If array isset, do something?

Question

I am posting multiple checkboxes, and putting them into an array - for example: "tags[]"

When posting them, I am imploding them with commas.

If NO tags are checked on the form, and then posted, I get errors as the script is trying to implode something that isn't there.

I have tried using something like this:

if (isset($_POST['tags'])){ 
    $tags = implode(", ", noescape($_POST['tags'])); 
}  

What is the best way to check if it exists, then implode it?

isset, array_key_exists?

Answer 1

You could do it in one line, in this situation isset and array_key_exist would give you the same result but then you may want to check if $_POST['tags'] is an array...

$tags = isset($_POST['tags']) ? implode(", ", noescape($_POST['tags'])) : null;

or

$tags = (isset($_POST['tags']) && is_array($_POST['tags'])) ? implode(", ", noescape($_POST['tags'])) : null;

You can test here : http://codepad.org/XoU4AdsJ

Answer 2

That should work:

if (isset($_POST['tags']) && is_array($_POST['tags'])){ 
    $tags = implode(", ", noescape($_POST['tags'])); 
}  

Answer 3

if(array_key_exists('tags',$_POST))
{
..................
}

Answer 4

if (!empty($_POST['tags'])) {
   $tags = implode(", ", noescape($_POST['tags']));
}

Answer 5

I would just use is_array before imploding so your implode only works if your imploded var is an existing array. Returns 0 if it is not set as well :)

http://php.net/manual/en/function.is-array.php

Answer 6

Actually, an easier way to do this would be to do something like this:

<input type="hidden" name="tags[]" value="none" />
<input type="checkbox" name="tags[]" value="Tag 1" />
<input type="checkbox" name="tags[]" value="Tag 2" />
<input type="checkbox" name="tags[]" value="Tag 3" />

And then remove the default value.

Obviously this would still cause errors if some malicious user decided to send a post to your script without any data at all.

Answer 7

I'd use is_array() and count():

if (is_array($_POST['tags']) && count($_POST['tags'])>0){ 
    $tags = implode(", ", noescape($_POST['tags'])); 
}