Tag Archives: Technical communication

PHP: Does SimpleXMLElement have toString() method? No, better use asXML()!

SimpleXML is a PHP extension that “provides a very simple and easily usable toolset to convert XML to an object” [1]. Thus you can pass a link to an XML file and SimpleXML will return an object.

$xml = simplexml_load_file('path_to_the_file');

Sometimes you’d need to dump or save the entire XML as a string, but there’s no toString method! As you can see $xml is an instance of the SimpleXMLElement class.

var_dump($xml); // object(SimpleXMLElement)...

Actually if you take a closer look:

$xml->toString();

will return “Call to an undefined method toString()”, which is frustrating because the developers community is used to use toString() when converting an object into a string.

XML
PHP's SimpleXML doesn't have toString() method. asXML() is used instead!

The solution

In fact there’s a method doing exactly what’s needed. This is SimpleXMLElement::asXML

As described in the manual page: “SimpleXMLElement::asXML — Return a well-formed XML string based on SimpleXML element” [2].

Besides that it does exactly what’s needed it sounds irrelevant, because you’ve an XML object and the name “asXML” doesn’t describe correctly what’s expected.

$xml->asXML() // ?!
  1. SimpleXMLElement::asXML
  2. SimpleXML Introduction

How to Collect the Images and Meta Tags from a Webpage with PHP

Meta Tags and the Facebook Example

You’ve definitely seen the “share a link” screen in Facebook. When you paste a link into the box (fig. 1) and press the “Attach” button you’ll get the prompted cite parsed with a title, description and possibly thumb (fig. 2). This functionality is well known in Facebook, but it appears to be well known also in various social services. In fact Linkedin, Reddit, Dzone‘s bookmarklet use it.

Facebook Attach a Link Prompt Screen
fig. 1 - Facebook Attach a Link Prompt Screen

Fist thing to notice is that this information, prompted by Facebook, is the same as the meta tag information. However there is a slight difference.

Facebook Attached Link Screen
fig. 2 - Facebook Attached Link Screen

Facebook prefers for the thumb the image set into the <meta property=”og:image” … />. In the case above this tag appears to be:

<meta property="og:image" content="http://b.vimeocdn.com/ts/572/975/57297584_200.jpg" />

And the image pointed in the SRC attribute is exactly the same as the one prompted by Facebook (fig. 3).

Vimeo Thumb
fig. 3 - Vimeo Thumb

First thing to note is that the real thumb is bigger than the thumb shown in Facebook, so Facebook resizes it and the second thing to note is that there are more meta tags of the og:… format. Continue reading How to Collect the Images and Meta Tags from a Webpage with PHP

Wanted – onfocus/onblur. Why They Don’t Work Always!

On Focus

onfocus

Perhaps you think of onfocus and onblur events as a default behavior existing in any web page. This is not quite true! Onfocurs and onblur are well known in web developing (js) and are fired, of course, when the user tries to point something or leaves some element. Onfocurs is fired when the user either goes to an element with the Tab button on with the mouse. When the element is on focus, evidently, the onfocus event is fired. Actually you can see which element is on focus, like an anchor or input, when the element is outlined by the browser by default. In the same scenario, when some element has been on focus and than the user switches to another element, the onblur event is fired. Thus you may guess that this element is no longer on focus. Continue reading Wanted – onfocus/onblur. Why They Don’t Work Always!

jQuery: Get the Selected Option Text

What’s the Task?

First of all let me explain what is the task. If there’s a select menu with several options, each of which are with a given value attribute, the task is to get the text into the option tag, and not that of the value attribute.

In that scenario let’s assume that we have the following HTML:

<select id="my-select">
    <option value="1">value 1</option>
    <option value="2">value 2</option>
</select>

select menu
Note that in the official jQuery doc page, the selector is described in the same context, but with a different markup:

<select id="my-select">
    <option>value 1</option>
    <option>value 2</option>
</select>

than the jQuery snippet looks like that:

$(document).ready(function() {
    $("#my-select").change(function() {
        alert($(this).val());
    });
});

Here’s interesting to note that there’s no value attribute set to the options, thus the selection of an element is correct and the returned value is correct. The problem is that this code doesn’t work correctly once you’ve a different value attribute, from the value enclosed into the option tag. In our case we’ve the markup shown on the first code snippet and we’d like to get the “value 2” string instead of “2”.

Source Code

<select id="my-select">
    <option value="1">value 1</option>
    <option value="2">value 2</option>
</select>
$(document).ready(function() {
    $("#my-select").change(function() {
        alert($(this).val());
    });
});

Solution

Finally the solution, is pretty simple and clear, but this time is not to so “native” and it’s definitely something you couldn’t expect! The only thing you’ve to do is to change the selector!

$(document).ready(function() {
    $("#my-select).change(function() {
        alert($('#my-select option:selected').html());
    });
});

How to Sanitize User Input in PHP?

It’s a question almost every PHP developer asks yourself. By me the most simple way to sanitize the user input is to save everything in the database with no loosing of tags or whatever HTML markup and than on displaying this on the client side to strip_tags if needed.

In example when saving a HTML formatted text you can use simply the htmlspecialchars method

$description = htmlspecialchars($_POST['description']);

Than you can be sure everything’s in the database, but it’s not actually HTML. Thus you don’t have any tags at all in the database field.

When you show this in the client side and you’d like to strip some tags, i.e. to keep only the <a> tag you can do this:

echo strip_tags(htmlspecialchars_decode($description), '<a>');

That’s the most simple way to keep everything as the original source. By me it’s better to keep whatever HTML markup there is on the input.