Only print array row data if id is found in a whitelist array [duplicate]

Question

I have a list of categories for my videos, and with this simple foreach loop, I'm displaying all of them inside hyperlinks.

Now, what I want to do is display only some of them, based on the category ID.

Code that display all the categories:

$idx = 0;

foreach ($this->categories as $category) 
{
    echo "\n" . ($idx++ ? '| ' : '') . '<a href="' . KM_Helpers::getCategoryURL($category) . '">' . $category['name'] . '</a>';
}

Let's say now I want to display only the categories with the ids: 2,8,21,22. I can use $category['id'] to get the IDS.

I was thinking of having an array that contains only the ID I want to show...

$myarray = array(2, 8, 21, 22);

My question is, how can I loop in my $category array, displaying only the ID contained in the array? (Based on $category['id'] )

@Jleagle no. the first time it will return false. $idx++ returns the value of $idx before incrementing it. — Mark Reed
– Mark Reed, Commented Apr 26, 2012 at 14:22
All of the answers above are assuming that you are pulling the ID into the categories query. Are you doing that? @Surreal Dreams, I read the $category['id'] line more of a question not a statement. — Ryan B
– Ryan B, Commented Apr 26, 2012 at 14:25

Mark Reed · Accepted Answer · 2012-04-26 14:25:57Z

2

If the id value matches the index in the categories array, you can just loop over the ones you want:

foreach ($myarray as $id)
{
  $category = $this->categories[$id];
  echo "\n".($idx++ ? '| ' : '') .
    '<a href="' . KM_Helpers::getCategoryURL($category) . '">' .
     $category['name'] . '</a>';
}

Otherwise, you have to do a double-loop (possibly hidden by in_array), either to check if an id is valid or to find the category with a given valid id.

edited Apr 26, 2012 at 14:25

answered Apr 26, 2012 at 14:14

Mark Reed

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1 Comment

Surreal Dreams Over a year ago

This is a slick way to approach the problem - iterate over the approved ids instead of iterating over the categories - less overhead. OP never mentions doing anything else that requires touching all the categories each time, so +1.

John Conde · Accepted Answer · 2012-04-26 14:14:33Z

1

$idx = 0;
$myarray = array(2, 8, 21, 22);
foreach($this->categories as $category) 
{
    if (!in_array($category['id'], $myarray)) {
        continue; // skip it if the id isn't in your array of accceptable IDs
    }
    echo "\n".($idx++ ? '| ' : '').'<a href="'.KM_Helpers::getCategoryURL($category).'">'.$category['name'].'</a>';
}

answered Apr 26, 2012 at 14:14

John Conde

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Comments

Surreal Dreams · Accepted Answer · 2012-04-26 14:16:25Z

1

Not a problem. Add in some simple logic to test if the id is on your list of "approved" ids:

$idx = 0;
$myarray = array(2, 8, 21, 22);

foreach($this->categories as $category) 
{
    if(in_array($category['id'], $myarray)
    {
        echo "\n".($idx++ ? '| ' : '').'<a href="'.KM_Helpers::getCategoryURL($category).'">'.$category['name'].'</a>';
    }
}

This tests the $category['id'] in each iteration of the loop and if it's in your array of ids, you echo the link. Otherwise the category item is ignored and the loop moves on.

answered Apr 26, 2012 at 14:16

Surreal Dreams

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Comments

472084 · Accepted Answer · 2012-04-26 14:21:50Z

1

$ids= array(2, 8, 21, 22);

$idx = 0;
foreach($this->categories as $id => $category){
    if (in_array($category['id'] , $ids)) {
        echo "\n".($idx++ ? '| ' : '').'<a href="'.KM_Helpers::getCategoryURL($category).'">'.$category['name'].'</a>';
    }
}

edited Apr 26, 2012 at 14:21

answered Apr 26, 2012 at 14:15

472084

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