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Add XMLNamespaces option to XMLElement
This patch adds support for the scoped option XMLNamespaces in the XMLElement() function, as specified in ISO/IEC 9075-14:2023, section 11.2, "XML lexically scoped options". The XMLNamespaces clause allows users to declare XML namespace prefixes and a default namespace within the scope of an XMLElement() call. These declarations affect both the constructed element and its content, enabling generation of namespaced XML content in a standards-compliant way. == Syntax == xmlnamespaces(uri AS prefix, ...) xmlnamespaces(DEFAULT uri, ...) xmlnamespaces(NO DEFAULT, ...) * prefix: Namespace prefix to associate with the URI * uri: The namespace URI * DEFAULT uri: Specifies the default namespace within the scope * NO DEFAULT: Specifies that no default namespace is in effect == Examples == SELECT xmlelement(NAME "foo", xmlnamespaces('http:/x.y' AS bar)); SELECT xmlelement(NAME "foo", xmlnamespaces(DEFAULT 'http:/x.y')); SELECT xmlelement(NAME "foo", xmlnamespaces(NO DEFAULT)); This feature enables standards-compliant construction of namespaced XML directly from SQL, improving interoperability with XML-based applications and document workflows. Author: Jim Jones <jim.jones@uni-muenster.de> Co-Authored-by: Pavel Stehule <pavel.stehule@gmail.com> Reviewed-by: Umar Hayat <postgresql.wizard@gmail.com> Reviewed-by: newtglobal postgresql_contributors <postgresql_contributors@newtglobalcorp.com> Discussion: https://www.postgresql.org/message-id/flat/237def1a-e318-40fa-baa3-0e3195be564e%40uni-muenster.de
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10 files changed

Lines changed: 787 additions & 39 deletions

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‎doc/src/sgml/func/func-xml.sgml‎

Lines changed: 54 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -158,7 +158,10 @@ SELECT xmlconcat('<?xml version="1.1"?><foo/>', '<?xml version="1.1" standalone=
158158
</indexterm>
159159

160160
<synopsis>
161-
<function>xmlelement</function> ( <literal>NAME</literal> <replaceable>name</replaceable> <optional>, <literal>XMLATTRIBUTES</literal> ( <replaceable>attvalue</replaceable> <optional> <literal>AS</literal> <replaceable>attname</replaceable> </optional> <optional>, ...</optional> ) </optional> <optional>, <replaceable>content</replaceable> <optional>, ...</optional></optional> ) <returnvalue>xml</returnvalue>
161+
<function>xmlelement</function> ( <literal>NAME</literal> <replaceable>name</replaceable>
162+
<optional>, <literal>XMLATTRIBUTES</literal> ( <replaceable>attvalue</replaceable> <optional> <literal>AS</literal> <replaceable>attname</replaceable> </optional> <optional>, ...</optional> ) </optional>
163+
<optional>, <literal>XMLNAMESPACES</literal> ( {<replaceable>regular-nsuri</replaceable> <literal>AS</literal> <replaceable>nsprefix</replaceable> | DEFAULT <replaceable>default-nsuri</replaceable> | NO DEFAULT} <optional>, ...</optional> ) </optional>
164+
<optional>, <replaceable>content</replaceable> <optional>, ...</optional></optional> ) <returnvalue>xml</returnvalue>
162165
</synopsis>
163166

164167
<para>
@@ -171,9 +174,40 @@ SELECT xmlconcat('<?xml version="1.1"?><foo/>', '<?xml version="1.1" standalone=
171174
yield any <productname>PostgreSQL</productname> data type. The
172175
argument(s) within <literal>XMLATTRIBUTES</literal> generate attributes
173176
of the XML element; the <replaceable>content</replaceable> value(s) are
174-
concatenated to form its content.
177+
concatenated to form its content. The arguments within <literal>XMLNAMESPACES</literal>
178+
construct namespace declarations from values provided in <replaceable>nsuri</replaceable>
179+
and <replaceable>nsprefix</replaceable>, which correspond to the URI of a namespace and
180+
its prefix, respectively. The option <literal>DEFAULT</literal> can be used to set the
181+
default namespace declaration (without a prefix) to the URI provided in <replaceable>default-nsuri</replaceable>.
182+
The option <literal>NO DEFAULT</literal> states that a namespace scope has no default namespace. A valid
183+
<literal>XMLNAMESPACES</literal> item must fulfill the following conditions:
175184
</para>
176185

186+
<itemizedlist>
187+
<listitem>
188+
<para>
189+
Only a single <literal>DEFAULT</literal> declaration item within the same scope.
190+
</para>
191+
</listitem>
192+
<listitem>
193+
<para>
194+
No two <replaceable>nsprefix</replaceable> values can be equal within the same scope.
195+
</para>
196+
</listitem>
197+
<listitem>
198+
<para>
199+
No <replaceable>nsprefix</replaceable> can be equal to <literal>xml</literal> or <literal>xmlns</literal>,
200+
and no <replaceable>nsuri</replaceable> can be equal to <literal>http://www.w3.org/2000/xmlns/</literal>
201+
or to <literal>http://www.w3.org/XML/1998/namespace</literal>, as they are already bound to standard XML declarations.
202+
</para>
203+
</listitem>
204+
<listitem>
205+
<para>
206+
The value of a <replaceable>regular-nsuri</replaceable> cannot be a zero-length string.
207+
</para>
208+
</listitem>
209+
</itemizedlist>
210+
177211
<para>
178212
Examples:
179213
<screen><![CDATA[
@@ -194,6 +228,24 @@ SELECT xmlelement(NAME foo, xmlattributes(current_date AS bar), 'cont', 'ent');
194228
xmlelement
195229
-------------------------------------
196230
<foo bar="2007-01-26">content</foo>
231+
232+
SELECT xmlelement(NAME "foo:root", xmlnamespaces('http:/foo.bar/' AS foo), 'content');
233+
234+
xmlelement
235+
---------------------------------------------------------
236+
<foo:root xmlns:foo="http:/foo.bar/">content</foo:root>
237+
238+
SELECT xmlelement(NAME "root", xmlnamespaces(DEFAULT 'http:/foo.bar/'), 'content');
239+
240+
xmlelement
241+
---------------------------------------------
242+
<root xmlns="http:/foo.bar/">content</root>
243+
244+
SELECT xmlelement(NAME "root", xmlnamespaces(NO DEFAULT), 'content');
245+
246+
xmlelement
247+
-------------------------------
248+
<root xmlns="">content</root>
197249
]]></screen>
198250
</para>
199251

‎src/backend/parser/gram.y‎

Lines changed: 84 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -136,6 +136,12 @@ typedef struct KeyActions
136136
KeyAction *deleteAction;
137137
} KeyActions;
138138

139+
typedef struct XmlElementOpts
140+
{
141+
List *xml_attributes;
142+
List *xml_namespaces;
143+
} XmlElementOpts;
144+
139145
/* ConstraintAttributeSpec yields an integer bitmask of these flags: */
140146
#define CAS_NOT_DEFERRABLE 0x01
141147
#define CAS_DEFERRABLE 0x02
@@ -186,7 +192,7 @@ static Node *makeNotExpr(Node *expr, int location);
186192
static Node *makeAArrayExpr(List *elements, int location, int location_end);
187193
static Node *makeSQLValueFunction(SQLValueFunctionOp op, int32 typmod,
188194
int location);
189-
static Node *makeXmlExpr(XmlExprOp op, char *name, List *named_args,
195+
static Node *makeXmlExpr(XmlExprOp op, char *name, XmlElementOpts *opts,
190196
List *args, int location);
191197
static List *mergeTableFuncParameters(List *func_args, List *columns, core_yyscan_t yyscanner);
192198
static TypeName *TableFuncTypeName(List *columns);
@@ -273,6 +279,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
273279
MergeWhenClause *mergewhen;
274280
struct KeyActions *keyactions;
275281
struct KeyAction *keyaction;
282+
struct XmlElementOpts *xmlelementopts;
276283
ReturningClause *retclause;
277284
ReturningOptionKind retoptionkind;
278285
}
@@ -631,8 +638,9 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
631638
%type <list> xmltable_column_list xmltable_column_option_list
632639
%type <node> xmltable_column_el
633640
%type <defelt> xmltable_column_option_el
634-
%type <list> xml_namespace_list
641+
%type <list> xml_namespace_list xml_namespaces
635642
%type <target> xml_namespace_el
643+
%type <xmlelementopts> xmlelement_opts
636644

637645
%type <node> func_application func_expr_common_subexpr
638646
%type <node> func_expr func_expr_windowless
@@ -15179,6 +15187,15 @@ xml_namespace_el:
1517915187
$$->val = $2;
1518015188
$$->location = @1;
1518115189
}
15190+
| NO DEFAULT
15191+
{
15192+
$$ = makeNode(ResTarget);
15193+
$$->name = NULL;
15194+
$$->indirection = NIL;
15195+
$$->val = NULL;
15196+
$$->location = @1;
15197+
}
15198+
1518215199
;
1518315200

1518415201
json_table:
@@ -16328,12 +16345,12 @@ a_expr: c_expr { $$ = $1; }
1632816345
}
1632916346
| a_expr IS DOCUMENT_P %prec IS
1633016347
{
16331-
$$ = makeXmlExpr(IS_DOCUMENT, NULL, NIL,
16348+
$$ = makeXmlExpr(IS_DOCUMENT, NULL, NULL,
1633216349
list_make1($1), @2);
1633316350
}
1633416351
| a_expr IS NOT DOCUMENT_P %prec IS
1633516352
{
16336-
$$ = makeNotExpr(makeXmlExpr(IS_DOCUMENT, NULL, NIL,
16353+
$$ = makeNotExpr(makeXmlExpr(IS_DOCUMENT, NULL, NULL,
1633716354
list_make1($1), @2),
1633816355
@2);
1633916356
}
@@ -16483,12 +16500,12 @@ b_expr: c_expr
1648316500
}
1648416501
| b_expr IS DOCUMENT_P %prec IS
1648516502
{
16486-
$$ = makeXmlExpr(IS_DOCUMENT, NULL, NIL,
16503+
$$ = makeXmlExpr(IS_DOCUMENT, NULL, NULL,
1648716504
list_make1($1), @2);
1648816505
}
1648916506
| b_expr IS NOT DOCUMENT_P %prec IS
1649016507
{
16491-
$$ = makeNotExpr(makeXmlExpr(IS_DOCUMENT, NULL, NIL,
16508+
$$ = makeNotExpr(makeXmlExpr(IS_DOCUMENT, NULL, NULL,
1649216509
list_make1($1), @2),
1649316510
@2);
1649416511
}
@@ -17024,21 +17041,21 @@ func_expr_common_subexpr:
1702417041
}
1702517042
| XMLCONCAT '(' expr_list ')'
1702617043
{
17027-
$$ = makeXmlExpr(IS_XMLCONCAT, NULL, NIL, $3, @1);
17044+
$$ = makeXmlExpr(IS_XMLCONCAT, NULL, NULL, $3, @1);
1702817045
}
1702917046
| XMLELEMENT '(' NAME_P ColLabel ')'
1703017047
{
17031-
$$ = makeXmlExpr(IS_XMLELEMENT, $4, NIL, NIL, @1);
17048+
$$ = makeXmlExpr(IS_XMLELEMENT, $4, NULL, NIL, @1);
1703217049
}
17033-
| XMLELEMENT '(' NAME_P ColLabel ',' xml_attributes ')'
17050+
| XMLELEMENT '(' NAME_P ColLabel ',' xmlelement_opts ')'
1703417051
{
1703517052
$$ = makeXmlExpr(IS_XMLELEMENT, $4, $6, NIL, @1);
1703617053
}
1703717054
| XMLELEMENT '(' NAME_P ColLabel ',' expr_list ')'
1703817055
{
17039-
$$ = makeXmlExpr(IS_XMLELEMENT, $4, NIL, $6, @1);
17056+
$$ = makeXmlExpr(IS_XMLELEMENT, $4, NULL, $6, @1);
1704017057
}
17041-
| XMLELEMENT '(' NAME_P ColLabel ',' xml_attributes ',' expr_list ')'
17058+
| XMLELEMENT '(' NAME_P ColLabel ',' xmlelement_opts ',' expr_list ')'
1704217059
{
1704317060
$$ = makeXmlExpr(IS_XMLELEMENT, $4, $6, $8, @1);
1704417061
}
@@ -17053,12 +17070,17 @@ func_expr_common_subexpr:
1705317070
}
1705417071
| XMLFOREST '(' labeled_expr_list ')'
1705517072
{
17056-
$$ = makeXmlExpr(IS_XMLFOREST, NULL, $3, NIL, @1);
17073+
XmlElementOpts *opts = palloc(sizeof(XmlElementOpts));
17074+
17075+
opts->xml_attributes = $3;
17076+
opts->xml_namespaces = NIL;
17077+
17078+
$$ = makeXmlExpr(IS_XMLFOREST, NULL, opts, NIL, @1);
1705717079
}
1705817080
| XMLPARSE '(' document_or_content a_expr xml_whitespace_option ')'
1705917081
{
1706017082
XmlExpr *x = (XmlExpr *)
17061-
makeXmlExpr(IS_XMLPARSE, NULL, NIL,
17083+
makeXmlExpr(IS_XMLPARSE, NULL, NULL,
1706217084
list_make2($4, makeBoolAConst($5, -1)),
1706317085
@1);
1706417086

@@ -17075,7 +17097,7 @@ func_expr_common_subexpr:
1707517097
}
1707617098
| XMLROOT '(' a_expr ',' xml_root_version opt_xml_root_standalone ')'
1707717099
{
17078-
$$ = makeXmlExpr(IS_XMLROOT, NULL, NIL,
17100+
$$ = makeXmlExpr(IS_XMLROOT, NULL, NULL,
1707917101
list_make3($3, $5, $6), @1);
1708017102
}
1708117103
| XMLSERIALIZE '(' document_or_content a_expr AS SimpleTypename xml_indent_option ')'
@@ -17279,6 +17301,9 @@ opt_xml_root_standalone: ',' STANDALONE_P YES_P
1727917301
xml_attributes: XMLATTRIBUTES '(' labeled_expr_list ')' { $$ = $3; }
1728017302
;
1728117303

17304+
xml_namespaces: XMLNAMESPACES '(' xml_namespace_list ')' { $$ = $3; }
17305+
;
17306+
1728217307
labeled_expr_list: labeled_expr { $$ = list_make1($1); }
1728317308
| labeled_expr_list ',' labeled_expr { $$ = lappend($1, $3); }
1728417309
;
@@ -17315,6 +17340,44 @@ xml_whitespace_option: PRESERVE WHITESPACE_P { $$ = true; }
1731517340
| /*EMPTY*/ { $$ = false; }
1731617341
;
1731717342

17343+
xmlelement_opts: xml_attributes
17344+
{
17345+
XmlElementOpts *n = palloc(sizeof(XmlElementOpts));
17346+
17347+
n->xml_attributes = $1;
17348+
n->xml_namespaces = NIL;
17349+
$$ = n;
17350+
}
17351+
| xml_namespaces
17352+
{
17353+
XmlElementOpts *n = palloc(sizeof(XmlElementOpts));
17354+
17355+
n->xml_attributes = NIL;
17356+
n->xml_namespaces = $1;
17357+
$$ = n;
17358+
}
17359+
| xmlelement_opts ',' xml_attributes
17360+
{
17361+
if ($$->xml_attributes)
17362+
ereport(ERROR,
17363+
(errcode(ERRCODE_SYNTAX_ERROR),
17364+
errmsg("duplicate XMLATTRIBUTES specified"),
17365+
parser_errposition(@3)));
17366+
17367+
$$->xml_attributes = $3;
17368+
}
17369+
| xmlelement_opts ',' xml_namespaces
17370+
{
17371+
if ($$->xml_namespaces)
17372+
ereport(ERROR,
17373+
(errcode(ERRCODE_SYNTAX_ERROR),
17374+
errmsg("duplicate XMLNAMESPACES specified"),
17375+
parser_errposition(@3)));
17376+
17377+
$$->xml_namespaces = $3;
17378+
}
17379+
;
17380+
1731817381
/* We allow several variants for SQL and other compatibility. */
1731917382
xmlexists_argument:
1732017383
PASSING c_expr
@@ -20505,7 +20568,7 @@ makeSQLValueFunction(SQLValueFunctionOp op, int32 typmod, int location)
2050520568
}
2050620569

2050720570
static Node *
20508-
makeXmlExpr(XmlExprOp op, char *name, List *named_args, List *args,
20571+
makeXmlExpr(XmlExprOp op, char *name, XmlElementOpts *opts, List *args,
2050920572
int location)
2051020573
{
2051120574
XmlExpr *x = makeNode(XmlExpr);
@@ -20517,7 +20580,12 @@ makeXmlExpr(XmlExprOp op, char *name, List *named_args, List *args,
2051720580
* named_args is a list of ResTarget; it'll be split apart into separate
2051820581
* expression and name lists in transformXmlExpr().
2051920582
*/
20520-
x->named_args = named_args;
20583+
if (opts)
20584+
{
20585+
x->named_args = opts->xml_attributes;
20586+
x->xmlnamespaces = opts->xml_namespaces;
20587+
}
20588+
2052120589
x->arg_names = NIL;
2052220590
x->args = args;
2052320591
/* xmloption, if relevant, must be filled in by caller */

‎src/backend/parser/parse_clause.c‎

Lines changed: 9 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -848,7 +848,15 @@ transformRangeTableFunc(ParseState *pstate, RangeTableFunc *rtf)
848848
Node *ns_uri;
849849

850850
Assert(IsA(r, ResTarget));
851-
ns_uri = transformExpr(pstate, r->val, EXPR_KIND_FROM_FUNCTION);
851+
852+
if (!r->name && !r->val)
853+
{
854+
/* Create an empty string for NO DEFAULT namespaces */
855+
ns_uri = transformExpr(pstate, makeStringConst("", r->location), EXPR_KIND_FROM_FUNCTION);
856+
}
857+
else
858+
ns_uri = transformExpr(pstate, r->val, EXPR_KIND_FROM_FUNCTION);
859+
852860
ns_uri = coerce_to_specific_type(pstate, ns_uri,
853861
TEXTOID, constructName);
854862
assign_expr_collations(pstate, ns_uri);

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