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  1. Fix some whitespace issues in XMLSERIALIZE(... INDENT).

  1. [BUG?] XMLSERIALIZE( ... INDENT) won't work with blank nodes

    Jim Jones <jim.jones@uni-muenster.de> — 2024-08-28T08:19:48Z

    Hi,

While testing a feature reported by Pavel in this thread[1] I realized
that elements containing whitespaces between them won't be indented with
XMLSERIALIZE( ... INDENT)

SELECT xmlserialize(DOCUMENT '<foo><bar>42</bar></foo>' AS text INDENT);

  xmlserialize   
-----------------
 <foo>          +
   <bar>42</bar>+
 </foo>         +
 
(1 row)

SELECT xmlserialize(DOCUMENT '<foo> <bar>42</bar> </foo>'::xml AS text
INDENT);
        xmlserialize        
----------------------------
 <foo> <bar>42</bar> </foo>+
 
(1 row)


Other products have a different approach[2]

Perhaps simply setting xmltotext_with_options' parameter "perserve_whitespace" to false when XMLSERIALIZE(.. INDENT) would do the trick.

doc = xml_parse(data, xmloption_arg, !indent ? true : false,
			GetDatabaseEncoding(),
			&parsed_xmloptiontype, &content_nodes,
			(Node *) &escontext);


(diff attached)

SELECT xmlserialize(DOCUMENT '<foo> <bar>42</bar> </foo>'::xml AS text
INDENT);
  xmlserialize   
-----------------
 <foo>          +
   <bar>42</bar>+
 </foo>         +
 
(1 row)

If this is indeed the way to go I can update the regression tests accordingly.

Best,

-- 
Jim

1 - https://www.postgresql.org/message-id/cbd68a31-9776-4742-9c09-4344a4c5e6dc%40uni-muenster.de
2 - https://dbfiddle.uk/zdKnfsqX

  2. Re: [BUG?] XMLSERIALIZE( ... INDENT) won't work with blank nodes

    Jim Jones <jim.jones@uni-muenster.de> — 2024-08-29T22:06:46Z

    
On 28.08.24 10:19, Jim Jones wrote:
> Hi,
>
> While testing a feature reported by Pavel in this thread[1] I realized
> that elements containing whitespaces between them won't be indented with
> XMLSERIALIZE( ... INDENT)
>
> SELECT xmlserialize(DOCUMENT '<foo><bar>42</bar></foo>' AS text INDENT);
>
>   xmlserialize   
> -----------------
>  <foo>          +
>    <bar>42</bar>+
>  </foo>         +
>  
> (1 row)
>
> SELECT xmlserialize(DOCUMENT '<foo> <bar>42</bar> </foo>'::xml AS text
> INDENT);
>         xmlserialize        
> ----------------------------
>  <foo> <bar>42</bar> </foo>+
>  
> (1 row)
>
>
> Other products have a different approach[2]
>
> Perhaps simply setting xmltotext_with_options' parameter "perserve_whitespace" to false when XMLSERIALIZE(.. INDENT) would do the trick.
>
> doc = xml_parse(data, xmloption_arg, !indent ? true : false,
> 			GetDatabaseEncoding(),
> 			&parsed_xmloptiontype, &content_nodes,
> 			(Node *) &escontext);
>
>
> (diff attached)
>
> SELECT xmlserialize(DOCUMENT '<foo> <bar>42</bar> </foo>'::xml AS text
> INDENT);
>   xmlserialize   
> -----------------
>  <foo>          +
>    <bar>42</bar>+
>  </foo>         +
>  
> (1 row)
>
> If this is indeed the way to go I can update the regression tests accordingly.
>
> Best,
>

Just created a CF entry for this: https://commitfest.postgresql.org/49/5217/
v1 attached includes regression tests.

-- 
Jim

  3. Re: [BUG?] XMLSERIALIZE( ... INDENT) won't work with blank nodes

    Jim Jones <jim.jones@uni-muenster.de> — 2024-09-06T11:55:06Z

    
On 28.08.24 10:19, Jim Jones wrote:
> Hi,
>
> While testing a feature reported by Pavel in this thread[1] I realized
> that elements containing whitespaces between them won't be indented with
> XMLSERIALIZE( ... INDENT)
>

mmh... xmlDocContentDumpOutput seems to add a trailing newline in the
end of a document by default, making the serialization of the same xml
string with DOCUMENT and CONTENT different:

-- postgres v16

SELECT xmlserialize(CONTENT '<foo><bar>42</bar></foo>' AS text INDENT);
  xmlserialize   
-----------------
 <foo>          +
   <bar>42</bar>+
 </foo>
(1 row)

SELECT xmlserialize(DOCUMENT '<foo><bar>42</bar></foo>' AS text INDENT);
  xmlserialize   
-----------------
 <foo>          +
   <bar>42</bar>+
 </foo>         +
 
(1 row)


I do recall a discussion along these lines some time ago, but I just
can't find it now. Does anyone know if this is the expected behaviour?
Or should we in this case consider something like this in
xmltotext_with_options()?

result = cstring_to_text_with_len((const char *) xmlBufferContent(buf),
xmlBufferLength(buf) - 1);

-- 
Jim

  4. Re: [BUG?] XMLSERIALIZE( ... INDENT) won't work with blank nodes

    Tom Lane <tgl@sss.pgh.pa.us> — 2024-09-06T16:34:04Z

    Jim Jones <jim.jones@uni-muenster.de> writes:
> mmh... xmlDocContentDumpOutput seems to add a trailing newline in the
> end of a document by default, making the serialization of the same xml
> string with DOCUMENT and CONTENT different:

Does seem a bit inconsistent.

> Or should we in this case consider something like this in
> xmltotext_with_options()?
> result = cstring_to_text_with_len((const char *) xmlBufferContent(buf),
> xmlBufferLength(buf) - 1);

I think it'd be quite foolish to assume that every extant and future
version of libxml2 will share this glitch.  Probably should use
logic more like pg_strip_crlf(), although we can't use that directly.

Would it ever be the case that trailing whitespace would be valid
data?  In a bit of testing, it seems like that could be true in
CONTENT mode but not DOCUMENT mode.

			regards, tom lane

  5. Re: [BUG?] XMLSERIALIZE( ... INDENT) won't work with blank nodes

    Jim Jones <jim.jones@uni-muenster.de> — 2024-09-06T22:46:06Z

    Hi Tom

On 06.09.24 18:34, Tom Lane wrote:
> I think it'd be quite foolish to assume that every extant and future
> version of libxml2 will share this glitch.  Probably should use
> logic more like pg_strip_crlf(), although we can't use that directly.
Makes sense. I Introduced this logic in the end of
xmltotext_with_options() in case it was called with INDENT and DOCUMENT
type xml string.

SELECT xmlserialize(DOCUMENT '<foo><bar>42</bar></foo>' AS text INDENT);
  xmlserialize   
-----------------
 <foo>          +
   <bar>42</bar>+
 </foo>
(1 row)

The regression tests were updated accordingly - see patch v2-0002.
> Would it ever be the case that trailing whitespace would be valid
> data?  In a bit of testing, it seems like that could be true in
> CONTENT mode but not DOCUMENT mode.
Yes, in case of CONTENT it is valid data and it will be preserved, as
CONTENT can be pretty much anything.

SELECT xmlserialize(CONTENT E'<foo><bar>42</bar></foo>\n\n\t\t\t' AS
text INDENT);
       xmlserialize       
--------------------------
 <foo>                   +
   <bar>42</bar>         +
 </foo>                  +
                         +
                         
(1 row)


With DOCUMENT it is superfluous and should be removed after indentation.
IIRC there's an xmlSaveToBuffer option called XML_SAVE_WSNONSIG that can
be used to preserve it.

Thanks

Best, Jim

  6. Re: [BUG?] XMLSERIALIZE( ... INDENT) won't work with blank nodes

    Tom Lane <tgl@sss.pgh.pa.us> — 2024-09-10T20:24:43Z

    Jim Jones <jim.jones@uni-muenster.de> writes:
> [ xmlserialize patches ]

Pushed with minor editorialization.  Notably, I got rid of scribbling
on xmlBufferContent's buffer --- I don't know how likely that is to
upset libxml2, but it seems like a fairly bad idea given that they
declare the result as "const xmlChar*".  Casting away the const is
poor form in any case.

			regards, tom lane