Allow MappedFieldType impls to hide themselves from field caps

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

@@ -8,6 +8,12 @@ setup:
                 properties:
                   text:
                     type:     text
+                  text_with_subs:
+                    type:     text
+                    index_prefixes:
+                      min_chars: 2
+                      max_chars: 3
+                    index_phrases: true
                   keyword:
                     type:     keyword
                   number:
@@ -316,3 +322,18 @@ setup:
   - match: {fields.misc.unmapped.searchable:            false}
   - match: {fields.misc.unmapped.aggregatable:          false}
   - match: {fields.misc.unmapped.indices:               ["test2", "test3"]}
+
+---
+"Field caps exclude text implementation subfields":
+  - skip:
+      version: " - 8.0.0"
+      reason: subfields excluded in 7.11
+
+  - do:
+      field_caps:
+        index: 'test1,test2,test3'
+        fields: [ text_with_subs ]
+
+  - match: { fields.text_with_subs: true }
+  - match: { fields.text_with_subs._index_prefix: false }
+  - match: { fields.text_with_subs._index_phrase: false }

server/src/main/java/org/elasticsearch/action/fieldcaps/IndexFieldCapabilities.java

@@ -48,9 +48,9 @@ public class IndexFieldCapabilities implements Writeable {
      * @param isAggregatable Whether this field can be aggregated on.
      * @param meta Metadata about the field.
      */
-    IndexFieldCapabilities(String name, String type,
-                           boolean isSearchable, boolean isAggregatable,
-                           Map<String, String> meta) {
+    public IndexFieldCapabilities(String name, String type,
+                                  boolean isSearchable, boolean isAggregatable,
+                                  Map<String, String> meta) {
 
         this.name = name;
         this.type = type;

server/src/main/java/org/elasticsearch/action/fieldcaps/TransportFieldCapabilitiesIndexAction.java

@@ -124,8 +124,10 @@ private FieldCapabilitiesIndexResponse shardOperation(final FieldCapabilitiesInd
             if (ft != null) {
                 if (indicesService.isMetadataField(mapperService.getIndexSettings().getIndexVersionCreated(), field)
                     || fieldPredicate.test(ft.name())) {
-                    IndexFieldCapabilities fieldCap = new IndexFieldCapabilities(field, ft.familyTypeName(),
-                        ft.isSearchable(), ft.isAggregatable(), ft.meta());
+                    IndexFieldCapabilities fieldCap = ft.fieldCaps();
+                    if (fieldCap == null) {
+                        continue;
+                    }
                     responseMap.put(field, fieldCap);
                 } else {
                     continue;

server/src/main/java/org/elasticsearch/index/mapper/MappedFieldType.java

@@ -39,6 +39,7 @@
 import org.apache.lucene.search.spans.SpanQuery;
 import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.ElasticsearchParseException;
+import org.elasticsearch.action.fieldcaps.IndexFieldCapabilities;
 import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.geo.ShapeRelation;
 import org.elasticsearch.common.time.DateMathParser;
@@ -111,6 +112,16 @@ public String familyTypeName() {
         return typeName();
     }
 
+    /**
+     * Returns the capabilities of this field.
+     *
+     * If the field should not be returned as part of a Field Capabilities call,
+     * implementations can return {@code null}
+     */
+    public IndexFieldCapabilities fieldCaps() {
+        return new IndexFieldCapabilities(name, familyTypeName(), isSearchable(), isAggregatable(), meta);
+    }
+
     public String name() {
         return name;
     }

server/src/main/java/org/elasticsearch/index/mapper/TextFieldMapper.java

@@ -57,6 +57,7 @@
 import org.apache.lucene.util.automaton.Automaton;
 import org.apache.lucene.util.automaton.Operations;
 import org.elasticsearch.Version;
+import org.elasticsearch.action.fieldcaps.IndexFieldCapabilities;
 import org.elasticsearch.common.collect.Iterators;
 import org.elasticsearch.common.lucene.Lucene;
 import org.elasticsearch.common.lucene.search.AutomatonQueries;
@@ -459,6 +460,11 @@ void setAnalyzer(String name, Analyzer delegate) {
             setIndexAnalyzer(new NamedAnalyzer(name, AnalyzerScope.INDEX, new PhraseWrappedAnalyzer(delegate)));
         }
 
+        @Override
+        public IndexFieldCapabilities fieldCaps() {
+            return null;    // don't show impl sub-fields in fieldcaps
+        }
+
         @Override
         public String typeName() {
             return "phrase";
@@ -492,6 +498,11 @@ static final class PrefixFieldType extends StringFieldType {
             this.parentField = parentField;
         }
 
+        @Override
+        public IndexFieldCapabilities fieldCaps() {
+            return null;    // don't show impl subfields in field caps
+        }
+
         @Override
         public ValueFetcher valueFetcher(MapperService mapperService, SearchLookup searchLookup, String format) {
             throw new UnsupportedOperationException();