Add "did you mean" to unknown queries

modules/lang-mustache/src/test/resources/rest-api-spec/test/lang_mustache/50_multi_search_template.yml

@@ -100,7 +100,7 @@ setup:
   - match:  { responses.1.error.root_cause.0.reason: "/Unexpected.end.of.input/" }
   - match:  { responses.2.hits.total:     1  }
   - match:  { responses.3.error.root_cause.0.type: parsing_exception }
-  - match:  { responses.3.error.root_cause.0.reason: "/no.\\[query\\].registered.for.\\[unknown\\]/" }
+  - match:  { responses.3.error.root_cause.0.reason: "/unknown.query.\\[unknown\\]/" }
 
 ---
 "Multi-search template with invalid request":

rest-api-spec/src/main/resources/rest-api-spec/test/indices.validate_query/10_basic.yml

@@ -43,7 +43,17 @@ setup:
             invalid_query: {}
 
   - is_false: valid
-  - match: {error: 'org.elasticsearch.common.ParsingException: no [query] registered for [invalid_query]'}
+  - match: {error: '/.+unknown\squery\s\[invalid_query\].+/' }
+
+  - do:
+      indices.validate_query:
+        explain: true
+        body:
+          query:
+            boool: {}
+
+  - is_false: valid
+  - match: {error: '/.+unknown\squery\s\[boool\]\sdid\syou\smean\s\[bool\]\?.+/' }
 
   - do:
       indices.validate_query:

server/src/main/java/org/elasticsearch/common/xcontent/SuggestingErrorOnUnknown.java

@@ -32,7 +32,19 @@
 public class SuggestingErrorOnUnknown implements ErrorOnUnknown {
     @Override
     public String errorMessage(String parserName, String unknownField, Iterable<String> candidates) {
-        String message = String.format(Locale.ROOT, "[%s] unknown field [%s]", parserName, unknownField);
+        return String.format(Locale.ROOT, "[%s] unknown field [%s]%s", parserName, unknownField, suggest(unknownField, candidates));
+    }
+
+    @Override
+    public int priority() {
+        return 0;
+    }
+
+    /**
+     * Builds suggestions for an unknown field, returning an empty string if there
+     * aren't any suggestions or " did you mean " and then the list of suggestions. 
+     */
+    public static String suggest(String unknownField, Iterable<String> candidates) {
         // TODO it'd be nice to combine this with BaseRestHandler's implementation.
         LevenshteinDistance ld = new LevenshteinDistance();
         final List<Tuple<Float, String>> scored = new ArrayList<>();
@@ -43,7 +55,7 @@ public String errorMessage(String parserName, String unknownField, Iterable<Stri
             }
         }
         if (scored.isEmpty()) {
-            return message;
+            return "";
         }
         CollectionUtil.timSort(scored, (a, b) -> {
             // sort by distance in reverse order, then parameter name for equal distances
@@ -54,7 +66,7 @@ public String errorMessage(String parserName, String unknownField, Iterable<Stri
             return a.v2().compareTo(b.v2());
         });
         List<String> keys = scored.stream().map(Tuple::v2).collect(toList());
-        StringBuilder builder = new StringBuilder(message).append(" did you mean ");
+        StringBuilder builder = new StringBuilder(" did you mean ");
         if (keys.size() == 1) {
             builder.append("[").append(keys.get(0)).append("]");
         } else {
@@ -63,9 +75,4 @@ public String errorMessage(String parserName, String unknownField, Iterable<Stri
         builder.append("?");
         return builder.toString();
     }
-
-    @Override
-    public int priority() {
-        return 0;
-    }
 }

server/src/main/java/org/elasticsearch/index/query/AbstractQueryBuilder.java

@@ -32,6 +32,7 @@
 import org.elasticsearch.common.lucene.BytesRefs;
 import org.elasticsearch.common.xcontent.AbstractObjectParser;
 import org.elasticsearch.common.xcontent.NamedObjectNotFoundException;
+import org.elasticsearch.common.xcontent.SuggestingErrorOnUnknown;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentLocation;
 import org.elasticsearch.common.xcontent.XContentParser;
@@ -41,6 +42,7 @@
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 
@@ -313,10 +315,9 @@ public static QueryBuilder parseInnerQueryBuilder(XContentParser parser) throws
         try {
             result = parser.namedObject(QueryBuilder.class, queryName, null);
         } catch (NamedObjectNotFoundException e) {
-            // Preserve the error message from 5.0 until we have a compellingly better message so we don't break BWC.
-            // This intentionally doesn't include the causing exception because that'd change the "root_cause" of any unknown query errors
-            throw new ParsingException(new XContentLocation(e.getLineNumber(), e.getColumnNumber()),
-                    "no [query] registered for [" + queryName + "]");
+            String message = String.format(Locale.ROOT, "unknown query [%s]%s", queryName,
+                    SuggestingErrorOnUnknown.suggest(queryName, e.getCandidates()));
+            throw new ParsingException(new XContentLocation(e.getLineNumber(), e.getColumnNumber()), message, e);
         }
         //end_object of the specific query (e.g. match, multi_match etc.) element
         if (parser.currentToken() != XContentParser.Token.END_OBJECT) {

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

@@ -78,10 +78,15 @@ public void testParseInnerQueryBuilderExceptions() throws IOException {
             assertEquals("[foo] query malformed, no start_object after query name", exception.getMessage());
         }
 
-        source = "{ \"foo\" : {} }";
+        source = "{ \"boool\" : {} }";
         try (XContentParser parser = createParser(JsonXContent.jsonXContent, source)) {
             ParsingException exception = expectThrows(ParsingException.class, () ->  parseInnerQueryBuilder(parser));
-            assertEquals("no [query] registered for [foo]", exception.getMessage());
+            assertEquals("unknown query [boool] did you mean [bool]?", exception.getMessage());
+        }
+        source = "{ \"match_\" : {} }";
+        try (XContentParser parser = createParser(JsonXContent.jsonXContent, source)) {
+            ParsingException exception = expectThrows(ParsingException.class, () ->  parseInnerQueryBuilder(parser));
+            assertEquals("unknown query [match_] did you mean any of [match, match_all, match_none]?", exception.getMessage());
         }
     }
 

x-pack/plugin/src/test/resources/rest-api-spec/test/watcher/execute_watch/20_transform.yml

@@ -188,5 +188,5 @@ setup:
   - match: { watch_record.state: "executed" }
   - match: { watch_record.status.execution_state: "executed" }
   - match: { watch_record.result.transform.status: "failure" }
-  - match: { watch_record.result.transform.reason: "no [query] registered for [does_not_exist]" }
+  - match: { watch_record.result.transform.reason: "unknown query [does_not_exist]" }
   - is_true: watch_record.result.transform.error