Question

I’ve got a “steps” table, with the “id” and the text of the step named “step”. Then I have a “customers” table with “id” and other customer info. Finally, I have a “customers_steps” join table with “customer_id” and “step_id”. The goal is to have a list of steps, and show which ones were completed. But I’m stuck…

To make sure I’m not missing anything, in the “customer” model, I have

var $has_many = array ('step');

In the “step” model, I have

var $has_many = array('customer');

Right now, I’m looping the steps, then looping through the customer’s steps to see if they match… but it’s a lot of code, and I KNOW there has to be a faster way, and I’m just missing it:

$c = new Customer();
$c->get_by_id(1);
$c->step->get();
$s = new Step();
$s->get();
foreach($s as $step) 
{
   foreach($c as $customer) 
   {
      if($customer->step->id == $step->id)
      {
         $match = true;
      }
   }
   if($match)
   {
     echo "match - " . $step->step;
   } 
   else 
   {
     echo $step->step;
   }
}

This works… but what can I do to make it better? Thanks in advance.

Answer 1

You have a many-to-many relationship, so you’ll never be able to do this in one go.

Ideally, you need a LEFT JOIN between steps and customers_steps, which would produce a resultset with all steps in it, and a NULL value for those steps not present for a specific customer id. But since Datamapper is about relationships, it can’t report relations that aren’t there.

You could use

// get the customer and his steps
$c = new Customer(1);
$c->step->get();

// create the list of assigned step id's
$list = array();
foreach ($c->step as $step)
{
    $list[] = $step->id;
}

// get the steps not assigned
$s = new Step();
$s->where_not_in('id', $list);

// at this point $c->steps contains all matching steps
// and $s all steps that don't match
print_r($c->steps->all_to_array());
print_r($s->all_to_array());