Removing _doc from data stream effective mappings

Author: masseyke

modules/data-streams/src/yamlRestTest/resources/rest-api-spec/test/data_stream/250_data_stream_mappings.yml

@@ -34,7 +34,7 @@ setup:
         name: my-data-stream-1
   - match: { data_streams.0.name: my-data-stream-1 }
   - match: { data_streams.0.mappings: {} }
-  - length: { data_streams.0.effective_mappings._doc.properties: 2 }
+  - length: { data_streams.0.effective_mappings.properties: 2 }
 
   - do:
       indices.get_data_stream:
@@ -56,7 +56,7 @@ setup:
   - match: { data_streams.0.name: my-data-stream-1 }
   - match: { data_streams.0.applied_to_data_stream: true }
   - match: { data_streams.0.mappings.properties.name.type: "keyword" }
-  - match: { data_streams.0.effective_mappings._doc.properties.name.type: "keyword" }
+  - match: { data_streams.0.effective_mappings.properties.name.type: "keyword" }
 
   - do:
       indices.rollover:
@@ -71,9 +71,9 @@ setup:
       indices.get_data_stream_mappings:
         name: my-data-stream-1
   - match: { data_streams.0.name: my-data-stream-1 }
-  - length: { data_streams.0.effective_mappings._doc.properties: 3 }
+  - length: { data_streams.0.effective_mappings.properties: 3 }
   - match: { data_streams.0.mappings.properties.name.type: "keyword" }
-  - match: { data_streams.0.effective_mappings._doc.properties.name.type: "keyword" }
+  - match: { data_streams.0.effective_mappings.properties.name.type: "keyword" }
 
   - do:
       indices.get_data_stream:
@@ -149,9 +149,9 @@ setup:
   - match: { data_streams.0.mappings.properties.field1.type: "text" }
   - match: { data_streams.0.mappings.properties.field2: null }
   - match: { data_streams.0.mappings.properties.field3.type: "text" }
-  - match: { data_streams.0.effective_mappings._doc.properties.field1.type: "text" }
-  - match: { data_streams.0.effective_mappings._doc.properties.field2.type: "keyword" }
-  - match: { data_streams.0.effective_mappings._doc.properties.field3.type: "text" }
+  - match: { data_streams.0.effective_mappings.properties.field1.type: "text" }
+  - match: { data_streams.0.effective_mappings.properties.field2.type: "keyword" }
+  - match: { data_streams.0.effective_mappings.properties.field3.type: "text" }
 
   - do:
       cluster.put_component_template:
@@ -180,10 +180,10 @@ setup:
       indices.get_data_stream_mappings:
         name: my-component-only-data-stream-1
   - match: { data_streams.0.name: my-component-only-data-stream-1 }
-  - length: { data_streams.0.effective_mappings._doc.properties: 5 }
+  - length: { data_streams.0.effective_mappings.properties: 5 }
   - match: { data_streams.0.mappings.properties.field1.type: "text" }
-  - match: { data_streams.0.effective_mappings._doc.properties.field3.type: "text" }
-  - match: { data_streams.0.effective_mappings._doc.properties.field4.type: "keyword" }
+  - match: { data_streams.0.effective_mappings.properties.field3.type: "text" }
+  - match: { data_streams.0.effective_mappings.properties.field4.type: "keyword" }
 
   - do:
       indices.get_data_stream:
@@ -212,7 +212,7 @@ setup:
   - match: { data_streams.0.name: my-component-only-data-stream-1 }
   - match: { data_streams.0.applied_to_data_stream: true }
   - match: { data_streams.0.mappings null }
-  - match: { data_streams.0.effective_mappings._doc.properties.field1.type: "keyword" }
-  - match: { data_streams.0.effective_mappings._doc.properties.field2.type: "keyword" }
-  - match: { data_streams.0.effective_mappings._doc.properties.field3: null }
-  - match: { data_streams.0.effective_mappings._doc.properties.field4.type: "keyword" }
+  - match: { data_streams.0.effective_mappings.properties.field1.type: "keyword" }
+  - match: { data_streams.0.effective_mappings.properties.field2.type: "keyword" }
+  - match: { data_streams.0.effective_mappings.properties.field3: null }
+  - match: { data_streams.0.effective_mappings.properties.field4.type: "keyword" }

server/src/main/java/org/elasticsearch/cluster/metadata/DataStream.java

@@ -46,7 +46,6 @@
 import org.elasticsearch.index.IndexMode;
 import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.mapper.DateFieldMapper;
-import org.elasticsearch.index.mapper.DocumentMapper;
 import org.elasticsearch.index.mapper.MapperService;
 import org.elasticsearch.indices.IndicesService;
 import org.elasticsearch.indices.SystemIndices;
@@ -500,13 +499,20 @@ public static CompressedXContent getEffectiveMappings(
             writeIndex.getName()
         );
         return indicesService.withTempIndexService(projectMetadata.index(writeIndex), indexService -> {
-            MapperService mapperService = indexService.mapperService();
-            DocumentMapper documentMapper = mapperService.merge(
-                MapperService.SINGLE_MAPPING_NAME,
-                mappings,
-                MapperService.MergeReason.INDEX_TEMPLATE
-            );
-            return documentMapper.mappingSource();
+            CompressedXContent mergedMapping = indexService.mapperService()
+                .merge(MapperService.SINGLE_MAPPING_NAME, mappings, MapperService.MergeReason.INDEX_TEMPLATE)
+                .mappingSource();
+            /*
+             * If the merged mapping contains the old "_doc" type placeholder, we remove it to make things more straightforward for the
+             * client:
+             */
+            Map<String, Object> mergedMappingMap = XContentHelper.convertToMap(mergedMapping.uncompressed(), true, XContentType.JSON).v2();
+            if (mergedMappingMap.containsKey(MapperService.SINGLE_MAPPING_NAME)) {
+                mergedMapping = ComposableIndexTemplate.convertMappingMapToXContent(
+                    (Map<String, ?>) mergedMappingMap.get(MapperService.SINGLE_MAPPING_NAME)
+                );
+            }
+            return mergedMapping;
         });
     }