Editing IRStats Technical Documentation (section)

== View ==
A view processes the stats data filtered by the parameters and creates a visualisation.  It is intended that savvy users create their own views.

=== Functions ===
All views inherit:
*new(params_obj, database_interface_object) - returns the object.
*render - calls populate, then returns whatever the visualisation renders
All visualisations must implement:
*new - passes arguments to superclass, then calls 'initialise'.
*initialise - the Configuration Constants are set here.
*populate - The engine that powers IRStats.

=== View::DownloadCountHTML ===
The DownloadCountHTML is an extremely simple view.  It retrieves one row from the database and does no processing, making it ideal for a quick walkthrough:

==== Housekeeping ====
At the top of the file, we need:
 package IRStats::View::DownloadCountHTML;
 use strict;
 use warnings;
Now, which modules will we use.  I've included perchardir, the graph making package, even though we're not using it.
 use IRStats::DatabaseInterface;
 use IRStats::Cache;
 use IRStats::Visualisation::HTML;
 use IRStats::View;
 use perlchartdir;
And link to superclass. 
 our @ISA = qw/ IRStats::View /;

==== Configuration Constants ====
We aren't actually interested in any columns, just in the count, but we put that in the columns array anyway.
We also create our visualisation here.
 sub initialise
 {
        my ($self) = @_;
        $self->{'sql_params'} = {columns => [ 'COUNT' ]};
        $self->{'visualisation'} = IRStats::Visualisation::HTML->new();
 }

==== new ====
The new function shouldn't ever need to be any different from this:
 sub new
 {
        my( $class, $params, $database ) = @_;
        my $self = $class->SUPER::new($params, $database);;
        $self->initialise();
        return $self;
 }

==== populate ====
Almost every populate function should start by checking the cache.

 sub populate
 {
    my ($self) = @_;
    my $cache = IRStats::Cache->new($self->{'params'}->get('id'));
    if ($cache->exists)
    {
        $self->{'visualisation'} = $cache->read();
        return;
    }
Next, we have to retreive from the database:

    my $query = $self->{'database'}->get_stats(
            $self->{'params'},
            $self->{'sql_params'}
            );
Now we process them.  In this case, we don't even need a loop as we know there's only going to be one row.  We'll stick the result straight into some html, and save it.  Don't forget that if there isn't any data, you still have to output something.
    my @row = $query->fetchrow_array();
    my $html = '<span class="irstats_view_fulltextcounthtml">' . ($row[1] ? $row[1] : '0') . "</span>";
A little housekeeping:
    $query->finish();
Pop the data into the visualisation:
    $self->{'visualisation'}->set('html',$html);
Finally, we should write to the cache so we don't have to query the database next time.
    $cache->write($self->{'visualisation'});
 }

And that's a really simple view.

=== Using Periods ===

If we wanted to break our daterange into periods, we'd need to do something like this:

 my $periods = IRStats::Periods->new($self->{'params'}->{'start_date'},$self->{'params'}->{'end_date'});
 foreach my $period ( @{$periods->calandar_months()} )
 {
    $self->{'params'}->mask($period);
    my $query = $self->{'database'}->get_stats(
            $self->{'params'},
            $self->{'sql_params'}
    );
    $self->{'params'}->unmask();
    #process and put into variables
 }