open-dsi
/
postgres
mirror of https://github.com/postgres/postgres
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Add xmlpath() to evaluate XPath expressions, with namespaces support.

Browse Source 
Nikolay Samokhvalov
REL8_3_STABLE
Bruce Momjian 19 years ago
parent 4f896dac17
commit e651bcf3f6
6 changed files with 309 additions and 4 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Show Stats Download Patch File Download Diff File
  1. 251
      src/backend/utils/adt/xml.c
  2. 6
      src/include/catalog/pg_proc.h
  3. 3
      src/include/utils/xml.h
  4. 30
      src/test/regress/expected/xml.out
  5. 15
      src/test/regress/expected/xml_1.out
  6. 8
      src/test/regress/sql/xml.sql

251
src/backend/utils/adt/xml.c
Unescape View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/backend/utils/adt/xml.c,v 1.35 2007/03/15 23:12:06 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/xml.c,v 1.36 2007/03/22 20:14:58 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -47,6 +47,8 @@
#include <libxml/uri.h>
#include <libxml/xmlerror.h>
#include <libxml/xmlwriter.h>
#include <libxml/xpath.h>
#include <libxml/xpathInternals.h>
#endif /* USE_LIBXML */
#include "catalog/namespace.h"
@ -67,6 +69,7 @@
#include "utils/datetime.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "access/tupmacs.h"
#include "utils/xml.h"
@ -88,6 +91,7 @@ static xmlChar *xml_text2xmlChar(text *in);
static int parse_xml_decl(const xmlChar *str, size_t *lenp, xmlChar **version, xmlChar **encoding, int *standalone);
static bool print_xml_decl(StringInfo buf, const xmlChar *version, pg_enc encoding, int standalone);
static xmlDocPtr xml_parse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace, xmlChar *encoding);
static text *xml_xmlnodetotext(xmlNodePtr cur);
#endif /* USE_LIBXML */
@ -1463,7 +1467,6 @@ map_xml_name_to_sql_identifier(char *name)
return buf.data;
}
/*
* Map SQL value to XML value; see SQL/XML:2003 section 9.16.
*/
@ -2403,3 +2406,247 @@ SPI_sql_row_to_xmlelement(int rownum, StringInfo result, char *tablename, bool n
else
appendStringInfoString(result, "</row>\n\n");
}
/*
* XPath related functions
*/
#ifdef USE_LIBXML
/*
* Convert XML node to text (return value only, it's not dumping)
*/
text *
xml_xmlnodetotext(xmlNodePtr cur)
{
xmlChar *str;
text *result;
size_t len;
str = xmlXPathCastNodeToString(cur);
len = strlen((char *) str);
result = (text *) palloc(len + VARHDRSZ);
SET_VARSIZE(result, len + VARHDRSZ);
memcpy(VARDATA(result), str, len);
return result;
}
#endif
/*
* Evaluate XPath expression and return array of XML values.
* As we have no support of XQuery sequences yet, this functions seems
* to be the most useful one (array of XML functions plays a role of
* some kind of substritution for XQuery sequences).
* Workaround here: we parse XML data in different way to allow XPath for
* fragments (see "XPath for fragment" TODO comment inside).
*/
Datum
xmlpath(PG_FUNCTION_ARGS)
{
#ifdef USE_LIBXML
ArrayBuildState *astate = NULL;
xmlParserCtxtPtr ctxt = NULL;
xmlDocPtr doc = NULL;
xmlXPathContextPtr xpathctx = NULL;
xmlXPathCompExprPtr xpathcomp = NULL;
xmlXPathObjectPtr xpathobj = NULL;
int32 len, xpath_len;
xmlChar *string, *xpath_expr;
bool res_is_null = FALSE;
int i;
xmltype *data;
text *xpath_expr_text;
ArrayType *namespaces;
int *dims, ndims, ns_count = 0, bitmask = 1;
char *ptr;
bits8 *bitmap;
char **ns_names = NULL, **ns_uris = NULL;
int16 typlen;
bool typbyval;
char typalign;
/* the function is not strict, we must check first two args */
if (PG_ARGISNULL(0) || PG_ARGISNULL(1))
PG_RETURN_NULL();
xpath_expr_text = PG_GETARG_TEXT_P(0);
data = PG_GETARG_XML_P(1);
/* Namespace mappings passed as text[].
* Assume that 2-dimensional array has been passed,
* the 1st subarray is array of names, the 2nd -- array of URIs,
* example: ARRAY[ARRAY['myns', 'myns2'], ARRAY['http://example.com', 'http://example2.com']].
*/
if (!PG_ARGISNULL(2))
{
namespaces = PG_GETARG_ARRAYTYPE_P(2);
ndims = ARR_NDIM(namespaces);
dims = ARR_DIMS(namespaces);
/* Sanity check */
if (ndims != 2)
ereport(ERROR, (errmsg("invalid array passed for namespace mappings"),
errdetail("Only 2-dimensional array may be used for namespace mappings.")));
Assert(ARR_ELEMTYPE(namespaces) == TEXTOID);
ns_count = ArrayGetNItems(ndims, dims) / 2;
get_typlenbyvalalign(ARR_ELEMTYPE(namespaces),
&typlen, &typbyval, &typalign);
ns_names = (char **) palloc(ns_count * sizeof(char *));
ns_uris = (char **) palloc(ns_count * sizeof(char *));
ptr = ARR_DATA_PTR(namespaces);
bitmap = ARR_NULLBITMAP(namespaces);
bitmask = 1;
for (i = 0; i < ns_count * 2; i++)
{
if (bitmap && (*bitmap & bitmask) == 0)
ereport(ERROR, (errmsg("neither namespace nor URI may be NULL"))); /* TODO: better message */
else
{
if (i < ns_count)
ns_names[i] = DatumGetCString(DirectFunctionCall1(textout,
PointerGetDatum(ptr)));
else
ns_uris[i - ns_count] = DatumGetCString(DirectFunctionCall1(textout,
PointerGetDatum(ptr)));
ptr = att_addlength(ptr, typlen, PointerGetDatum(ptr));
ptr = (char *) att_align(ptr, typalign);
}
/* advance bitmap pointer if any */
if (bitmap)
{
bitmask <<= 1;
if (bitmask == 0x100)
{
bitmap++;
bitmask = 1;
}
}
}
}
len = VARSIZE(data) - VARHDRSZ;
xpath_len = VARSIZE(xpath_expr_text) - VARHDRSZ;
if (xpath_len == 0)
ereport(ERROR, (errmsg("empty XPath expression")));
if (xmlStrncmp((xmlChar *) VARDATA(data), (xmlChar *) "<?xml", 5) == 0)
{
string = palloc(len + 1);
memcpy(string, VARDATA(data), len);
string[len] = '\0';
xpath_expr = palloc(xpath_len + 1);
memcpy(xpath_expr, VARDATA(xpath_expr_text), xpath_len);
xpath_expr[xpath_len] = '\0';
}
else
{
/* use "<x>...</x>" as dummy root element to enable XPath for fragments */
/* TODO: (XPath for fragment) find better solution to work with XML fragment! */
string = xmlStrncatNew((xmlChar *) "<x>", (xmlChar *) VARDATA(data), len);
string = xmlStrncat(string, (xmlChar *) "</x>", 5);
len += 7;
xpath_expr = xmlStrncatNew((xmlChar *) "/x", (xmlChar *) VARDATA(xpath_expr_text), xpath_len);
len += 2;
}
xml_init();
PG_TRY();
{
/* redundant XML parsing (two parsings for the same value in the same session are possible) */
ctxt = xmlNewParserCtxt();
if (ctxt == NULL)
xml_ereport(ERROR, ERRCODE_INTERNAL_ERROR,
"could not allocate parser context");
doc = xmlCtxtReadMemory(ctxt, (char *) string, len, NULL, NULL, 0);
if (doc == NULL)
xml_ereport(ERROR, ERRCODE_INVALID_XML_DOCUMENT,
"could not parse XML data");
xpathctx = xmlXPathNewContext(doc);
if (xpathctx == NULL)
xml_ereport(ERROR, ERRCODE_INTERNAL_ERROR,
"could not allocate XPath context");
xpathctx->node = xmlDocGetRootElement(doc);
if (xpathctx->node == NULL)
xml_ereport(ERROR, ERRCODE_INTERNAL_ERROR,
"could not find root XML element");
/* register namespaces, if any */
if ((ns_count > 0) && ns_names && ns_uris)
for (i = 0; i < ns_count; i++)
if (0 != xmlXPathRegisterNs(xpathctx, (xmlChar *) ns_names[i], (xmlChar *) ns_uris[i]))
ereport(ERROR,
(errmsg("could not register XML namespace with prefix=\"%s\" and href=\"%s\"", ns_names[i], ns_uris[i])));
xpathcomp = xmlXPathCompile(xpath_expr);
if (xpathcomp == NULL)
xml_ereport(ERROR, ERRCODE_INTERNAL_ERROR,
"invalid XPath expression"); /* TODO: show proper XPath error details */
xpathobj = xmlXPathCompiledEval(xpathcomp, xpathctx);
xmlXPathFreeCompExpr(xpathcomp);
if (xpathobj == NULL)
ereport(ERROR, (errmsg("could not create XPath object")));
if (xpathobj->nodesetval == NULL)
res_is_null = TRUE;
if (!res_is_null && xpathobj->nodesetval->nodeNr == 0)
/* TODO maybe empty array should be here, not NULL? (if so -- fix segfault) */
/*PG_RETURN_ARRAYTYPE_P(makeArrayResult(astate, CurrentMemoryContext));*/
res_is_null = TRUE;
if (!res_is_null)
for (i = 0; i < xpathobj->nodesetval->nodeNr; i++)
{
Datum elem;
bool elemisnull = false;
elem = PointerGetDatum(xml_xmlnodetotext(xpathobj->nodesetval->nodeTab[i]));
astate = accumArrayResult(astate, elem,
elemisnull, XMLOID,
CurrentMemoryContext);
}
xmlXPathFreeObject(xpathobj);
xmlXPathFreeContext(xpathctx);
xmlFreeParserCtxt(ctxt);
xmlFreeDoc(doc);
xmlCleanupParser();
}
PG_CATCH();
{
if (xpathcomp)
xmlXPathFreeCompExpr(xpathcomp);
if (xpathobj)
xmlXPathFreeObject(xpathobj);
if (xpathctx)
xmlXPathFreeContext(xpathctx);
if (doc)
xmlFreeDoc(doc);
if (ctxt)
xmlFreeParserCtxt(ctxt);
xmlCleanupParser();
PG_RE_THROW();
}
PG_END_TRY();
if (res_is_null)
{
PG_RETURN_NULL();
}
else
{
PG_RETURN_ARRAYTYPE_P(makeArrayResult(astate, CurrentMemoryContext));
}
#else
NO_XML_SUPPORT();
return 0;
#endif
}

6
src/include/catalog/pg_proc.h
Unescape View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.449 2007/03/20 05:45:00 neilc Exp $
* $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.450 2007/03/22 20:14:58 momjian Exp $
*
* NOTES
* The script catalog/genbki.sh reads this file and generates .bki
@ -4095,6 +4095,10 @@ DESCR("map table contents and structure to XML and XML Schema");
DATA(insert OID = 2930 ( query_to_xml_and_xmlschema PGNSP PGUID 12 100 0 f f t f s 4 142 "25 16 16 25" _null_ _null_ "{query,nulls,tableforest,targetns}" query_to_xml_and_xmlschema - _null_ ));
DESCR("map query result and structure to XML and XML Schema");
DATA(insert OID = 2931 ( xmlpath PGNSP PGUID 12 1 0 f f f f i 3 143 "25 142 1009" _null_ _null_ _null_ xmlpath - _null_ ));
DESCR("evaluate XPath expression, with namespaces support");
DATA(insert OID = 2932 ( xmlpath PGNSP PGUID 14 1 0 f f f f i 2 143 "25 142" _null_ _null_ _null_ "select pg_catalog.xmlpath($1, $2, NULL)" - _null_ ));
DESCR("evaluate XPath expression");
/* uuid */
DATA(insert OID = 2952 ( uuid_in PGNSP PGUID 12 1 0 f f t f i 1 2950 "2275" _null_ _null_ _null_ uuid_in - _null_ ));

3
src/include/utils/xml.h
Unescape View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/utils/xml.h,v 1.16 2007/02/16 07:46:55 petere Exp $
* $PostgreSQL: pgsql/src/include/utils/xml.h,v 1.17 2007/03/22 20:14:58 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -36,6 +36,7 @@ extern Datum xmlconcat2(PG_FUNCTION_ARGS);
extern Datum texttoxml(PG_FUNCTION_ARGS);
extern Datum xmltotext(PG_FUNCTION_ARGS);
extern Datum xmlvalidate(PG_FUNCTION_ARGS);
extern Datum xmlpath(PG_FUNCTION_ARGS);
extern Datum table_to_xml(PG_FUNCTION_ARGS);
extern Datum query_to_xml(PG_FUNCTION_ARGS);

30
src/test/regress/expected/xml.out
Unescape View File

@ -401,3 +401,33 @@ SELECT table_name, view_definition FROM information_schema.views
xmlview9 | SELECT XMLSERIALIZE(CONTENT 'good'::"xml" AS text) AS "xmlserialize";
(9 rows)
-- Text XPath expressions evaluation
SELECT xmlpath('/value', data) FROM xmltest;
xmlpath
---------
{one}
{two}
(2 rows)
SELECT xmlpath(NULL, NULL) IS NULL FROM xmltest;
?column?
----------
t
t
(2 rows)
SELECT xmlpath('', '<!-- error -->');
ERROR: empty XPath expression
CONTEXT: SQL function "xmlpath" statement 1
SELECT xmlpath('//text()', '<local:data xmlns:local="http://127.0.0.1"><local:piece id="1">number one</local:piece><local:piece id="2" /></local:data>');
xmlpath
----------------
{"number one"}
(1 row)
SELECT xmlpath('//loc:piece/@id', '<local:data xmlns:local="http://127.0.0.1"><local:piece id="1">number one</local:piece><local:piece id="2" /></local:data>', ARRAY[ARRAY['loc'], ARRAY['http://127.0.0.1']]);
xmlpath
---------
{1,2}
(1 row)

15
src/test/regress/expected/xml_1.out
Unescape View File

@ -197,3 +197,18 @@ SELECT table_name, view_definition FROM information_schema.views
xmlview5 | SELECT XMLPARSE(CONTENT '<abc>x</abc>'::text STRIP WHITESPACE) AS "xmlparse";
(2 rows)
-- Text XPath expressions evaluation
SELECT xmlpath('/value', data) FROM xmltest;
xmlpath
---------
(0 rows)
SELECT xmlpath(NULL, NULL) IS NULL FROM xmltest;
ERROR: no XML support in this installation
CONTEXT: SQL function "xmlpath" statement 1
SELECT xmlpath('', '<!-- error -->');
ERROR: no XML support in this installation
SELECT xmlpath('//text()', '<local:data xmlns:local="http://127.0.0.1"><local:piece id="1">number one</local:piece><local:piece id="2" /></local:data>');
ERROR: no XML support in this installation
SELECT xmlpath('//loc:piece/@id', '<local:data xmlns:local="http://127.0.0.1"><local:piece id="1">number one</local:piece><local:piece id="2" /></local:data>', ARRAY[ARRAY['loc'], ARRAY['http://127.0.0.1']]);
ERROR: no XML support in this installation

8
src/test/regress/sql/xml.sql
Unescape View File

@ -144,3 +144,11 @@ CREATE VIEW xmlview9 AS SELECT xmlserialize(content 'good' as text);
SELECT table_name, view_definition FROM information_schema.views
WHERE table_name LIKE 'xmlview%' ORDER BY 1;
-- Text XPath expressions evaluation
SELECT xmlpath('/value', data) FROM xmltest;
SELECT xmlpath(NULL, NULL) IS NULL FROM xmltest;
SELECT xmlpath('', '<!-- error -->');
SELECT xmlpath('//text()', '<local:data xmlns:local="http://127.0.0.1"><local:piece id="1">number one</local:piece><local:piece id="2" /></local:data>');
SELECT xmlpath('//loc:piece/@id', '<local:data xmlns:local="http://127.0.0.1"><local:piece id="1">number one</local:piece><local:piece id="2" /></local:data>', ARRAY[ARRAY['loc'], ARRAY['http://127.0.0.1']]);

Write Preview
Loading…
Cancel
Save