Category Archives: Web Development

Check out my jQuery beginners Article at iprodeveloper.com

The article Dive Into jQuery (Part 1 appears in the April online and print editions of iProDeveloper.com. The target audience is primarily IBM i developers, but it’s actually a good introduction for anyone, regardless of server-side technology, who wants to learn jQuery.

Using Laravel: How To Use Routes, Controllers and Filters For Public and Private sections of a CMS site

If you are reading this you probably already know what Laravel is, but just in case: it’s a PHP framework for building applications. It has all the typical stuff such as MVC, DAO, ORM, a templating engine (also supports Twig from Symfony), routes, controllers, clean URLs, RESTful support etc. I really like it because it’s very clean and compact to code in. It’s also much simpler to get started with than something like Zend Frameworks 2, for example, as it doesn’t require a complex install process or configuration. In fact it pretty much just runs out of the box.

Other Tutorials on Laravel

There are a few (very few) tutorials on Laravel. If you prefer learning by watching videos I can highly recommend this series by Andrew Perkins. One text-based tutorial I’ve been working through is Dayle Rees’s. One weakness of his articles is that he starts out showing you how bits hang together, but by the time you get to filters he loses the plot and stops giving you a step-by-step working example- he teaches you concepts but doesn’t show them all working together. This is the case with his discussion about securing an admin section of your site, for example. Another tutorial, written by Nikko Bautista, covers some of the same ideas. That one also leaves some gaps. So here’s my attempt to provide a full working example, along with an explanation of how all the bits and pieces relate to one another.
Continue reading

New Version of jQuery UI Feedback plugin

The jQuery UI Feedback plugin I wrote lets you show an informational or error message next to a UI component on your page. Its primary intended use is for AJAX-driven applications, where you want to provide some instant feedback to a user. You can read documentation, download it and try it out at this page on this blog.

I just updated it to provide a common class for each feedback message, named “ui-feedback”. This gives you the ability to turn off existing feedback messages by using this selector:

jQuery(".ui-feedback").hide();

You might want to do this if multiple feedback messages potentially overlap one another.

Let me know if you find this plugin useful!

How to access cross-domain data with AJAX using JSONP, jQuery and PHP

I’m guessing that if you are reading this post you have already encountered the problem of the same origin policy with regards to retrieving data with AJAX from urls in other domains than your’s (the requesting domain). This policy, enforced by browsers, means you cannot fetch raw data from other domains with straight AJAX calls.

The Problem I Was Trying To Solve (skip this paragraph if you just want the solution)
Here’s the situation I ran into. At work, we have a timesheet entry program running on one subdomain, and Flyspray (bug-tracking software) on another subdomain. We wanted to get task descriptions from Flyspray integrated in our employee timesheet notes. Basically, the employee types a Flyspray task # for a given task they are working on, anywhere in their timesheet log entries. A jQuery script then converts that task # into a link to the task. In addition, that same script lets the user just hover over the task # to see a summary description of the task. When they hover, jQuery fires an AJAX request to a PHP script on the Flyspray subdomain. I couldn’t get it to work, so after researching it on jQuery sites I discovered my need for JSONP.

JSONP Circumvents the Same Origin Policy
Data returned from an AJAX call in JSONP (JSON with padding) format is designed to solve this problem. In jQuery, you can specify that you want either JSONP or JSON data returned from your AJAX calls. The differences between the expected returned formats of JSONP and JSON data are as follows:

  • JSON returns a JSON-formatted object only. For example: { "id" : "mydomelementid", "message": "This data came from a server!"} . This is a JSON object with 2 properties, id and message, and their corresponding values. See json.org to find out more about JSON.
  • JSONP returns a JSON-formatted object wrapped inside a function call. For example: jsonp123( { "id" : "mydomelementid", "message": "This data came from a server!"}); .

JSONP works by injecting what looks like a local function call directly into your script, attaching it to a script tag (in the form of a url). Wikipedia has a great explanation of this.

jQuery makes it easy to do AJAX calls implementing JSONP. You can use the simple getJSON method, or the ajax method. I’ll show you examples using both. First, though, let’s look at some example PHP code, so you know how to code the server side stuff. This part is what was not clear to me when I started researching JSONP.

The Server-Side Code (PHP)
In our example, we want to return a JSON object with a property of “message” that contains some feedback text to show the user when they click a button.

<?php
header("content-type: application/json"); 

// Create a generic object.
// Assign it the properties of id (optional - id of target HTML element, from URL) 
// and 'message' - the feedback message we want the user to see. 
if (isset($_GET['id'])) $rtnjsonobj->id = $_GET['id']; 
$rtnjsonobj->message = "You got an AJAX response via JSONP from another site!";


// Wrap and write a JSON-formatted object with a function call, using the supplied value of parm 'callback' in the URL: 
echo $_GET['callback']. '('. json_encode($rtnjsonobj) . ')';    

?>

This script returns a string in JSON-formatted object notation, wrapped in a function call. The name of the function comes from the URL parameter ‘callback’. The JSON object has one expected property (“message”) and one optional one, “id”. You provide the “id” parameter value on the URL string, also. I’ll explain its use in the second jQuery example. So, let’s say we call our script jsonp.php. The url to call it could look like this: "http://www.example.com/jsonp.php?callback=jsonp123". What json.php writes back to the server will be: json123({"message": "You got an AJAX response via JSONP from another site!"}); . If this were a JSON call instead, we’d omit – json123(); – the function call wrapper.

(Note our PHP script creates an object on the fly, without declaring a class and instantiating one. Our object is an instance of the stdClass class, a generic PHP object. Just assigning a property to it: $rtnjsonobj->;message = "You got an AJAX response via JSONP from another site!"; achieves this. The json_encode function then converts the PHP object to a JSON-formatted string. )

The Client-Side Code (jQuery)
I’ll show you 2 examples using jQuery AJAX functions to get the message produced by jsonp.php. The first example uses the typical jQuery anonymous callback function programming pattern. The second uses a named callback function.

Example 1

$(document).ready(function() {
 $("#jsonpbtn").click(function() {
	var surl =  "http://www.fbloggs.com/sandbox/jsonp.php?callback=?"; 
	var me = $(this); 
	$.getJSON(surl,  function(rtndata) { 
		me.feedback(rtndata.message, {duration: 4000, above: true});
    }); 
 });
}); 

This example is the simplest implementation of JSONP with jQuery. It calls our PHP script jsonp.php, passing a single parameter on the URL – callback=?. This specific syntax is the key to this being considered a JSONP AJAX call, rather than a JSON call. Note that the method is still getJSON- not getJSONP. The callback=? convention tells jQuery to generate a random function name and pass that as the value of the parameter named callback. Recall that our PHP script gets this function name with $_GET[‘callback’] , so we don’t have to worry about the actual generated name. Then, the anonymous function call (the second option on the getJSON method) does the work. In this case, it references the jQuery object that was clicked (the variable me) and calls my feedback plugin to display the message text. The fragment rtndata.message means ‘get the message property of the object rtndata (the JSON object returned by our PHP script). Feedback simply displays the message above the clicked button, for 4 seconds.

Example 2
This example uses a named callback function. Note that this capability is only supported in jQuery 1.4, so make sure you have the latest and greatest installed. As of this post, I’m using 1.4.2. I’m not sure why you would want to use a named callback function, other than to conform to DRY. The jQuery docs mention obliquely that you might want to cache your AJAX responses, but they give no explanation of how or why. Anyway, I thought it was worth trying, so here it is:

$(document).ready(function() {
$("#jsonpbtn2").click(function() {
	var surl =  "http://www.fbloggs.com/sandbox/jsonp.php"; 
	var id = $(this).attr("id"); 
	$.ajax({
		url: surl, 
		data: {id: id},
		dataType: "jsonp",
		jsonp : "callback",
		jsonpCallback: "jsonpcallback"
		}); 
 });
}); 

// Named callback function from the ajax call when jsonpbtn2 clicked
function jsonpcallback(rtndata) { 

	// Get the id from the returned JSON string and use it to reference the target jQuery object.
	var myid = "#"+rtndata.id; 
	$(myid).feedback(rtndata.message, {duration: 4000, above: true});
}

In this case, we can’t use the shorthand getJSON method, because it doesn’t have enough options. Instead, we must use the longer form ajax method. No big deal.
Here’s what’s going on. First, note the URL does not contain the callback=? parameter. Instead, we use the options jsonp and jsonpCallback, which is like writing: "jsonp.php?callback=jsonpcallback" for our url. Next, we pass the id of the DOM element (button) we clicked, as another parameter on the URL. Recall that our PHP script looks for this, and if it finds it, sends it back as a property of the returned JSON object. Next, we specify the expected data type returned from our server-side script (JSONP).

The cycle of code execution for this example is:

  • User clicks button with id of jsonbtn2
  • The browser invokes the $.ajax() method
  • The AJAX call invokes the server-side script, jsonp.php
  • jsonp.php gets the button’s id from the url parameter, constructs a JSON object with id and message properties and writes it back to the browser
  • The browser responds by running function jsonpcallback. It expects one parameter- our returned JSON object.
  • jsonpcallback retrieves the clicked button’s id from the returned JSON object, constructs a valid jQuery selector with it, and calls the feedback plugin to display the message above the button, just like in the simpler anonymous function example.

You should now understand why we pass the id back and forth. We need it in order to keep track of which element we are acting upon. We didn’t need to do this in the first example because of the magic of closures, another big topic.

That’s it!

See The Examples At Work
I’ve posted this page to show you working examples. You can view source if you want to see the jQuery code. It should be identical to what I’ve posted.

Considerations When Using JSONP
JSONP relies on injecting a script tag into your page. A side effect of this is that if you have errors in the data returned by your server, you won’t see any errors- the script tag just fails silently. An example of an error might be an incorrect callback function name (only likely in scenarios using Example 2 coding pattern), or malformed JSON.

When I first tried coding this, I got a Firebug error of ‘Invalid Label’. This totally uninformative error is the result of not wrapping the JSON object in a function call. In other words, if you have existing server code that writes JSON objects, it won’t just magically work with JSONP. Your server code must wrap a function call around the object, as I’ve shown.

Because JSONP relies on the script tag, it doesn’t use the callback features of the underlying HTTPRequest object. This means the success, failure, complete callback functions on the $.ajax() method are irrelevant and nonfunctional when you use JSONP.

How To Assign The Current Date and Time to a MySQL Datetime Field using PHP

This is a no-brainer, but I always forget how to do it. MySQL datetime fields are stored in this format: 2010-02-18 10:33:18. Here’s a trivial example showing you how to populate a datetime field with the current date in the correct format, then write it to a table:

 // Assign current date to a MySQL date field:
 $eventdate = date('Y-m-d H:i:s');
 //... (mysql connection code goes here)
 mysql_query("INSERT INTO Events (Event, EventDate) VALUES ($eventtext, $eventdate)");

Another question might be: “Why?” – when MySQL has the now() function. I needed to do this in Drupal, because I’m using the drupal_write_record function to update a table in a custom module. This requires assigning PHP values to fields in my table, rather than using any built-in MySQL functions.

How To Embed A Google Calendar Gadget In Your Web Site

Google provides two simple ways, other than you writing your own client code to talk to their APIs, to embed a calendar in your web page. One method is easily found by Googling for the info. This link explains how you can generate a piece of code directly from your calendar settings page, which you then paste into your page. This code uses a simple iframe. The other method is to use a Google Gadget. While they are primarily meant to embed in iGoogle, you can also embed them in your own site. Here’s how:

  1. Log in to the Google account that owns the calendar you want to embed.
  2. Make sure the sharing option is set to public (if that’s truly what you want!)
  3. Go to this URL:    http://www.google.com/ig/directory?hl=en&url=www.google.com/ig/modules/calendar3.xml. This is a Google gadget.  Note the last part of the URL – calendar3.xml .  DO NOT use calendar.xml . It doesn’t work any more (as I found out to my chagrin when the  calendar for our local soccer club web site suddenly stopped rendering for no apparent reason).
  4. You’ll see a link in the bottom right hand side of the page, titled: Embed this gadget >> , which means ‘Embed this gadget in some page other than at iGoogle’.   Click on this link .
  5. Customize the gadget’s appearance with the available options. You should see the changes you make reflected immediately. If not, click ‘Preview Changes’.
  6. Once you are happy with the final appearance, click ‘Get the code’
  7. Select the generated code in the text box, copy and paste it into your page.

The gadget uses an XML feed via web services to draw the content directly in the page, as opposed to using an Iframe, which for a Geek like me is a much more elegant solution than more easily found one. Plus, I like the fact you get a monthly calendar with a list of upcoming events directly below it. (When you customize the gadget’s appearance, change the height to 400px, for example, and you’llsee what I mean).

You can see a working example at Saanich Peninsula Soccer Club’s site.

How to correct font size problem with tables in jQuery UI widgets

I just recently used jQuery UI tabs in an application. Within a couple of the tabs I used tables for content (let’s not have a religious debate about using tables for layout, please). Anyway, the font size came out much bigger than for text in a paragraph, for example- in FireFox. I looked at the custom.css file (generated by themeroller, called jquery-ui-1.7.2.custom.css) and found this line:

.ui-widget input, .ui-widget select, .ui-widget textarea, .ui-widget button { font-family: Lucida Grande, Lucida Sans, Arial, sans-serif; font-size: 1em; }

This line is designed to handle form input types, to make sure the font size matches text in other tags such as paragraphs, etc. However, text in tables also needs to have these rules applied. To fix the problem, I copied this line and added table as a descendant selector, like so:

.ui-widget table { font-family: Lucida Grande, Lucida Sans, Arial, sans-serif; font-size: 1em; }

(You could also just add .ui-widget table to the overall selector).

Problem solved.

You might also be interested in reading this earlier post on How to scale the jQuery UI font size just for just the ui widgets.

Joomla 1.5 has wrong path for css, js files – edit your configuration.php file

I just moved a Joomla 1.5 install from my iMac to a hosted site. The home page showed up fine, but subsequent pages were missing all styles. It turns out that I needed to change the variable $live_site in configuration.php from ” to = ‘http://www.example.com/mypath’. I’m not clear on why it worked on my MAMP install but not on the ISP, but apparently this is a common Joomla 1.5 install problem, as noted at this Joomla forum thread. (Scroll down to see Anthony Ferrara’s (aka ircmaxell) response on Feb 21, 2008 – ignore all the other bogus parts of the thread). Anthony is apparently a member of the core development team, on the bug squad. Thanks, Anthony!

Using Aptana Studio 2.0 and PDT Plugin for Drupal Module Development

Aptana now uses the official Eclipse PDT (PHP Development Tools) plugin instead of their own PHP editor. I have Aptana 2.0.2, build date November 10 2009 on my Macbook.  I’m building a Drupal module, so I need to have PDT recognize (and correctly color-code) files with .module, .info and .install extensions.  There is a Drupal Article on configuring PDT as an Eclipse Plugin, but the steps are different for doing it in Aptana Studio.

The process is quite simple – basically 3 steps. Here they are (assuming you’ve got the PDT plugin installed already):

In Aptana Studio, click on the Aptana Studio/Preferences, expand the General link and click on Content Types: Aptana Preferences General tab

Next, expand the Text link. This will show you a list of content types supported in the editor. Scroll down until you see the PHP entry:

Aptana Content Types Associated with Editor

You’ll see the usual PHP extensions listed in the bottom box, such as php, php3, php5. Click on the Add button to the right to add an extension needed for Drupal Module development. You’ll see a dialog like this:

Aptana Define New Content Type Association

Click OK. Repeat this step for *.info and *.install (assuming these extensions are not already used for some other language or tool). That’s it! Now, when you open a .module file, it will have the same color-coding and editing as a .php file.

Articles I’ve Written on IBM i (iSeries) Technology Subjects

I’ve written a few articles in recent years that have been published by MC Press Online, relating to IBM i topics. If you don’t know what the IBM i is (or an AS/400, iSeries or System i), you can stop reading! Here are two lists of links to those articles. The first list is general education. The second is product-specific, related to products marketed by my company. (Articles are ordered by most recent first)

Educational Articles

Product-Specific Articles