(PHP) Trouble iterating through objects

Question

Background: I am pulling in XML objects from a public IMDB-for-TV API. My goal is to pull certain values out of those objects -- like, say, a list of every episode title, put into an array so that I can do what I want with it.

Problem: Although I can write code that does execute exactly the way I want it, it spits out errors as it does so, so I know something's wrong with the way I iterate over my objects... but I can't figure out a better way. I'd really love some advice.

So first off, here's a look at the object I'm dealing with.

SimpleXMLElement Object
(
    [Episodelist] => SimpleXMLElement Object
        (
            [Season] => Array
                (
                    [0] => SimpleXMLElement Object
                        (
                            [episode] => Array
                                (
                                    [0] => SimpleXMLElement Object
                                        (
                                            [epnum] => 1
                                            [seasonnum] => 01
                                            [prodnum] => 101
                                            [airdate] => 1989-07-05
                                            [link] => http://www.tvrage.com/Seinfeld/episodes/305788
                                            [title] => Good News, Bad News
                                        )

                                    [1] => SimpleXMLElement Object
                                        (
                                            [epnum] => 2
                                            [seasonnum] => 02
                                            [prodnum] => 103
                                            [airdate] => 1990-05-31
                                            [link] => http://www.tvrage.com/Seinfeld/episodes/150618
                                            [title] => The Stakeout
                                        )

The show is an object containing an object "episode list", which contains object "season x", which contains object "episode y", which contains the value I'm after -- "title". So for each episode, I want to grab $this->list->Season[X]->episode[Y]->title.

Here is the function I wrote to do this. It takes two arguments: the season number, and the episode number.

 public function showEpisode($s,$e) {
    $s = $s - 1; // To compensate for zero-indexing.
    $e = $e - 1; 
    if (!empty($this->list->Season[$s]) && !empty($this->list->Season[$s]->episode[$e])) {
        return $this->list->Season[$s]->episode[$e]->title;     
    } else {
        return 0;
    }

}

I know there's something wrong with how it's written.

Anyway, here's my code for actually working with it.

 $season = 1;
 $episode = 1;
 $errors = 0;
 while ($errors < 2) {
if ($xfiles->showEpisode($season,$episode)!= 0) {
    echo $xfiles->showEpisode($season,$episode) . "<br />"; 
    $episode++;
    $errors = 0;
} else {
    $errors++;
    $season++;
    $episode = 1;
}
 }

My logic is:

Start at Season 1, Episode 1.
Echo the title of the current episode.
If that fails, increment the error-counter by one, and go up a season by incrementing $season++ and putting the $episode counter back at 1.
If you get two errors in a row, it means going up a season failed, because we've hit the end of the show, so the loop ends.

Desired result: A neat, simple list of every episode title. Actual result: A blank page, using this code; nothing is ever returned. When I used my last version of the function, which I have very stupidly deleted and cannot seem to recreate, I did echo a full set of episodes exactly as I wanted -- but after each season, and three times at the end of the file, I got "Trying to get property of non-object" errors, because of the calls to non-existent episodes.

Question: What is the correct, practical way to loop through a large object like this? What conditions should I use in my showEpisode function to check if the result will exist or not?

Thanks a ton to anyone who can help, I've done my best and Googled a lot but I'm just baffled.

+1, this is the best-written question I have ever seen! I'm really glad I could help :) — scenia
– scenia, Commented Jan 29, 2014 at 14:12

scenia · Accepted Answer · 2014-01-29 13:56:22Z

2

This looks like a job for a foreach-loop.

foreach ($xfiles->list->Season as $season) {
    foreach ($season->episode as $episode) {
        echo $episode->title . "<br />"; 
    }
}

Alternatively (or should I say ideally), put this inside a method of the list object and replace $xfiles with $this.

answered Jan 29, 2014 at 13:56

scenia

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1 Comment

GreenTriangle Over a year ago

Well... damn. That works absolutely perfectly. Such a simple and elegant solution, I never thought of doing something like that. Thanks a ton, I appreciate the advice and I actually learnt something from it!

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