PassThroughObject nests aliases within objects for fields with dotted…

… names (#105298) * Ignore duplicate FieldAliasMappers during building * Update docs/changelog/105298.yaml * revert * nest alias within objects * Delete docs/changelog/105298.yaml
elastic · Feb 9, 2024 · f65312e · f65312e
1 parent 8c9c24c
commit f65312e
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Showing 3 changed files with 30 additions and 6 deletions.
diff --git a/server/src/main/java/org/elasticsearch/index/mapper/ObjectMapper.java b/server/src/main/java/org/elasticsearch/index/mapper/ObjectMapper.java
@@ -317,7 +317,7 @@ protected static void parseProperties(
                         throw new MapperParsingException("No handler for type [" + type + "] declared on field [" + fieldName + "]");
                     }
                     Mapper.Builder fieldBuilder;
-                    if (objBuilder.subobjects.value() == false || type.equals(FieldAliasMapper.CONTENT_TYPE)) {
+                    if (objBuilder.subobjects.value() == false) {
                         fieldBuilder = typeParser.parse(fieldName, propNode, parserContext);
                     } else {
                         String[] fieldNameParts = fieldName.split("\\.");

diff --git a/server/src/main/java/org/elasticsearch/index/mapper/RootObjectMapper.java b/server/src/main/java/org/elasticsearch/index/mapper/RootObjectMapper.java
@@ -155,10 +155,34 @@ void getAliasMappers(Map<String, Mapper> mappers, Map<String, Mapper> aliasMappe
                                     );
                                 }
                             } else {
-                                FieldAliasMapper aliasMapper = new FieldAliasMapper.Builder(fieldMapper.simpleName()).path(
-                                    fieldMapper.mappedFieldType.name()
-                                ).build(context);
-                                aliasMappers.put(aliasMapper.simpleName(), aliasMapper);
+                                // Check if the field name contains dots, as aliases require nesting within objects in this case.
+                                String[] fieldNameParts = fieldMapper.simpleName().split("\\.");
+                                if (fieldNameParts.length == 0) {
+                                    throw new IllegalArgumentException("field name cannot contain only dots");
+                                }
+                                if (fieldNameParts.length == 1) {
+                                    // No nesting required, add the alias directly to the root.
+                                    FieldAliasMapper aliasMapper = new FieldAliasMapper.Builder(fieldMapper.simpleName()).path(
+                                        fieldMapper.mappedFieldType.name()
+                                    ).build(context);
+                                    aliasMappers.put(aliasMapper.simpleName(), aliasMapper);
+                                } else {
+                                    // Nest the alias within object(s).
+                                    String realFieldName = fieldNameParts[fieldNameParts.length - 1];
+                                    Mapper.Builder fieldBuilder = new FieldAliasMapper.Builder(realFieldName).path(
+                                        fieldMapper.mappedFieldType.name()
+                                    );
+                                    for (int i = fieldNameParts.length - 2; i >= 0; --i) {
+                                        String intermediateObjectName = fieldNameParts[i];
+                                        ObjectMapper.Builder intermediate = new ObjectMapper.Builder(
+                                            intermediateObjectName,
+                                            ObjectMapper.Defaults.SUBOBJECTS
+                                        );
+                                        intermediate.add(fieldBuilder);
+                                        fieldBuilder = intermediate;
+                                    }
+                                    aliasMappers.put(fieldNameParts[0], fieldBuilder.build(context));
+                                }
                             }
                         }
                     }

diff --git a/server/src/test/java/org/elasticsearch/index/mapper/RootObjectMapperTests.java b/server/src/test/java/org/elasticsearch/index/mapper/RootObjectMapperTests.java
@@ -387,7 +387,7 @@ public void testPassThroughObjectNested() throws IOException {
         }));
         assertThat(mapperService.mappingLookup().getMapper("dim"), instanceOf(FieldAliasMapper.class));
         assertThat(mapperService.mappingLookup().getMapper("resource.attributes.dim"), instanceOf(KeywordFieldMapper.class));
-        assertThat(mapperService.mappingLookup().getMapper("another.dim"), instanceOf(FieldAliasMapper.class));
+        assertThat(mapperService.mappingLookup().objectMappers().get("another").getMapper("dim"), instanceOf(FieldAliasMapper.class));
         assertThat(mapperService.mappingLookup().getMapper("attributes.another.dim"), instanceOf(KeywordFieldMapper.class));
     }