YouTube API v3 get last video in playlist - php

Question

Some basic background: I help run a gaming channel on YouTube, and I'm building a utility (using PHP) to integrate the channel's content with a companion website. Our playlists are primarily "let's play" series ordered by publication date that follow chronological progress through various games, and I would like the website to display the "latest episode" from a select number of series.
I know that I can work my way to the last video by chaining calls to the following:
$youtubeService->playlistItems->listPlaylistItems(
"snippet",
array(
"playlistId" => $playlistId
"pageToken" => $nextPageToken
)
)
And simply grab the last item in the response set when $nextPageToken is unset.
However, this strikes me as incredibly inefficient--partly because I believe it eats away at my API request quota, but mostly because it's going to slow down the overall response time of the site. Neither of those are ideal.
It seems like there should be an easier way to grab the "latest" video in a playlist either by changing the order of the response, or with some handy function, but I can't find any documentation on it.
I've looked at using the Search functions over the PlaylistItems, but (according to the documentation), Search only accepts Channel IDs as a parameter and not Playlist IDs, which makes me think that its the wrong direction to head.

Answer 1

The short answer here is that this appears to be impossible under the current version of the API. There is no apparent way to essentially select videos in reverse, but I did make a minor change which resulted in whole process being a tad more efficient.
This is the original code:
$items = $youtube->playlistItems->listPlaylistItems(
"snippet",
array(
"playlistId" => $playlistId,
"maxResults" => 50
)
);
while ($items->nextPageToken) {
$items = $youtube->playlistItems->listPlaylistItems(
"snippet",
array(
"playlistId" => $playlistId,
"maxResults" => 50,
"pageToken" => $items->nextPageToken
)
);
}
if ($items) {
return end($items->getItems());
}
This is the fix:
First, I added an object to assist with caching:
class PlaylistCache {
protected $expirationDate;
protected $playlistId;
protected $latestEpisode;
__construct($playlistId, $latestEpisode) {
$this-playlistId = $playlistId;
$this->latestEpisode = $latestEpisode;
$this->expirationDate = time() + 86400;
// get current time + 24 hours
}
public function getLatestEpisode() {
return $this->latestEpisode;
}
public function getPlaylistId() {
return $this->playlistId;
}
public function isExpired() {
return $this->expirationDate < time();
}
}
Then, before polling the API, I look to see if I have a cached version available, and I only resort to the API if that cached version is expired.
$playlistCache = json_decode(get_option('playlist_cache_' . $playlistId));
if ($playlistCache->isExpired()) {
$items = $youtube->playlistItems->listPlaylistItems(
"id",
array(
"playlistId" => $playlistId,
"maxResults" => 50
)
);
while ($items->nextPageToken) {
$items = $youtube->playlistItems->listPlaylistItems(
"id",
array(
"playlistId" => $playlistId,
"maxResults" => 50,
"pageToken" => $items->nextPageToken
)
);
}
if ($items) {
$videoId = end($items->getItems()[0]->getId());
$video = $youtube->videos->listVideos("snippet", array('id' => $videoId))
$video = $video->getItems()[0];
$playlistCache = new PlaylistCache($playlistId, $video);
update_option('playlist_cache_' . $playlistId, json_encode($playlistCache)));
}
}
return $playlistCache->getLatestEpisode();
The other big change here is that my calls to listPlaylistItems() are requesting the id instead of the snippet.
According to the documentation, the snippet costs 2 units of the API quota while requests for the id are 0. So, I don't need to snag the snippet for every single item on every single page. I only need to grab the snippet of the final video in the results, which I can do with the more refined call to
$youtube->videos->listVideos()
With the addition of the PlaylistCache class I only reach out to the API when the cached version of the Playlist returns true on the $playlistCache->isExpired() call, so I only need to poll the entire playlist one time every 24 hours instead of 1 time every page load for every user.
It's still not exactly ideal, but as far as I can tell, it's the best option available right now.

Answer 2

Firstly, you need to get the channelId for the user via HTTP request:
Sample request:
https://www.googleapis.com/youtube/v3/channels?part=snippet&forUsername={0}&key={1}
where {0} is the USERNAME and key is you API key
Then, get the list of videos by calling 'PlaylistItems:list', it returns a collection of playlist items that match the API request parameters. You can retrieve all of the playlist items in a specified playlist or retrieve one or more playlist items by their unique IDs.
Sample request:
https://www.googleapis.com/youtube/v3/search?order=date&part=snippet&channelId={0}&key={1}
From there, you can create an array to get the last video in the playlist. Include max-results parameter, the max-results specifies the maximum number of results that included in the result set.

Answer 3

Typically, the latest video in a playlist in added to the front, not the end.