Athari
commented
8 years ago If amount of data you're working with isn't small, I'd advise to use RDBMS like MySQL. YaLinqo is supposed to be used when a database isn't avalaible or adequate, not to replace databases. You'll just lose performance, write more code and gain nothing in return.
The problem with joining is that functional syntax of LINQ supports joining only two arrays. In order to join more arrays, you'll need to create temporary arrays or objects between joins which is quite verbose and, well, annoying. In .NET, query syntax can be used, which performs all these transformations for you, but it isn't available in PHP.
You also don't need to wrap arrays in "from" if you don't perform any operations on them, YaLinqo accepts arrays as arguments in all methods.
If you don't understand how some method works, you can just look at the code, in most cases it's pretty simple. Let's look at join (it's actually one of the most complex methods). Without boilerplate, its code looks like this:
$lookup = $inner->toLookup($innerKeySelector);
foreach ($this as $ok => $ov) {
$key = $outerKeySelector($ov, $ok);
if (isset($lookup[$key]))
foreach ($lookup[$key] as $iv)
yield $resultSelectorKey($ov, $iv, $key) => $resultSelectorValue($ov, $iv, $key);
}So, it creates a lookup (array matching keys to many values), then iterates over outer sequence matching keys.
One bonus of PHP is that merging arrays is simple. So, if you have two arrays with indexes which are either unique or equal, you can use array_merge to join the results. If some keys are common, one more array can be added as an argument to "override" collapsed keys. So the general pattern is this:
$join = from($as)
->join($bs,
'$v["keya"]', '$v["keya"]',
function ($a, $b) { return array_merge($a, $b); })
->join($cs,
'$v["keyb"]', '$v["keyb"]',
function ($ab, $c) { return array_merge($ab, $c); })
->join($ds,
'$v["keyc"]', '$v["keyc"]',
function ($abc, $d) { return array_merge($abc, $d, [
'v1' => $abc['v1'],
'v2' => $d['v2'],
]); });One more reason of losing values is calling toArray instead of toList, as multiple join method calls can result in equal keys.
P. S. Not sure whether this is what you're doing — there's too much code. I hope my advice can simplify your code considerably.
anvarulugov
Hello thank you for such awesome script! I want to join 4 arrays. But honestly I coudn't undersand the documentation. Right now I have an sql query:
But I want to use yalinqo instead of mysql. I dumped all the date from these table and made php arrays. Here is the code:
The code is working, bu after second join the data of the first join is disappearing, please help me :-(