Re: dereferencing issues

Thanks..

I managed to figure it out but yor mail was very instructional.

What I did was as follows
..some code...

$rows = $sth->fetchall_arrayref({});

my @AoH = @$rows;
for my $p (0..$#AoH) {

                         for my $bulle ( keys %{ $AoH[$p] } ) {

                                                                 if  
(($AoH[$p]{$bulle}) =~ m/^[\d]+-[\d]+$/) {


                                                                         
                  my @fields = split /-/, ($AoH[$p]{$bulle});
                                                                         
                  my $nr1 = "-";
                                                                         
                  my $nr2 = "-";
                                                                         
                  $rows->[$p]->{Mobil} = $nr1.$fields[0].$fields[1]. 
$nr2;
                                                                         
                  }
        }
}


Its probably not elegant but it gives me a chance to change the value  
of row "Mobil" before feeding it to the template. In this particular  
example it doesn do anything useful I was simply doing it to learn.

Your input was greatly appreciated and if you see me missing  
something obvious the give me a "holler". And thanks for the dumper  
idea..did really know about that.

Thomas


12 aug 2005 kl. 16.06 skrev Ragan, Steve:

>
> To understand how to de-ref you must understand what it is you're  
> trying to de-ref.
>
> Lets assume you have a simple SQL query like this that returns  
> first and last names from a table -
>
>     my $sql = qq[
>     SELECT first, last
>       FROM persons
>     ];
>
> First you prepare and execute -
>
>     my $sth = $dbh->prepare($sql) || die("Unable to prepare  
> statement");
>
>     $sth->execute() || die("Database execute Error: $DBI::errstr");
>
> then fetch the results. If you use the regular fetchall_arrayref(),  
> you're getting an arrarref of arrayref structure.
> That is a reference to array of rows that itself is a reference to  
> array of columns.
> To help visualize the structure you can use the Data::Dumper module
>
>     use Data::Dumper;
>
>     my $ra_results = $sth->fetchall_arrayref();
>
>     my $d = Data::Dumper->new([$ra_results], [qw(ra_results )] );
>
>
>     print '<pre>' . $d->Dump . '</pre>';   # if you in HTML,  
> otherwise just print $d->Dump
>
>
> The structure would appear something like this -
>
> $ra_results = [
>                 [
>                   'Duane',
>                   'Allman'
>                 ],
>                 [
>                   'Stevie Ray',
>                   'Vaughn'
>                 ]
>               ];
>
>
> You could access specific rows and columns directly -
>
>   First row -
>
>     my $first_name = $ra_results->[0][0];
>     my $last_name  = $ra_results->[0][1];
>
> or loop through all rows accessing each column -
>
>     for my $ra_row (@{$ra_results}) {
>         my $first_name = $ra_row->[0];
>           my $last_name  = $ra_row->[1];
>           ...( more code here ) ...
>     }
>
>
>
>
> If you fetch using $sth->fetchall_arrayref({}), you're getting an  
> arrarref of hashref structure.
> That is a reference to array of rows that itself is a reference to  
> a hash of column name/column values.
> If you use Data::Dumper again you'll see the structure looks like this
>
> $ra_results = [
>                 {
>                   'last' => 'Allman',
>                   'first' => 'Duane'
>                 },
>                 {
>                   'last' => 'Vaughn',
>                   'first' => 'Stevie Ray'
>                 },
>               ];
>
>
> You would loop through that structure like this -
>
>     my $ra_results = $sth->fetchall_arrayref({});
>
>     for my $ra_row (@{$ra_results}) {
>         for my $key (keys %{$ra_row}) {
>             my $value = $ra_row->{$key};
>            ...( more code here ) ...
>         }
>     }
>
>
> If you're using TMPL_LOOP's you probably don't need to be munging  
> around with that data structure anyway since you need to assign an  
> arraryref of hasref to the param -
>
>    $template->param(EMPLOYEE_INFO => $ra_results );
>
>
> Check out the perl doc perldsc (Data Structures Cookbook) for a  
> discussion on data structures and derefernencing.
>
> Good luck
> Steve
> (Programmer, not soda jerk :)
>
>
> Steve Ragan
> Sr. Internet Developer
> Harris Connect
> 2500 Westchester Ave.
> Purchase, NY 10577
> T 914.641.3948
> F 914.641.3584
> [email protected]
> www.harrisconnect.com
>
>
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of
> Thomas Nyman
> Sent: Friday, August 12, 2005 5:11 AM
> To: [email protected]
> Subject: [htmltmpl] dereferencing issues
>
>
> Hi
>
> I've tried studying perldoc pages, the htmps template pages and most
> things relating to dbi etc.
>
> Despite this I have been unable to understand how to dereference
> fetchall_arrayref({})
>
> I can dereference fetchall_arrayref()  but not  fetchall_arrayref
> ( {} ), i.e the arrayref of hash refs.
>
> I would like to query the database using fetchall_arrayref({}), the
> dereference that and perhaps make changes to some values, put it back
> into  an arrayref({}) and then dump it to html template.
>
> SO far I'm stumped with the first part..i simply cant dereference the
> *fg!?*-thing  <grinning> .. anyway, please is there some who can help
> iterate through arrayref({}) (both key and value).
>
> AN example
>
> I query the database for "Name", "Adress", "Phone", "Fax", "Email"
>
> the $rows = $sth->fetchall_arrayref({});
>
> now i would like to dump my rows into an array and check for certain
> values etc, for instance lets say the phonenumber is represented as
> 512445566 in the database, but i want it to display as 512-445566 in
> the html-template..therefore i would need to access the "Phone"
> query, check its format, possibly change it, insert the new value in
> my arrayref of hashrefs.
>
> (on my knees and waiting)
>
> Thomas
>
>
>
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September 19-22, 2005 * San Francisco, CA * Development Lifecycle Practices
Agile & Plan-Driven Development * Managing Projects & Teams * Testing & QA
Security * Process Improvement & Measurement * http://www.sqe.com/bsce5sf