empty element name

Author: Japleen Kaur

contrib/babelfishpg_tsql/src/tsql_for/forxml.c

@@ -229,19 +229,34 @@ tsql_row_to_xml_raw(StringInfo state, Datum record, const char *element_name, bo
 	tmptup.t_data = td;
 	tuple = &tmptup;
 
-	/* Output opening tag */
-	if (elements)
+	/*
+	 * Empty element name without ELEMENTS mode is not allowed — attribute-centric
+	 * serialization requires a row tag name.
+	 */
+	if (element_name[0] == '\0' && !elements)
 	{
-		/* ELEMENTS mode: <row><col>value</col></row> */
-		if (xsinil)
-			appendStringInfo(state, "<%s " XML_XMLNS_XSI ">", element_name);
-		else
-			appendStringInfo(state, "<%s>", element_name);
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_XML_PROCESSING_INSTRUCTION),
+				 errmsg("Row tag omission (empty row tag name) cannot be used "
+						"with attribute-centric FOR XML serialization.")));
 	}
-	else
+
+	/* Output opening tag (only when element_name is non-empty) */
+	if (element_name[0] != '\0')
 	{
-		/* ATTRIBUTES mode: <row col="value"/> */
-		appendStringInfo(state, "<%s", element_name);
+		if (elements)
+		{
+			/* ELEMENTS mode: <row><col>value</col></row> */
+			if (xsinil)
+				appendStringInfo(state, "<%s " XML_XMLNS_XSI ">", element_name);
+			else
+				appendStringInfo(state, "<%s>", element_name);
+		}
+		else
+		{
+			/* ATTRIBUTES mode: <row col="value"/> */
+			appendStringInfo(state, "<%s", element_name);
+		}
 	}
 
 	for (int i = 0; i < tupdesc->natts; i++)
@@ -296,7 +311,14 @@ tsql_row_to_xml_raw(StringInfo state, Datum record, const char *element_name, bo
 	/* Output closing tag */
 	if (elements)
 	{
-		if (allnull)
+		if (element_name[0] == '\0')
+		{
+			/*
+			 * Empty element name with ELEMENTS: no wrapper tag needed.
+			 * Just output the child elements directly, same as PATH('').
+			 */
+		}
+		else if (allnull)
 		{
 			/*
 			 * If all column values are NULL, produce a self-closing element

test/JDBC/expected/forxml-raw-elements-vu-verify.out

@@ -143,7 +143,7 @@ SELECT NULL AS a, NULL AS b FOR XML RAW, ELEMENTS;
 GO
 ~~START~~
 ntext
-<row></row>
+<row/>
 ~~END~~
 
 
@@ -170,7 +170,7 @@ SELECT NULL AS a, NULL AS b, NULL AS c, NULL AS d FOR XML RAW, ELEMENTS;
 GO
 ~~START~~
 ntext
-<row></row>
+<row/>
 ~~END~~
 
 
@@ -198,7 +198,7 @@ SELECT NULL AS a, NULL AS b FOR XML RAW, ELEMENTS ABSENT;
 GO
 ~~START~~
 ntext
-<row></row>
+<row/>
 ~~END~~
 
 
@@ -510,7 +510,7 @@ SELECT name, salary FROM forxml_raw_elements_t1 FOR XML RAW, ELEMENTS;
 GO
 ~~START~~
 ntext
-<row><name>John</name><salary>50000</salary></row><row><name>Jane</name><salary>60000</salary></row><row><name>Bob</name></row><row><name>Alice</name><salary>70000</salary></row><row></row>
+<row><name>John</name><salary>50000</salary></row><row><name>Jane</name><salary>60000</salary></row><row><name>Bob</name></row><row><name>Alice</name><salary>70000</salary></row><row/>
 ~~END~~
 
 
@@ -950,7 +950,7 @@ SELECT CAST(NULL AS VARCHAR(10)) AS null_val FOR XML RAW, ELEMENTS;
 GO
 ~~START~~
 ntext
-<row></row>
+<row/>
 ~~END~~
 
 
@@ -971,10 +971,20 @@ SELECT 1 AS a, 2 AS b FOR XML RAW(''), ELEMENTS;
 GO
 ~~START~~
 ntext
-<><a>1</a><b>2</b></>
+<a>1</a><b>2</b>
 ~~END~~
 
 
+-- Empty element name without ELEMENTS (attribute-centric) - should error
+SELECT 1 AS a, 2 AS b FOR XML RAW('');
+GO
+~~START~~
+ntext
+~~ERROR (Code: 33557097)~~
+
+~~ERROR (Message: Row tag omission (empty row tag name) cannot be used with attribute-centric FOR XML serialization.)~~
+
+
 -- Element name with spaces
 SELECT 1 AS a FOR XML RAW('element name'), ELEMENTS;
 GO

test/JDBC/input/forxml/forxml-raw-elements-vu-verify.sql

@@ -414,6 +414,10 @@ GO
 SELECT 1 AS a, 2 AS b FOR XML RAW(''), ELEMENTS;
 GO
 
+-- Empty element name without ELEMENTS (attribute-centric) - should error
+SELECT 1 AS a, 2 AS b FOR XML RAW('');
+GO
+
 -- Element name with spaces
 SELECT 1 AS a FOR XML RAW('element name'), ELEMENTS;
 GO