On 06/08/10 20:55, Peter Eisentraut wrote:
On fre, 2010-08-06 at 09:04 +0100, Mike Fowler wrote:
If the patch is to be committed, does it make sense for me to refine
it such that it uses the new xpath internal function you extracted in
the xmlexists patch?
Yes, you can probably shrink this patch down to about 20 lines.
Updated the patch so that it will apply to head and re-worked the
function to use the new xpath internal function.
Regards,
--
Mike Fowler
Registered Linux user: 379787
*** a/doc/src/sgml/func.sgml
--- b/doc/src/sgml/func.sgml
***************
*** 8693,8698 **** SELECT xpath('//mydefns:b/text()', '<a xmlns="http://example.com";><b>test</b></a
--- 8693,8731 ----
(1 row)
]]></screen>
</para>
+
+ <sect3>
+ <title>xpath_exists</title>
+
+ <indexterm>
+ <primary>xpath_exists</primary>
+ </indexterm>
+
+ <synopsis>
+ <function>xpath_exists</function>(<replaceable>xpath</replaceable>, <replaceable>xml</replaceable><optional>, <replaceable>nsarray</replaceable></optional>)
+ </synopsis>
+
+ <para>
+ The function <function>xpath_exists</function> is a specialised form
+ of the <function>xpath</function> function. Though the functions are
+ syntactically the same the xpath expressions are evaluated in differing
+ contexts. Instead of returning the XML values that satisfy the xpath, this
+ function returns a boolean indicating whether the query was satisfied or not.
+ </para>
+
+ <para>
+ Example:
+ <screen><![CDATA[
+ SELECT xpath_exists('/my:a/text()', '<my:a xmlns:my="http://example.com";>test</my:a>',
+ ARRAY[ARRAY['my', 'http://example.com']]);
+
+ xpath_exists
+ ------------
+ t
+ (1 row)
+ ]]></screen>
+ </para>
+ </sect3>
</sect2>
<sect2 id="functions-xml-mapping">
*** a/src/backend/utils/adt/xml.c
--- b/src/backend/utils/adt/xml.c
***************
*** 3541,3543 **** Datum xmlexists(PG_FUNCTION_ARGS)
--- 3541,3567 ----
return 0;
#endif
}
+
+ /*
+ * Determines if the node specified by the supplied XPath exists
+ * in a given XML document, returning a boolean. Differs from
+ * xmlexists as it supports namespaces and is not defined in SQL/XML.
+ */
+ Datum
+ xpath_exists(PG_FUNCTION_ARGS)
+ {
+ #ifdef USE_LIBXML
+ text *xpath_expr_text = PG_GETARG_TEXT_P(0);
+ xmltype *data = PG_GETARG_XML_P(1);
+ ArrayType *namespaces = PG_GETARG_ARRAYTYPE_P(2);
+ int res_nitems;
+
+ xpath_internal(xpath_expr_text, data, namespaces,
+ &res_nitems, NULL);
+
+ PG_RETURN_BOOL(res_nitems > 0);
+ #else
+ NO_XML_SUPPORT();
+ return 0;
+ #endif
+ }
*** a/src/include/catalog/pg_proc.h
--- b/src/include/catalog/pg_proc.h
***************
*** 4390,4395 **** DESCR("evaluate XPath expression");
--- 4390,4400 ----
DATA(insert OID = 2614 ( xmlexists PGNSP PGUID 12 1 0 0 f f f t f i 2 0 16 "25 142" _null_ _null_ _null_ _null_ xmlexists _null_ _null_ _null_ ));
DESCR("test XML value against XPath expression");
+ DATA(insert OID = 3037 ( xpath_exists PGNSP PGUID 12 1 0 0 f f f t f i 3 0 16 "25 142 1009" _null_ _null_ _null_ _null_ xpath_exists _null_ _null_ _null_ ));
+ DESCR("evaluate XPath expression in a boolean context, with namespaces support");
+ DATA(insert OID = 3038 ( xpath_exists PGNSP PGUID 14 1 0 0 f f f t f i 2 0 16 "25 142" _null_ _null_ _null_ _null_ "select pg_catalog.xpath_exists($1, $2, ''{}''::pg_catalog.text[])" _null_ _null_ _null_ ));
+ DESCR("evaluate XPath expression in a boolean context");
+
/* uuid */
DATA(insert OID = 2952 ( uuid_in PGNSP PGUID 12 1 0 0 f f f t f i 1 0 2950 "2275" _null_ _null_ _null_ _null_ uuid_in _null_ _null_ _null_ ));
DESCR("I/O");
*** a/src/include/utils/xml.h
--- b/src/include/utils/xml.h
***************
*** 37,42 **** extern Datum texttoxml(PG_FUNCTION_ARGS);
--- 37,43 ----
extern Datum xmltotext(PG_FUNCTION_ARGS);
extern Datum xmlvalidate(PG_FUNCTION_ARGS);
extern Datum xpath(PG_FUNCTION_ARGS);
+ extern Datum xpath_exists(PG_FUNCTION_ARGS);
extern Datum xmlexists(PG_FUNCTION_ARGS);
extern Datum table_to_xml(PG_FUNCTION_ARGS);
*** a/src/test/regress/expected/xml.out
--- b/src/test/regress/expected/xml.out
***************
*** 502,507 **** SELECT xpath('//b', '<a>one <b>two</b> three <b>etc</b></a>');
--- 502,560 ----
{<b>two</b>,<b>etc</b>}
(1 row)
+ -- Test xpath_exists evaluation
+ SELECT xpath_exists('//town[text() = ''Toronto'']','<towns><town>Bidford-on-Avon</town><town>Cwmbran</town><town>Bristol</town></towns>'::xml);
+ xpath_exists
+ --------------
+ f
+ (1 row)
+
+ SELECT xpath_exists('//town[text() = ''Cwmbran'']','<towns><town>Bidford-on-Avon</town><town>Cwmbran</town><town>Bristol</town></towns>'::xml);
+ xpath_exists
+ --------------
+ t
+ (1 row)
+
+ INSERT INTO xmltest VALUES (4, '<menu><beers><name>Budvar</name><cost>free</cost><name>Carling</name><cost>lots</cost></beers></menu>'::xml);
+ INSERT INTO xmltest VALUES (5, '<menu><beers><name>Molson</name><cost>free</cost><name>Carling</name><cost>lots</cost></beers></menu>'::xml);
+ INSERT INTO xmltest VALUES (6, '<myns:menu xmlns:myns="http://myns.com";><myns:beers><myns:name>Budvar</myns:name><myns:cost>free</myns:cost><myns:name>Carling</myns:name><myns:cost>lots</myns:cost></myns:beers></myns:menu>'::xml);
+ INSERT INTO xmltest VALUES (7, '<myns:menu xmlns:myns="http://myns.com";><myns:beers><myns:name>Molson</myns:name><myns:cost>free</myns:cost><myns:name>Carling</myns:name><myns:cost>lots</myns:cost></myns:beers></myns:menu>'::xml);
+ SELECT COUNT(id) FROM xmltest WHERE xpath_exists('/menu/beer',data);
+ count
+ -------
+ 0
+ (1 row)
+
+ SELECT COUNT(id) FROM xmltest WHERE xpath_exists('/menu/beers',data);
+ count
+ -------
+ 2
+ (1 row)
+
+ SELECT COUNT(id) FROM xmltest WHERE xpath_exists('/menu/beers/name[text() = ''Molson'']',data);
+ count
+ -------
+ 1
+ (1 row)
+
+ SELECT COUNT(id) FROM xmltest WHERE xpath_exists('/myns:menu/myns:beer',data,ARRAY[ARRAY['myns','http://myns.com']]);
+ count
+ -------
+ 0
+ (1 row)
+
+ SELECT COUNT(id) FROM xmltest WHERE xpath_exists('/myns:menu/myns:beers',data,ARRAY[ARRAY['myns','http://myns.com']]);
+ count
+ -------
+ 2
+ (1 row)
+
+ SELECT COUNT(id) FROM xmltest WHERE xpath_exists('/myns:menu/myns:beers/myns:name[text() = ''Molson'']',data,ARRAY[ARRAY['myns','http://myns.com']]);
+ count
+ -------
+ 1
+ (1 row)
+
-- Test xmlexists evaluation
SELECT xmlexists('//town[text() = ''Toronto'']' PASSING BY REF '<towns><town>Bidford-on-Avon</town><town>Cwmbran</town><town>Bristol</town></towns>');
xmlexists
***************
*** 515,524 **** SELECT xmlexists('//town[text() = ''Cwmbran'']' PASSING BY REF '<towns><town>Bid
t
(1 row)
- INSERT INTO xmltest VALUES (4, '<menu><beers><name>Budvar</name><cost>free</cost><name>Carling</name><cost>lots</cost></beers></menu>'::xml);
- INSERT INTO xmltest VALUES (5, '<menu><beers><name>Molson</name><cost>free</cost><name>Carling</name><cost>lots</cost></beers></menu>'::xml);
- INSERT INTO xmltest VALUES (6, '<myns:menu xmlns:myns="http://myns.com";><myns:beers><myns:name>Budvar</myns:name><myns:cost>free</myns:cost><myns:name>Carling</myns:name><myns:cost>lots</myns:cost></myns:beers></myns:menu>'::xml);
- INSERT INTO xmltest VALUES (7, '<myns:menu xmlns:myns="http://myns.com";><myns:beers><myns:name>Molson</myns:name><myns:cost>free</myns:cost><myns:name>Carling</myns:name><myns:cost>lots</myns:cost></myns:beers></myns:menu>'::xml);
SELECT COUNT(id) FROM xmltest WHERE xmlexists('/menu/beer' PASSING data);
count
-------
--- 568,573 ----
*** a/src/test/regress/sql/xml.sql
--- b/src/test/regress/sql/xml.sql
***************
*** 164,178 **** SELECT xpath('//text()', '<local:data xmlns:local="http://127.0.0.1";><local:piec
SELECT xpath('//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', 'http://127.0.0.1']]);
SELECT xpath('//b', '<a>one <b>two</b> three <b>etc</b></a>');
! -- Test xmlexists evaluation
! SELECT xmlexists('//town[text() = ''Toronto'']' PASSING BY REF '<towns><town>Bidford-on-Avon</town><town>Cwmbran</town><town>Bristol</town></towns>');
! SELECT xmlexists('//town[text() = ''Cwmbran'']' PASSING BY REF '<towns><town>Bidford-on-Avon</town><town>Cwmbran</town><town>Bristol</town></towns>');
INSERT INTO xmltest VALUES (4, '<menu><beers><name>Budvar</name><cost>free</cost><name>Carling</name><cost>lots</cost></beers></menu>'::xml);
INSERT INTO xmltest VALUES (5, '<menu><beers><name>Molson</name><cost>free</cost><name>Carling</name><cost>lots</cost></beers></menu>'::xml);
INSERT INTO xmltest VALUES (6, '<myns:menu xmlns:myns="http://myns.com";><myns:beers><myns:name>Budvar</myns:name><myns:cost>free</myns:cost><myns:name>Carling</myns:name><myns:cost>lots</myns:cost></myns:beers></myns:menu>'::xml);
INSERT INTO xmltest VALUES (7, '<myns:menu xmlns:myns="http://myns.com";><myns:beers><myns:name>Molson</myns:name><myns:cost>free</myns:cost><myns:name>Carling</myns:name><myns:cost>lots</myns:cost></myns:beers></myns:menu>'::xml);
SELECT COUNT(id) FROM xmltest WHERE xmlexists('/menu/beer' PASSING data);
SELECT COUNT(id) FROM xmltest WHERE xmlexists('/menu/beer' PASSING BY REF data BY REF);
--- 164,188 ----
SELECT xpath('//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', 'http://127.0.0.1']]);
SELECT xpath('//b', '<a>one <b>two</b> three <b>etc</b></a>');
! -- Test xpath_exists evaluation
! SELECT xpath_exists('//town[text() = ''Toronto'']','<towns><town>Bidford-on-Avon</town><town>Cwmbran</town><town>Bristol</town></towns>'::xml);
! SELECT xpath_exists('//town[text() = ''Cwmbran'']','<towns><town>Bidford-on-Avon</town><town>Cwmbran</town><town>Bristol</town></towns>'::xml);
INSERT INTO xmltest VALUES (4, '<menu><beers><name>Budvar</name><cost>free</cost><name>Carling</name><cost>lots</cost></beers></menu>'::xml);
INSERT INTO xmltest VALUES (5, '<menu><beers><name>Molson</name><cost>free</cost><name>Carling</name><cost>lots</cost></beers></menu>'::xml);
INSERT INTO xmltest VALUES (6, '<myns:menu xmlns:myns="http://myns.com";><myns:beers><myns:name>Budvar</myns:name><myns:cost>free</myns:cost><myns:name>Carling</myns:name><myns:cost>lots</myns:cost></myns:beers></myns:menu>'::xml);
INSERT INTO xmltest VALUES (7, '<myns:menu xmlns:myns="http://myns.com";><myns:beers><myns:name>Molson</myns:name><myns:cost>free</myns:cost><myns:name>Carling</myns:name><myns:cost>lots</myns:cost></myns:beers></myns:menu>'::xml);
+ SELECT COUNT(id) FROM xmltest WHERE xpath_exists('/menu/beer',data);
+ SELECT COUNT(id) FROM xmltest WHERE xpath_exists('/menu/beers',data);
+ SELECT COUNT(id) FROM xmltest WHERE xpath_exists('/menu/beers/name[text() = ''Molson'']',data);
+ SELECT COUNT(id) FROM xmltest WHERE xpath_exists('/myns:menu/myns:beer',data,ARRAY[ARRAY['myns','http://myns.com']]);
+ SELECT COUNT(id) FROM xmltest WHERE xpath_exists('/myns:menu/myns:beers',data,ARRAY[ARRAY['myns','http://myns.com']]);
+ SELECT COUNT(id) FROM xmltest WHERE xpath_exists('/myns:menu/myns:beers/myns:name[text() = ''Molson'']',data,ARRAY[ARRAY['myns','http://myns.com']]);
+
+ -- Test xmlexists evaluation
+ SELECT xmlexists('//town[text() = ''Toronto'']' PASSING BY REF '<towns><town>Bidford-on-Avon</town><town>Cwmbran</town><town>Bristol</town></towns>');
+ SELECT xmlexists('//town[text() = ''Cwmbran'']' PASSING BY REF '<towns><town>Bidford-on-Avon</town><town>Cwmbran</town><town>Bristol</town></towns>');
SELECT COUNT(id) FROM xmltest WHERE xmlexists('/menu/beer' PASSING data);
SELECT COUNT(id) FROM xmltest WHERE xmlexists('/menu/beer' PASSING BY REF data BY REF);
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