2

Trips hasMany Legs

Airports has no associations

How can I find the cheapest trip for each destination airport using CakePHP?

Right now, the only thing I can think of to do is to foreach through an array of airports. This would require hundreds of queries to the database (which I think is not the fastest way of doing it). 

function getCheapestTrip($origin){

$airports=$this->Airport->getAirports();
foreach($airports as $airport):
$cheapest_flights=$this->Trip->find('first', 
array(
'conditions'=>array('Leg.origin'=>$origin, 'MIN(Trip.price) as price'),
'fields'=>array('Trip.origin','price','Leg.destination','Leg.depart','Leg.arrive'),
'recursive'=>2,
));
 endforeach;
}
}

Also, I think that this data type stuff should be in the model per CakePHP conventions (Fat models, skinny controllers). I read that to call a different model's function such as getAirports I can use loadModel but I found that in CakePHP's controller method section. How should one get another model's data/model function into anothers?

Thanks!

JohnAllen
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  • In the code you've provided, you're looping through $airports, but are not using $airport anywhere. You're executing the same query over and over. Are you missing a condition? – RabidFire Dec 01 '10 at 02:38
  • Yeah, the code I posted is definitely just a starting point and earlier I was exhausted when I posted it. I'm going to try and figure this thing out again and maybe post/edit something else if I can't get it. Thanks for commenting. – JohnAllen Dec 01 '10 at 02:49

3 Answers3

0

If you're looking for a better algorithm rigth now I do not have the solution.

Mine is a design solution: basically you should add a field to your destination airport which will be updated every time you add a new flight so you have your information directly in your destination record.

This stands if I have understood your problem. I'm not english so I'm not familiar with the semantic of "leg" associated to a trip (to me it's a body part)

dierre
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0

The problem you're solving is the Traveling Salesman Problem: http://en.wikipedia.org/wiki/Travelling_salesman_problem

From what I've read on how google maps does it, you'll want to precompute your most common routes and connections. Keep that precomputed info in a cheap cache (memcache prolly). Basically, you won't be able to recalculate each time, so calc a few common ones and build a precomputed cache.

WRT the algorithm, some google searching will be your friend for tips and tricks. This problem has been solved many times (none are exactly computationally efficient, which is why you should precompute and cache).

Travis Leleu
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  • I'm actually just trying to find unique destinations. Like find just the cheapest flight to each possible destination from that origin_airport. I explained the problem poorly; partly because it was a difficult one for me. – JohnAllen Dec 02 '10 at 21:03
0

The answer to your second question, "How to load a model within another model?" can be found here.

Community
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RabidFire
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