PHP foreach - undefined variable?

Question

I'm using Laravel 5.3's query builder, trying to add a where clause to find articles with a certain tag:

$tag_list = $request->tag_list; // tag_list is an array
if (isset($tag_list)) {
    foreach ($tag_list as $tag_id) {
        $query = $query->whereHas('tags', function ($query) {
            $query->where('id', $tag_id);
        });
    }
}

When I dump $tag_list I get...

But in the loop, I get an error:

Undefined variable: tag_id

What am I doing wrong? Any help is appreciated!

Are you sure that $tag_list is an array? If all you're getting back from a var_dump is 24 it looks like that var is a string or int. — Joe
– Joe, Commented Jan 22, 2017 at 16:25

vuliad · Accepted Answer · 2017-01-22 16:24:37Z

7

Because you are in function context. Pass tag_id variable via - use keyword

$tag_list = $request->tag_list; // tag_list is an array
if (isset($tag_list)) {
    foreach ($tag_list as $tag_id) {
        $query = $query->whereHas('tags', function ($query) use ($tag_id) {
            $query->where('id', $tag_id);
        });
    }
}

answered Jan 22, 2017 at 16:24

vuliad

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2 Comments

Jay Julian Payne Over a year ago

Ahhh I remember that now from a Laracasts tutorial... thanks @vuliad

localheinz Over a year ago

For reference, also see php.net/manual/en/functions.anonymous.php, "Example #3 Inheriting variables from the parent scope".

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