Good error handling with file_get_contents

Question

I am making use of simplehtmldom which has this funciton:

// get html dom form file
function file_get_html() {
    $dom = new simple_html_dom;
    $args = func_get_args();
    $dom->load(call_user_func_array('file_get_contents', $args), true);
    return $dom;
}

I use it like so:

$html3 = file_get_html(urlencode(trim("$link")));

Sometimes, a URL may just not be valid and I want to handle this. I thought I could use a try and catch but this hasn't worked since it doesn't throw an exception, it just gives a php warning like this:

[06-Aug-2010 19:59:42] PHP Warning:  file_get_contents(http://new.mysite.com/ghs 1/) [<a href='function.file-get-contents'>function.file-get-contents</a>]: failed to open stream: HTTP request failed! HTTP/1.1 404 Not Found  in /home/example/public_html/other/simple_html_dom.php on line 39

Line 39 is in the above code.

How can i correctly handle this error, can I just use a plain ifcondition, it doesn't look like it returns a boolean.

Thanks all for any help

Update

Is this a good solution?

if(fopen(urlencode(trim("$next_url")), 'r')){

    $html3 = file_get_html(urlencode(trim("$next_url")));

}else{
    //do other stuff, error_logging
    return false;

}

Answer 1

Here's an idea:

function fget_contents() {
    $args = func_get_args();
    // the @ can be removed if you lower error_reporting level
    $contents = @call_user_func_array('file_get_contents', $args);

    if ($contents === false) {
        throw new Exception('Failed to open ' . $file);
    } else {
        return $contents;
    }
}

Basically a wrapper to file_get_contents. It will throw an exception on failure. To avoid having to override file_get_contents itself, you can

// change this
$dom->load(call_user_func_array('file_get_contents', $args), true); 
// to
$dom->load(call_user_func_array('fget_contents', $args), true); 

Now you can:

try {
    $html3 = file_get_html(trim("$link")); 
} catch (Exception $e) {
    // handle error here
}

Error suppression (either by using @ or by lowering the error_reporting level is a valid solution. This can throw exceptions and you can use that to handle your errors. There are many reasons why file_get_contents might generate warnings, and PHP's manual itself recommends lowering error_reporting: See manual

Answer 2

Use CURL to get the URL and handle the error response that way.

Simple example from curl_init():

<?php
// create a new cURL resource
$ch = curl_init();

// set URL and other appropriate options
curl_setopt($ch, CURLOPT_URL, "http://www.example.com/");
curl_setopt($ch, CURLOPT_HEADER, 0);

// grab URL and pass it to the browser
curl_exec($ch);

// close cURL resource, and free up system resources
curl_close($ch);
?>