Re: [gnome-db] sql extension to libxslt using libgda.

[Paweł Cesar Sanjuan Szklarz <paweld2 gmail com>]

Hi.

Dnia 11-09-2007, wto o godzinie 11:45 +0200, Vivien Malerba napisał(a):
> This is an interresting piece of work. Tell me if I'm wrong (I'm no
> XSLT expert), but here is how I understand it: the code you show here
> is an extension which can be used with the libxslt library, declared
> as such to the libxslt library (using xsltRegisterExtModule()).

Yes.
Libxslt dont have dinamical load of libraries for the extensions, so the
code that calls xsltRegisterExtModule() have to be access to the
extension init/finalize functions (of course,when linking the code).

> 
> As you might expect, I have a few questions/remarks:
> * (not strictly related to your code) is it related to libxslt or to
> Libexslt (http://xmlsoft.org/XSLT/EXSLT/index.html)?
This extension use only libxslt. libexslt use the same api that I am
using.

The diference with libexslt and my extension, is that the extensions
from libexslt are alreally declared on libxslt.

> * how should libgda make that extension available (if the libxslt
> framework is generic enough, I would prefer not add some extra API
> such as sqlxslt_process_xslt_file_ext(), to rely as much as possible
> to libxslt's own API)?
sqlxslt_process_xslt_file_ext() is just a test function, it can be drop
from the library.

>  Would it be possible for example to have only 2
> calls like:
>    xsltTransformContextPtr *gda_xslt_create_context (GdaConnection *cnc)
>    xsltTransformContextPtr *gda_xslt_create_context_with_dict (GdaDict *dict)
>   and then let the user use that transform context as he would for any
> other tranform context?
 The API from libgda depends on what extension elements and functions
you want to have.
For example, it is posible to have a sql:configuration node like this:
<xsl:template match="/">
<sql:configuration>
  <sql:dns>dnstest</sql:dns>
</sql:configuration>
.........
</xsl:template>
that set the database configuration inside the
XSLTTransformationContext.
Then you just need from libgda a function like this:
   void gda_xslt_register_sql_extension(GError **error);

The real question about a API from libgda is:
What elements and functions extension we want to implement??

!!!!!!!!
Each elem/func extension needs a backend function on libgda.
!!!!!!!!

Maybe a <sql:command> to run GdaCommand queries.
<sql:configuration>???
<sql:transaction>??

Now only results from GdaQuery that are gda_data_model's are used.

> * for now the code depends on log4c, that dependency would have to be dropped
Sure.
For web applications I use log4c. If the extension will be in libgda,
then a GError on the output is enough.

> * the gda_value_stringify() calls can easily be replaced by other
> calls, I can help there!
It is my first code with libgda, so I just get the easy way. I will be
grateful for any help.

> * Would you agree to licence your code under the LGPL as all libgda is licenced?
Yes, no problem.

> 
> Thanks for your work,
A small idea. Real work is in libgda.

Paweł Cesar Sanjuan Szklarz.

> 
> Vivien
> 
> On 9/10/07, Paweł Cesar Sanjuan Szklarz <paweld2 gmail com> wrote:
> > Hi.
> >
> > I write a small extension to libxslt that use libgda (last version from
> > svn) to execute sql and create xml files.
> > Of course it is a prove of concept, in particular I am using functions
> > like gda_value_stringify, that are only for debug.
> >
> > The new extensions elements are:
> > node
> > <sql:query resultset="user" onempty="fault" faultcode="-1">__SQL__</>
> >  that execute a sql query and save the results on a hash.
> >
> > and functions
> > sql:getvalue('resultset_name','column_name')
> > sql:getnodeset('resultset_name')
> >
> > getvalue:
> >  gets the value of the colum 'column_name' on the first row of the data
> > model with name 'resultset_name'.
> > getnodeset:
> >  makes a nodeset for the data model with name 'resultset_name'.
> >
> > I thing that the tests on libgda can be made using a similar extension.
> > And maybe this extension can be added to libgda as a aditional feature,
> > of course after a good discution of the idea.
> >
> > My real goal is to implement Web Services with this extension.
> >
> > I put the source code on
> > http://ambargroup.pl/sqlxslt/libsqlxslt.tar.bz2
> > with the extension, a db definition for Postgres8 and a test program.
> >
> > Explication of the test program:
> >
> > The test program makes a connection to a DB from a dns, and register the
> > extension adding the conection to the XSLTTransformationContext.
> >
> > The xml data are this:
> > ------------------------------------------------
> > <?xml version="1.0" encoding="UTF-8"?>
> > <login>
> >   <login>admin</login>
> >   <password>asdasdasd</password>
> > </login>
> > ------------------------------------------------
> >
> > The xsl file:
> > ------------------------------------------------
> > <?xml version="1.0" encoding="UTF-8" ?>
> > <xsl:stylesheet version="1.0"
> >   xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
> >   xmlns:sql="http://pmsoft.ambargroup.pl/ns/sql-ext";
> >   xmlns:ae="http://ambargroup.pl/AEsession/";
> > extension-element-prefixes="sql"
> > >
> >
> > <xsl:output method="xml" indent="yes" encoding="utf-8"/>
> >
> > <xsl:variable name="login" select="/login/login/text()"/>
> > <xsl:variable name="password" select="/login/password/text()"/>
> >
> > <xsl:template match="/">
> > <!--this extension element makes a query and saves the result on a hash
> > with the name 'user'-->
> > <!--the attribute onempty and faultcode are obligatory but not used
> > now-->
> > <sql:query resultset="user" onempty="fault" faultcode="-1">
> > select * from users
> >  where
> >  login = ## /*type:gchararray name:"login"*/ AND
> >  password = ## /*type:gchararray name:"password"*/
> > </sql:query>
> > <!--here, the parameters for sql are from the xsl:variable-->
> > <xsl:variable name="userid" select="sql:getvalue('user','userid')"/>
> > <!--a new variable gets its value from the results from the sql-->
> > <ae:user>
> >   <ae:userData>
> > <xsl:call-template name="userData"/>
> >   </ae:userData>
> >   <ae:rightList>
> > <xsl:call-template name="rightList">
> >     <xsl:with-param name="userid" select="$userid"/>
> > </xsl:call-template>
> >   </ae:rightList>
> >   <ae:userTagList>
> > <xsl:call-template name="userTagList">
> >     <xsl:with-param name="userid" select="$userid"/>
> > </xsl:call-template>
> >   </ae:userTagList>
> > </ae:user>
> > </xsl:template>
> >
> > <xsl:template name="rightList">
> > <xsl:param name="userid"/>
> > <sql:query resultset="rights" faultcode="-2" onempty="ok">
> > select
> >  SR.name as name
> > from
> > users_rights as UR
> > inner join system_right as SR on (SR.rightid = UR.rightid)
> > where
> >  userid=## /*type:gint name:"userid"*/
> > </sql:query>
> > <xsl:variable name="nodeset_rights" select="sql:getnodeset('rights')"/>
> > <!--create a nodeset from the result of the sql.->
> > <ae:debug>
> > <!--debug the nodeset created be the sql extension->
> > <xsl:copy-of select="$nodeset_rights"/>
> > </ae:debug>
> > <xsl:for-each select="$nodeset_rights/row">
> >         <ae:rightSimple>
> >                 <ae:name><xsl:value-of
> > select="column[ name='name']/text()"/></ae:name>
> >         </ae:rightSimple>
> > </xsl:for-each>
> > </xsl:template>
> >
> > <xsl:template name="userData">
> >     <ae:Id><xsl:value-of
> > select="sql:getvalue('user','userid')"/></ae:Id>
> >     <ae:password><xsl:value-of
> > select="sql:getvalue('user','password')"/></ae:password>
> >     <ae:login><xsl:value-of
> > select="sql:getvalue('user','login')"/></ae:login>
> >     <ae:lastName><xsl:value-of
> > select="sql:getvalue('user','lastname')"/></ae:lastName>
> >     <ae:firstName><xsl:value-of
> > select="sql:getvalue('user','firstname')"/></ae:firstName>
> > </xsl:template>
> >
> > <xsl:template name="userTagList">
> > <xsl:param name="userid"/>
> > <sql:query resultset="tags" faultcode="-2" onempty="ok">
> > select UT.tag,UT.value,UT.userid,TT.name as type
> > from
> >  users_tags as UT
> >  inner join tag_type as TT on (UT.typeid = TT.typeid)
> >  where
> >  userid=## /*type:gint name:"userid"*/
> > </sql:query>
> > <xsl:variable name="nodeset_tags" select="sql:getnodeset('tags')"/>
> > <ae:debug>
> > <xsl:copy-of select="$nodeset_tags"/>
> > </ae:debug>
> > <xsl:for-each select="$nodeset_tags/row">
> >         <ae:userTag>
> >                 <xsl:attribute name="type">
> >                         <xsl:value-of select="column[ name='type']/text()"/>
> >                 </xsl:attribute>
> >                 <ae:tag><xsl:value-of select="column[ name='tag']/text()"/></ae:tag>
> >                 <ae:value><xsl:value-of
> > select="column[ name='value']/text()"/></ae:value>
> >         </ae:userTag>
> > </xsl:for-each>
> > </xsl:template>
> >
> > </xsl:stylesheet>
> > ------------------------------------------------
> >
> > Using the test program you get this output:
> > ------------------------------------------------
> > <?xml version="1.0" encoding="utf-8"?>
> > <!--libxslt:test element test worked-->
> > <ae:user xmlns:ae="http://ambargroup.pl/AEsession/";>
> >   <ae:userData>
> >     <ae:Id>2</ae:Id>
> >     <ae:password>asdasdasd                       </ae:password>
> >     <ae:login>admin           </ae:login>
> >     <ae:lastName>administrator</ae:lastName>
> >     <ae:firstName>admin</ae:firstName>
> >   </ae:userData>
> >   <ae:rightList>
> >     <!--libxslt:test element test worked-->
> >     <ae:debug>
> >       <resultset>
> >         <row>
> >           <column name="name">usr_create</column>
> >         </row>
> >         <row>
> >           <column name="name">usr_delete</column>
> >         </row>
> >         <row>
> >           <column name="name">adm_modul</column>
> >         </row>
> >         <row>
> >           <column name="name">adm_system</column>
> >         </row>
> >         <row>
> >           <column name="name">sys_debug</column>
> >         </row>
> >       </resultset>
> >     </ae:debug>
> >     <ae:rightSimple>
> >       <ae:name>usr_create</ae:name>
> >     </ae:rightSimple>
> >     <ae:rightSimple>
> >       <ae:name>usr_delete</ae:name>
> >     </ae:rightSimple>
> >     <ae:rightSimple>
> >       <ae:name>adm_modul</ae:name>
> >     </ae:rightSimple>
> >     <ae:rightSimple>
> >       <ae:name>adm_system</ae:name>
> >     </ae:rightSimple>
> >     <ae:rightSimple>
> >       <ae:name>sys_debug</ae:name>
> >     </ae:rightSimple>
> >   </ae:rightList>
> >   <ae:userTagList>
> >     <!--libxslt:test element test worked-->
> >     <ae:debug>
> >       <resultset>
> >         <row>
> >           <column name="tag">testtag2</column>
> >           <column name="value">testt222222</column>
> >           <column name="userid">2</column>
> >           <column name="type">system                          </column>
> >         </row>
> >         <row>
> >           <column name="tag">testtag1</column>
> >           <column name="value">testtest111111111111</column>
> >           <column name="userid">2</column>
> >           <column name="type">system                          </column>
> >         </row>
> >         <row>
> >           <column name="tag">testtag2</column>
> >           <column name="value">testt3333333332</column>
> >           <column name="userid">2</column>
> >           <column name="type">option                          </column>
> >         </row>
> >       </resultset>
> >     </ae:debug>
> >     <ae:userTag type="system                          ">
> >       <ae:tag>testtag2</ae:tag>
> >       <ae:value>testt222222</ae:value>
> >     </ae:userTag>
> >     <ae:userTag type="system                          ">
> >       <ae:tag>testtag1</ae:tag>
> >       <ae:value>testtest111111111111</ae:value>
> >     </ae:userTag>
> >     <ae:userTag type="option                          ">
> >       <ae:tag>testtag2</ae:tag>
> >       <ae:value>testt3333333332</ae:value>
> >     </ae:userTag>
> >   </ae:userTagList>
> > </ae:user>
> > ------------------------------------------------
> >
> >
> >
> > Saludos.
> > Pawel Cesar Sanjuan Szklarz.
> >
> >
> > _______________________________________________
> > gnome-db-list mailing list
> > gnome-db-list gnome org
> > http://mail.gnome.org/mailman/listinfo/gnome-db-list
> >