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Add http:// prefix to URL when missing

Posted by: admin November 30, 2021 Leave a comment

Questions:

Hello I have a very simple code

<a href="'.$aProfileInfo['Website'].'" target="_self">
    <div class="callButton">Website</div>
</a>

The problem is that if the user does not enter http:// the link will then point to my website and not to the external website as it should.

How do I check in PHP if the user has not entered http:// and automatically add it when it is not there?

Answers:

I think you’d better use the built in function parse_url() which returns an associative array with its components

something like this will work for you:

 if  ( $ret = parse_url($url) ) {

      if ( !isset($ret["scheme"]) )
       {
       $url = "http://{$url}";
       }
}

###

I personally use this, which is partially taken from php docs

$scheme = parse_url($link, PHP_URL_SCHEME);
if (empty($scheme)) {
    $link = 'http://' . ltrim($link, '/');
}

###

A simple solution which may not work in all cases (i.e. ‘https://’):

if (strpos($aProfileInfo['Website'],'http://') === false){
    $aProfileInfo['Website'] = 'http://'.$aProfileInfo['Website'];
}

###

There are two ways of tackling this problem: url parsing and regular expressions.

Some will say url parsing is right, but regular expressions work just as well in this case. I like being able to have simple one-liners for things like this especially because this would be a common occurrence in template files where you may need a one-liner inside an echo statement to maintain readability.

Regular Expressions

We can do this in a single function call with preg_replace.

preg_replace('/^(?!https?:\/\/)/', 'http://', $aProfileInfo['Website'])

This uses a negative lookahead at the beginning of the string that looks for http:// or https://. If either are found, the replace doesn’t happen. If they aren’t found, it replaces the beginning of the string (0 characters) with http:// essentially prepending this to the string without modifying it.

In context:

<a href="'. preg_replace('/^(?!https?:\/\/)/', 'http://', $aProfileInfo['Website']).'" target="_self">
    <div class="callButton">Website</div>
</a>

URL Parsing

(parse_url($aProfileInfo['Website'], PHP_URL_SCHEME) ? '' : 'http://') . $aProfileInfo['Website']

What this does is find out if a scheme is present on the link throught parse_url($aProfileInfo['Website'], PHP_URL_SCHEME). Then using a ternary operator, it will either output '' if there was one found or 'http://' if one wasn’t found. Then it appends the link onto that.

In context:

<a href="'.((parse_url($aProfileInfo['Website'], PHP_URL_SCHEME) ? '' : 'http://') . $aProfileInfo['Website']).'" target="_self">
    <div class="callButton">Website</div>
</a>

###

You could use strpos:

// Trim trailing whitespace
$aProfileInfo['Website'] = trim($aProfileInfo['Website']);

// Test if the string begins with "http://"
if (strpos($aProfileInfo['Website'], 'http://') !== 0) {
  $aProfileInfo['Website'] = 'http://' . $aProfileInfo['Website'];
}

###

You can use this function as a general if nothing from the array is found in the string append something to it.

function httpify($link, $append = 'http://', $allowed = array('http://', 'https://')){

  $found = false;
  foreach($allowed as $protocol)
    if(strpos($link, $protocol) !== 0)
      $found = true;

  if($found)
    return $link;
  return $append.$link;
}

###

You also may take into account that “http(s)” must be at the beginning of the url:

if (preg_match('/^https?:\/\//', $aProfileInfo['Website']) === 0) {
    $aProfileInfo['Website'] = 'http://'.$aProfileInfo['Website'];
}

###

Something like this?

if (!strpos($aProfileInfo['Website'], 'http://')) {
    $aProfileInfo['Website'] = 'http://' . $aProfileInfo['Website'];
}

###

Here is another example with string subtraction:

$changeLink = $myRow->site_url;
  if(substr($changeLink, 0, 7) != 'http://') {
     $changeLink = 'http://' . $changeLink;  
}

// ….

echo "<a href=\"" . $changeLink . "\" target=\"_blank\"></a>";

###

I believe David’s answer is the proper way to do this, but it can be simplified like this:

parse_url($aProfileInfo['Website'], PHP_URL_SCHEME)==''?'http://'.$aProfileInfo['Website']:$aProfileInfo['Website']