Web Scripting: reading an xml file in php and convert it into an associative array

Today, I will write about How to read an xml file from a source url/address and convert it into an array finally so that we can parse and use it. The code is so simple if you are using php 5.0 or higher. If you don't have php 5.0 or higher, this solution below is not for you. It has another solution which involves a few more lines of code.

Let's start with an url of a xml feed. Here is the link of BBC News Front page World Edition.

http://newsrss.bbc.co.uk/rss/newsonline_world_edition/front_page/rss.xml

This page shows the latest world news in an xml feed. Now, if you want to read that front page using a php script and use those news in your website, what you should do ?

I know, there may be lots of brilliant widgets to show the latest world news to a website, But i am just taking this as an example of how to parse that xml feed and I am considering you one of the future coder of those widgets.

Here is the code.

$SimpleXML_object = simplexml_load_file("http://newsrss.bbc.co.uk/rss/newsonline_world_edition/front_page/rss.xml");   
print_r($SimpleXML_object);
echo $SimpleXML_object->channel->title ;

The above code will output something like this. This was the output at the moment I was writing this.

This magic here, it is done by a single function simplexml_load_file() which is supported from php 5. This function converts the well-formed XML document in the given file to an SimpleXMLElement object.

This xml data in SimpleXMLElement Object, you can access these data as shown in the third line of the code, $SimpleXML_object->channel->title will give you the title of the feed. You have to use the schema of the xml to get the correct data.

Now, I want to convert this SimpleXMLElement Object into an associative array. Personally, I like to deal with associative arrays rather than this Object to avoid type casting and other things.

Usually, I use the following function to do this, I like this one because, it doesn't add the attributes and I don't need that. But if you need those attributes, you may check for some other functions here. Probably, I picked the following function from this page too.

function convertXmlObjToArr( $obj, &$arr )

    {
        $children = $obj->children();
        $executed = false;
        foreach ($children as $elementName => $node)
        {
            if( @array_key_exists( $elementName , $arr ) )
            {
                if(@array_key_exists( 0 ,$arr[$elementName] ) )
                {
                    $i = count($arr[$elementName]);
                    convertXmlObjToArr ($node, $arr[$elementName][$i]);    
                }
                else
                {
                    $tmp = $arr[$elementName];
                    $arr[$elementName] = array();
                    $arr[$elementName][0] = $tmp;
                    $i = count($arr[$elementName]);
                    convertXmlObjToArr($node, $arr[$elementName][$i]);
                }
            }
            else
            {
                $arr[$elementName] = array();
                convertXmlObjToArr($node, $arr[$elementName]);   
            }
            $executed = true;
        }
        if(!$executed&&$children->getName()=="")
        {    
            $arr = (String)$obj;
        }
        return ;
    }

Usage of this function : the full code will look like this

$SimpleXML_object = simplexml_load_file("http://newsrss.bbc.co.uk/rss/newsonline_world_edition/front_page/rss.xml");
$XMLDataAraay = array();
convertXmlObjToArr($SimpleXML_object, $XMLDataAraay);
print_r($XMLDataAraay);

And now, you will be able to access the title this way. $XMLDataAraay['channel']['title']

Here, the last step of converting the Object into an Array may seem unnecessary. You can avoid this and deal directly with the object too.

And, Here is the new problem. If your site where you are going to use and extend this code to show data, this script will load the xml file every time from BBC's server. But every time, it is getting the same page unless this feed is updated in every minute.
2 problems are there I can remember of it for now,
One, it is consuming your server's valuable bandwidth and another is the slower response of fetching the file first and then processing it.

Solution : solution of this kind of problem is Caching. You can save a cache of the xml file with a suitable timeout and a timeout mechanism.. This system will save a copy of the xml file and every-time you request this file, this mechanism will look for the Cached file if the timeout interval (say, 15 minute, this means, we are expecting that this new feed will not be updated in next 15 minutes or, we can allow this maximum delay of getting that new news) of that cache file hasn't reached. If the cache file has timed out, it will refresh the cache file with new one and deliver it.

Sounds too much complex ? Actually, it is just a few lines of php code. I will discuss it some other day. :)

1 comments :: reading an xml file in php and convert it into an associative array

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July 3, 2014 at 1:41 AM

Web Scripting

reading an xml file in php and convert it into an associative array

1 comments :: reading an xml file in php and convert it into an associative array

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