Add XMLText function (SQL/XML X038)

This function implements the standard XMLTest function, which
converts text into xml text nodes. It uses the libxml2 function
xmlEncodeSpecialChars to escape predefined entities (&"<>), so
that those do not cause any conflict when concatenating the text
node output with existing xml documents.

This also adds a note in  features.sgml about not supporting
XML(SEQUENCE). The SQL specification defines a RETURNING clause
to a set of XML functions, where RETURNING CONTENT or RETURNING
SEQUENCE can be defined. Since PostgreSQL doesn't support
XML(SEQUENCE) all of these functions operate with an
implicit RETURNING CONTENT.

Author: Jim Jones 
Reviewed-by: Vik Fearing 
Discussion: https://postgr.es/m/86617a66-ec95-581f-8d54-08059cca8885@uni-muenster.de

diff --git a/doc/src/sgml/features.sgml b/doc/src/sgml/features.sgml
index 575afa34760c713081a9ea8768ef09a5864ce32e..966fd39882760786f1dc5f60df2de0d88663d854 100644 (file)
--- a/doc/src/sgml/features.sgml
+++ b/doc/src/sgml/features.sgml
@@ -199,6 +199,15 @@
        standard.
       
      
+
+     
+      
+       PostgreSQL does not support the
+       RETURNING CONTENT or RETURNING SEQUENCE
+       clauses, functions which are defined to have these in the specification
+       are implicitly returning content.
+      
+     
     
    
 

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index a6fcac0824add8e13ab22c9dcabb15e2a1f26fac..d963f0a0a0000160e11ee75b22afd1affdd19046 100644 (file)
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -14180,6 +14180,36 @@ CREATE TYPE rainbow AS ENUM ('red', 'orange', 'yellow', 'green', 'blue', 'purple
     documents for processing in client applications.
    
 
+  
+    <literal>xmltext</literal>
+
+    
+     xmltext
+    
+
+
+xmltext ( text ) xml
+
+
+    
+     The function xmltext returns an XML value with a single
+     text node containing the input argument as its content. Predefined entities
+     like ampersand (), left and right angle brackets
+     (]]>), and quotation marks ()
+     are escaped.
+    
+
+    
+     Example:
+
+SELECT xmltext('< foo & bar >');
+         xmltext
+-------------------------
+ < foo & bar >
+]]>
+    
+   
+
    
     <literal>xmlcomment</literal>
 


diff --git a/src/backend/catalog/sql_features.txt b/src/backend/catalog/sql_features.txt

index b33065d7bf7c8034f3f3bb2b46c0ea8786392f0b..80c40eaf5780142bef83cc0f6bc03754cf5965c2 100644 (file)

--- a/src/backend/catalog/sql_features.txt
+++ b/src/backend/catalog/sql_features.txt
@@ -633,7 +633,7 @@ X034    XMLAgg          YES
 X035   XMLAgg: ORDER BY option         YES 
 X036   XMLComment          YES 
 X037   XMLPI           YES 
-X038   XMLText         NO  
+X038   XMLText         YES supported except for RETURNING
 X040   Basic table mapping         YES 
 X041   Basic table mapping: null absent            YES 
 X042   Basic table mapping: null as nil            YES 


diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c

index 2300c7ebf340c0034da17a26e1018404fabc3f49..c401e7b821986a9697efcda5be7f5ae8448a2a30 100644 (file)

--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -47,6 +47,7 @@
 
 #ifdef USE_LIBXML
 #include 
+#include 
 #include 
 #include 
 #include 
@@ -513,6 +514,27 @@ xmlcomment(PG_FUNCTION_ARGS)
 }
 
 
+Datum
+xmltext(PG_FUNCTION_ARGS)
+{
+#ifdef USE_LIBXML
+   text       *arg = PG_GETARG_TEXT_PP(0);
+   text       *result;
+   xmlChar    *xmlbuf = NULL;
+
+   xmlbuf = xmlEncodeSpecialChars(NULL, xml_text2xmlChar(arg));
+
+   Assert(xmlbuf);
+
+   result = cstring_to_text_with_len((const char *) xmlbuf, xmlStrlen(xmlbuf));
+   xmlFree(xmlbuf);
+   PG_RETURN_XML_P(result);
+#else
+   NO_XML_SUPPORT();
+   return 0;
+#endif                         /* not USE_LIBXML */
+}
+
 
 /*
  * TODO: xmlconcat needs to merge the notations and unparsed entities


diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat

index 091f7e343c3da673036ea7fbd57304e1dadbfe39..f14aed422a765f3c3b6dff82f610c2964855630e 100644 (file)

--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -8793,6 +8793,9 @@
 { oid => '2922', descr => 'serialize an XML value to a character string',
   proname => 'text', prorettype => 'text', proargtypes => 'xml',
   prosrc => 'xmltotext' },
+{ oid => '3813', descr => 'generate XML text node',
+  proname => 'xmltext', proisstrict => 't', prorettype => 'xml',
+  proargtypes => 'text', prosrc => 'xmltext' },
 
 { oid => '2923', descr => 'map table contents to XML',
   proname => 'table_to_xml', procost => '100', provolatile => 's',


diff --git a/src/test/regress/expected/xml.out b/src/test/regress/expected/xml.out

index 398345ca67fe69939fec69b6ee6650fd708818a8..13e4296bf8ffbe1225824adcc06ac559b8443b2b 100644 (file)

--- a/src/test/regress/expected/xml.out
+++ b/src/test/regress/expected/xml.out
@@ -1785,3 +1785,39 @@ SELECT * FROM XMLTABLE('.' PASSING XMLELEMENT(NAME a) columns a varchar(20) PATH
   | <foo/>
 (1 row)
 
+SELECT xmltext(NULL);
+ xmltext 
+---------
+ 
+(1 row)
+
+SELECT xmltext('');
+ xmltext 
+---------
+ 
+(1 row)
+
+SELECT xmltext('  ');
+ xmltext 
+---------
+   
+(1 row)
+
+SELECT xmltext('foo `$_-+?=*^%!|/\()[]{}');
+         xmltext          
+--------------------------
+ foo `$_-+?=*^%!|/\()[]{}
+(1 row)
+
+SELECT xmltext('foo & <"bar">');
+              xmltext              
+-----------------------------------
+ foo & <"bar">
+(1 row)
+
+SELECT xmltext('x'|| '73'::xml || .42 || true || 'j'::char);
+             xmltext             
+---------------------------------
+ x<P>73</P>0.42truej
+(1 row)
+


diff --git a/src/test/regress/expected/xml_1.out b/src/test/regress/expected/xml_1.out

index 63b779470ff6dcd09f4f4ac3b0b68da0ee622784..eb9c6f2ed4196ceea64f80e80b5853679e9245a2 100644 (file)

--- a/src/test/regress/expected/xml_1.out
+++ b/src/test/regress/expected/xml_1.out
@@ -1402,3 +1402,26 @@ DETAIL:  This functionality requires the server to be built with libxml support.
 SELECT * FROM XMLTABLE('.' PASSING XMLELEMENT(NAME a) columns a varchar(20) PATH '""', b xml PATH '""');
 ERROR:  unsupported XML feature
 DETAIL:  This functionality requires the server to be built with libxml support.
+SELECT xmltext(NULL);
+ xmltext 
+---------
+ 
+(1 row)
+
+SELECT xmltext('');
+ERROR:  unsupported XML feature
+DETAIL:  This functionality requires the server to be built with libxml support.
+SELECT xmltext('  ');
+ERROR:  unsupported XML feature
+DETAIL:  This functionality requires the server to be built with libxml support.
+SELECT xmltext('foo `$_-+?=*^%!|/\()[]{}');
+ERROR:  unsupported XML feature
+DETAIL:  This functionality requires the server to be built with libxml support.
+SELECT xmltext('foo & <"bar">');
+ERROR:  unsupported XML feature
+DETAIL:  This functionality requires the server to be built with libxml support.
+SELECT xmltext('x'|| '73'::xml || .42 || true || 'j'::char);
+ERROR:  unsupported XML feature
+LINE 1: SELECT xmltext('x'|| '73'::xml || .42 || true || 'j':...
+                             ^
+DETAIL:  This functionality requires the server to be built with libxml support.


diff --git a/src/test/regress/expected/xml_2.out b/src/test/regress/expected/xml_2.out

index 43c2558352a3a21bb7c0a32a4508291507fbd3ca..c8ed8e0cfa60f525629c769c44d2c4e51c716097 100644 (file)

--- a/src/test/regress/expected/xml_2.out
+++ b/src/test/regress/expected/xml_2.out
@@ -1765,3 +1765,39 @@ SELECT * FROM XMLTABLE('.' PASSING XMLELEMENT(NAME a) columns a varchar(20) PATH
   | <foo/>
 (1 row)
 
+SELECT xmltext(NULL);
+ xmltext 
+---------
+ 
+(1 row)
+
+SELECT xmltext('');
+ xmltext 
+---------
+ 
+(1 row)
+
+SELECT xmltext('  ');
+ xmltext 
+---------
+   
+(1 row)
+
+SELECT xmltext('foo `$_-+?=*^%!|/\()[]{}');
+         xmltext          
+--------------------------
+ foo `$_-+?=*^%!|/\()[]{}
+(1 row)
+
+SELECT xmltext('foo & <"bar">');
+              xmltext              
+-----------------------------------
+ foo & <"bar">
+(1 row)
+
+SELECT xmltext('x'|| '73'::xml || .42 || true || 'j'::char);
+             xmltext             
+---------------------------------
+ x<P>73</P>0.42truej
+(1 row)
+


diff --git a/src/test/regress/sql/xml.sql b/src/test/regress/sql/xml.sql

index a591eea2e5d14dec4acf4501d59ddfd8d6d70b25..bd4a4e7acdf8f4d5598a1525bb82d9e113ca01b0 100644 (file)

--- a/src/test/regress/sql/xml.sql
+++ b/src/test/regress/sql/xml.sql
@@ -660,3 +660,10 @@ SELECT * FROM XMLTABLE('*' PASSING 'pre
 \x
 
 SELECT * FROM XMLTABLE('.' PASSING XMLELEMENT(NAME a) columns a varchar(20) PATH '""', b xml PATH '""');
+
+SELECT xmltext(NULL);
+SELECT xmltext('');
+SELECT xmltext('  ');
+SELECT xmltext('foo `$_-+?=*^%!|/\()[]{}');
+SELECT xmltext('foo & <"bar">');
+SELECT xmltext('x'|| '73'::xml || .42 || true || 'j'::char);
\ No newline at end of file

diff --git a/src/backend/catalog/sql_features.txt b/src/backend/catalog/sql_features.txt
index b33065d7bf7c8034f3f3bb2b46c0ea8786392f0b..80c40eaf5780142bef83cc0f6bc03754cf5965c2 100644 (file)
--- a/src/backend/catalog/sql_features.txt
+++ b/src/backend/catalog/sql_features.txt
@@ -633,7 +633,7 @@ X034    XMLAgg          YES
 X035   XMLAgg: ORDER BY option         YES 
 X036   XMLComment          YES 
 X037   XMLPI           YES 
-X038   XMLText         NO  
+X038   XMLText         YES supported except for RETURNING
 X040   Basic table mapping         YES 
 X041   Basic table mapping: null absent            YES 
 X042   Basic table mapping: null as nil            YES 

diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
index 2300c7ebf340c0034da17a26e1018404fabc3f49..c401e7b821986a9697efcda5be7f5ae8448a2a30 100644 (file)
--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -47,6 +47,7 @@
 
 #ifdef USE_LIBXML
 #include 
+#include 
 #include 
 #include 
 #include 
@@ -513,6 +514,27 @@ xmlcomment(PG_FUNCTION_ARGS)
 }
 
 
+Datum
+xmltext(PG_FUNCTION_ARGS)
+{
+#ifdef USE_LIBXML
+   text       *arg = PG_GETARG_TEXT_PP(0);
+   text       *result;
+   xmlChar    *xmlbuf = NULL;
+
+   xmlbuf = xmlEncodeSpecialChars(NULL, xml_text2xmlChar(arg));
+
+   Assert(xmlbuf);
+
+   result = cstring_to_text_with_len((const char *) xmlbuf, xmlStrlen(xmlbuf));
+   xmlFree(xmlbuf);
+   PG_RETURN_XML_P(result);
+#else
+   NO_XML_SUPPORT();
+   return 0;
+#endif                         /* not USE_LIBXML */
+}
+
 
 /*
  * TODO: xmlconcat needs to merge the notations and unparsed entities

diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 091f7e343c3da673036ea7fbd57304e1dadbfe39..f14aed422a765f3c3b6dff82f610c2964855630e 100644 (file)
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -8793,6 +8793,9 @@
 { oid => '2922', descr => 'serialize an XML value to a character string',
   proname => 'text', prorettype => 'text', proargtypes => 'xml',
   prosrc => 'xmltotext' },
+{ oid => '3813', descr => 'generate XML text node',
+  proname => 'xmltext', proisstrict => 't', prorettype => 'xml',
+  proargtypes => 'text', prosrc => 'xmltext' },
 
 { oid => '2923', descr => 'map table contents to XML',
   proname => 'table_to_xml', procost => '100', provolatile => 's',

diff --git a/src/test/regress/expected/xml.out b/src/test/regress/expected/xml.out
index 398345ca67fe69939fec69b6ee6650fd708818a8..13e4296bf8ffbe1225824adcc06ac559b8443b2b 100644 (file)
--- a/src/test/regress/expected/xml.out
+++ b/src/test/regress/expected/xml.out
@@ -1785,3 +1785,39 @@ SELECT * FROM XMLTABLE('.' PASSING XMLELEMENT(NAME a) columns a varchar(20) PATH
   | <foo/>
 (1 row)
 
+SELECT xmltext(NULL);
+ xmltext 
+---------
+ 
+(1 row)
+
+SELECT xmltext('');
+ xmltext 
+---------
+ 
+(1 row)
+
+SELECT xmltext('  ');
+ xmltext 
+---------
+   
+(1 row)
+
+SELECT xmltext('foo `$_-+?=*^%!|/\()[]{}');
+         xmltext          
+--------------------------
+ foo `$_-+?=*^%!|/\()[]{}
+(1 row)
+
+SELECT xmltext('foo & <"bar">');
+              xmltext              
+-----------------------------------
+ foo & <"bar">
+(1 row)
+
+SELECT xmltext('x'|| '73'::xml || .42 || true || 'j'::char);
+             xmltext             
+---------------------------------
+ x<P>73</P>0.42truej
+(1 row)
+

diff --git a/src/test/regress/expected/xml_1.out b/src/test/regress/expected/xml_1.out
index 63b779470ff6dcd09f4f4ac3b0b68da0ee622784..eb9c6f2ed4196ceea64f80e80b5853679e9245a2 100644 (file)
--- a/src/test/regress/expected/xml_1.out
+++ b/src/test/regress/expected/xml_1.out
@@ -1402,3 +1402,26 @@ DETAIL:  This functionality requires the server to be built with libxml support.
 SELECT * FROM XMLTABLE('.' PASSING XMLELEMENT(NAME a) columns a varchar(20) PATH '""', b xml PATH '""');
 ERROR:  unsupported XML feature
 DETAIL:  This functionality requires the server to be built with libxml support.
+SELECT xmltext(NULL);
+ xmltext 
+---------
+ 
+(1 row)
+
+SELECT xmltext('');
+ERROR:  unsupported XML feature
+DETAIL:  This functionality requires the server to be built with libxml support.
+SELECT xmltext('  ');
+ERROR:  unsupported XML feature
+DETAIL:  This functionality requires the server to be built with libxml support.
+SELECT xmltext('foo `$_-+?=*^%!|/\()[]{}');
+ERROR:  unsupported XML feature
+DETAIL:  This functionality requires the server to be built with libxml support.
+SELECT xmltext('foo & <"bar">');
+ERROR:  unsupported XML feature
+DETAIL:  This functionality requires the server to be built with libxml support.
+SELECT xmltext('x'|| '73'::xml || .42 || true || 'j'::char);
+ERROR:  unsupported XML feature
+LINE 1: SELECT xmltext('x'|| '73'::xml || .42 || true || 'j':...
+                             ^
+DETAIL:  This functionality requires the server to be built with libxml support.

diff --git a/src/test/regress/expected/xml_2.out b/src/test/regress/expected/xml_2.out
index 43c2558352a3a21bb7c0a32a4508291507fbd3ca..c8ed8e0cfa60f525629c769c44d2c4e51c716097 100644 (file)
--- a/src/test/regress/expected/xml_2.out
+++ b/src/test/regress/expected/xml_2.out
@@ -1765,3 +1765,39 @@ SELECT * FROM XMLTABLE('.' PASSING XMLELEMENT(NAME a) columns a varchar(20) PATH
   | <foo/>
 (1 row)
 
+SELECT xmltext(NULL);
+ xmltext 
+---------
+ 
+(1 row)
+
+SELECT xmltext('');
+ xmltext 
+---------
+ 
+(1 row)
+
+SELECT xmltext('  ');
+ xmltext 
+---------
+   
+(1 row)
+
+SELECT xmltext('foo `$_-+?=*^%!|/\()[]{}');
+         xmltext          
+--------------------------
+ foo `$_-+?=*^%!|/\()[]{}
+(1 row)
+
+SELECT xmltext('foo & <"bar">');
+              xmltext              
+-----------------------------------
+ foo & <"bar">
+(1 row)
+
+SELECT xmltext('x'|| '73'::xml || .42 || true || 'j'::char);
+             xmltext             
+---------------------------------
+ x<P>73</P>0.42truej
+(1 row)
+

diff --git a/src/test/regress/sql/xml.sql b/src/test/regress/sql/xml.sql
index a591eea2e5d14dec4acf4501d59ddfd8d6d70b25..bd4a4e7acdf8f4d5598a1525bb82d9e113ca01b0 100644 (file)
--- a/src/test/regress/sql/xml.sql
+++ b/src/test/regress/sql/xml.sql
@@ -660,3 +660,10 @@ SELECT * FROM XMLTABLE('*' PASSING 'pre
 \x
 
 SELECT * FROM XMLTABLE('.' PASSING XMLELEMENT(NAME a) columns a varchar(20) PATH '""', b xml PATH '""');
+
+SELECT xmltext(NULL);
+SELECT xmltext('');
+SELECT xmltext('  ');
+SELECT xmltext('foo `$_-+?=*^%!|/\()[]{}');
+SELECT xmltext('foo & <"bar">');
+SELECT xmltext('x'|| '73'::xml || .42 || true || 'j'::char);
\ No newline at end of file