NAME

XML::Generator::DBI - Generate SAX events from SQL queries

SYNOPSIS

  use XML::Generator::DBI;
  use XML::SAX::Writer;
  use DBI;
  my $dbh = DBI->connect("dbi:Pg:dbname=foo", "user", "pass");
  my $sth = $dbh->prepare("select * from mytable where mycol = ?");
  my $generator = XML::Generator::DBI->new(
                        Handler => XML::SAX::Writer->new(),
                        );
  $generator->execute($sth, $mycol_value);

DESCRIPTION

This module generates SAX events from SQL queries against a DBI connection.

The default XML structure created is as follows:

  <database>
   <select>
    <row>
     <column1>1</column1>
     <column2>fubar</column2>
    </row>
    <row>
     <column1>2</column1>
     <column2>intravert</column2>
    </row>
   </select>
  </database>

Alternatively, pass the option AsAttributes => 1 to either the execute() method, or to the new() method, and your XML will look like:

  <database>
    <select>
      <row column1="1" column2="fubar"/>
      <row column1="2" column2="intravert"/>
    </select>
  </database>

Note that with attributes, ordering of columns is likely to be lost, but on the flip side, it may save you some bytes.

Nulls are handled by excluding either the attribute or the tag.

API

XML::Generator::DBI->new()

Create a new XML generator.

Parameters are passed as key/value pairs:

Handler (required)

A SAX handler to recieve the events.

dbh (required)

A DBI handle on which to execute the queries. Must support the prepare, execute, fetch model of execution, and also support type_info if you wish to use the ShowColumns option (see below).

AsAttributes

The default is to output everything as elements. If you wish to use attributes instead (perhaps to save some bytes), you can specify the AsAttributes option with a true value.

RootElement

You can specify the root element name by passing the parameter RootElement => "myelement". The default root element name is "database".

QueryElement

You can specify the query element name by passing the parameter QueryElement => "thequery". The default is "select".

RowElement

You can specify the row element name by passing the parameter RowElement => "item". The default is "row".

Indent

By default this module does no indenting (which is different from the previous version). If you want the XML beautified, pass the Indent option with a true value.

ShowColumns

If you wish to add information about the columns to your output, specify the ShowColumns option with a true value. This will then show things like the name and data type of the column, whether the column is NULLABLE, the precision and scale, and also the size of the column. All of this information is from $dbh->type_info() (see perldoc DBI), and may change as I'm not 100% happy with the output.

ByColumnName

It allows usage of column names (aliases) for element generation. Aliases can contain slashes in order to generate child elements. It is limited by the length of aliases - depends on your DBMS

Example:

 $select = qq(
    SELECT  c.client as 'client_id',
            c.company_name as 'company_name',
            c.address_line as 'address/address_line',
            c.city as 'address/city',
            c.county as 'address/county',
            c.post_code as 'address/post_code',
            co.name as 'address/country',
            c.phone as 'phone',
            c.fax as 'fax',
            c.payment_term as 'payment_term',
            c.accounting_id as 'accounting_id'

    FROM    client c,
            country co

    WHERE   c.country = co.country
    AND     c.client = $client_id
            );

 $gen->execute( 
                     $select,
                     undef,
                     ByColumnName => 1,
                     RootElement => 'client_detail',
                     RowElement => 'client',
                     QueryElement => undef
                        );

 print $output;

 <?xml version="1.0" encoding="UTF-8"?>
 <client_detail>
   <client>
     <client_id>3</client_id>
     <company_name>SomeCompanyName</company_name>
     <address>
       <address_line>SomeAddress</address_line>
       <city>SomeCity</city>
       <county>SomeCounty</county>
       <post_code>SomePostCode</post_code>
       <country>SomeCountry</country>
     </address>
     <phone>22222</phone>
     <fax>11111</fax>
     <payment_term>14</payment_term>
     <accounting_id>351</accounting_id>
   </client>
 </client_detail>

GroupBy

By this parameter you can group rows based on changes in the value of a particular column. It relys on ordering done by your SQL query. This parameter requires two more parameters:

GroupElement - the name of element holding all 'row' elements.
GroupAttribute: or
GroupValueElement: GroupAttribute - when the 'value' goes as attribute of GroupElement. GroupAttribute is the name of this attribute.
GroupValueElement - when the 'value' goes in a separate element. GroupValueElement is the name of the element holding 'value'.

Note that in order to avoid unwanted nesting RowElement is undef.

Example:

 contractor_job time_record 
 -------------- ----------- 
              9          10 
              9          13 
              9          14 
             10           9 
             10          11 
             10          12 

 $select = qq(
    SELECT  time_record,
            contractor_job

    FROM    time_record

    ORDER BY contractor_job
            );

Using GroupAttribute:

 $gen->execute(
                     $select, 
                     undef, 
                     ByColumnName => 1,
                     RootElement => 'client_detail',
                     RowElement => undef,
                     GroupBy => 'contractor_job',
                     GroupElement => 'group',
                     GroupAttribute => 'ID',
                     QueryElement => undef
                        );

 print $output;

 <?xml version="1.0" encoding="UTF-8"?>
 <client_detail>
   <group ID="9">
     <time_record>10</time_record>
     <time_record>13</time_record>
     <time_record>14</time_record>
   </group>
   <group ID="10">
     <time_record>9</time_record>
     <time_record>11</time_record>
     <time_record>12</time_record>
   </group>
 </client_detail>

Using GroupValueElement:

 $gen->execute(
                     $select, 
                     undef, 
                     ByColumnName => 1,
                     RootElement => 'client_detail',
                     RowElement => undef,
                     GroupBy => 'contractor_job',
                     GroupElement => 'group',
                     GroupValueElement => 'ID',
                     QueryElement => undef
                        );

 print $output;

 <?xml version="1.0" encoding="UTF-8"?>
 <client_detail>
   <group>
     <ID>9</ID>
     <time_record>10</time_record>
     <time_record>13</time_record>
     <time_record>14</time_record>
   </group>
   <group>
     <ID>10</ID>
     <time_record>9</time_record>
     <time_record>11</time_record>
     <time_record>12</time_record>
   </group>
 </client_detail>

$generator->execute($query, $bind, %params)

You execute a query and generate results with the execute method.

The first parameter is a string containing the query. The second is a single or set of bind parameters. If you wish to make it more than one bind parameter, it must be passed as an array reference:

    $generator->execute(
        "SELECT * FROM Users WHERE name = ?
         AND password = ?",
         [ $name, $password ],
         );

Following the bind parameters you may pass any options you wish to use to override the above options to new(). Thus allowing you to turn on and off certain options on a per-query basis.

$generator->execute_one($query, $bind, %params)

If you wish to execute multiple statements within one XML structure, you can use the "execute_one()" method, as follows:

  $generator->pre_execute();
  $generator->execute_one($query);
  $generator->execute_one($query);
  $generator->post_execute();

The pre and post calls are required.

Other Information

Binary data is encoded using Base64. If you are using AsElements, the element containing binary data will have an attribute dbi:encoding="base64", where the DBI namespace is bound to the URL "http://axkit.org/NS/xml-generator-dbi". We detect binary data as anything containing characters outside of the XML UTF-8 allowed character set.

AUTHOR

Matt Sergeant, matt@sergeant.org

LICENSE

This is free software, you may use it and distribute it under the same terms as Perl itself. Specifically this is the Artistic License, or the GNU GPL Version 2.