12 +590,12 @@ protected Query newTermQuery(Term term) {
         /**
          * Builds a new prefix query instance.
          */
-        protected Query newPrefixQuery(String field, Term term) {
+        protected Query newPrefixQuery(Term term) {
             try {
                 return fieldType.prefixQuery(term.text(), null, context);
             } catch (RuntimeException e) {
                 if (lenient) {
-                    return newLenientFieldQuery(field, e);
+                    return newLenientFieldQuery(term.field(), e);
                 }
                 throw e;
             }
@@ -603,7 +612,7 @@ private Query analyzeTerm(String field, TokenStream stream, boolean isPrefix) th
             final Term term = new Term(field, termAtt.getBytesRef());
             int lastOffset = offsetAtt.endOffset();
             stream.end();
-            return isPrefix && lastOffset == offsetAtt.endOffset() ? newPrefixQuery(field, term) : newTermQuery(term);
+            return isPrefix && lastOffset == offsetAtt.endOffset() ? newPrefixQuery(term) : newTermQuery(term);
         }
 
         private void add(BooleanQuery.Builder q, String field, List<Term> current, BooleanClause.Occur operator, boolean isPrefix) {
@@ -612,7 +621,7 @@ private void add(BooleanQuery.Builder q, String field, List<Term> current, Boole
             }
             if (current.size() == 1) {
                 if (isPrefix) {
-                    q.add(newPrefixQuery(field, current.get(0)), operator);
+                    q.add(newPrefixQuery(current.get(0)), operator);
                 } else {
                     q.add(newTermQuery(current.get(0)), operator);
                 }
@@ -729,7 +738,7 @@ public Query next() {
                     Term[] terms = graph.getTerms(field, start);
                     assert terms.length > 0;
                     if (terms.length == 1) {
-                        queryPos = usePrefix ? newPrefixQuery(field, terms[0]) : newTermQuery(terms[0]);
+                        queryPos = usePrefix ? newPrefixQuery(terms[0]) : newTermQuery(terms[0]);
                     } else {
                         // We don't apply prefix on synonyms
                         queryPos = newSynonymQuery(terms);

server/src/main/java/org/elasticsearch/index/search/MultiMatchQuery.java

@@ -194,7 +194,7 @@ protected Query newTermQuery(Term term) {
         }
 
         @Override
-        protected Query newPrefixQuery(String field, Term term) {
+        protected Query newPrefixQuery(Term term) {
             List<Query> disjunctions = new ArrayList<>();
             for (FieldAndBoost fieldType : blendedFields) {
                 Query query = fieldType.fieldType.prefixQuery(term.text(), null, context);

server/src/main/java/org/elasticsearch/index/search/QueryParserHelper.java

@@ -52,7 +52,7 @@ public static Map<String, Float> parseFieldsAndWeights(List<String> fields) {
             float boost = 1.0f;
             if (boostIndex != -1) {
                 fieldName = field.substring(0, boostIndex);
-                boost = Float.parseFloat(field.substring(boostIndex+1, field.length()));
+                boost = Float.parseFloat(field.substring(boostIndex+1));
             } else {
                 fieldName = field;
             }

server/src/test/java/org/elasticsearch/index/query/MatchQueryBuilderTests.java

@@ -32,6 +32,7 @@
 import org.apache.lucene.search.PhraseQuery;
 import org.apache.lucene.search.PointRangeQuery;
 import org.apache.lucene.search.Query;
+import org.apache.lucene.search.SynonymQuery;
 import org.apache.lucene.search.TermQuery;
 import org.apache.lucene.search.spans.SpanNearQuery;
 import org.apache.lucene.search.spans.SpanOrQuery;
@@ -490,6 +491,18 @@ public void testMultiWordSynonymsPhrase() throws Exception {
         assertEquals(expected, actual);
     }
 
+
+    public void testAliasWithSynonyms() throws Exception {
+        final MatchQuery matchQuery = new MatchQuery(createShardContext());
+        matchQuery.setAnalyzer(new MockSynonymAnalyzer());
+        final Query actual = matchQuery.parse(Type.PHRASE, STRING_ALIAS_FIELD_NAME, "dogs");
+        Query expected = new SynonymQuery.Builder(STRING_FIELD_NAME)
+            .addTerm(new Term(STRING_FIELD_NAME, "dogs"))
+            .addTerm(new Term(STRING_FIELD_NAME, "dog"))
+            .build();
+        assertEquals(expected, actual);
+    }
+
     public void testMaxBooleanClause() {
         MatchQuery query = new MatchQuery(createShardContext());
         query.setAnalyzer(new MockGraphAnalyzer(createGiantGraph(40)));