JavaScript uses url-encoded UTF-8 strings to perform Ajax POSTs

Today, I had an encoding issue with a website I was working on. I had a

tag in the <head>-section, to ensure the page would correctly display and interpret all characters, including accented ones, like à and é.

The page was an administration page, to update texts on a website. Everything worked fine when I used standard <form> and <input>-tags, but I wanted to use Ajax to save any changes – to avoid a full page reload when something simple as a title had to be modified – things started to go wrong.

I used the spectacular jQuery library to do that, using a $.post-statement. At first sight, this seemed to be working fine, until I used some accented characters. When I entered “Soirée Théâtre” as title, the characters “Soirée Théâtre” were stored in the database.

I first thought it was an issue similar to the Bulgarian character set issue in mySQL I encountered a few months ago. But I was just using French in this case, so iso-8859-1 and mySQL character set “latin1_swedish_ci” should suffice in this case.

After some googling, I found this website, that explained that in the case of Ajax POSTs, “JavaScript serializes all the fields and it always uses url-encoded UTF-8 strings for this”. A simple utf8_decode in the PHP program that received the Ajax post-statement solved my issue.


Experimenting with Adobe AIR and jQuery – Part 4

For the next step in my Top100-application, I wanted to introduce some animation. In step 3, the information on the slide and the background color changed when I pressed the UP or DOWN key, but that happened immediately. I wanted to use some PowerPoint-like animation.

The jQuery UI library extends jQuery with interaction and animation options.

The first thing I tried was to make the new number pulsate a few times after it changed. I downloaded the library, added it to the code and added a pulsate effect:

That worked fine.

I then wanted to have the number, artist and title disappear by sliding to the right, then changing the background color and information, and then have the new information appear from the left. So I tried this:

And that didn’t work, or at least, not as expected. The background color and in the information changed immediately, at the same time the sliding to the right started. So for a second or so, you could already see the next number, artist and title, on a red background, while it was sliding to the right. It looked like all events happened simultaneously.

It took a while before I understood that that was exactly what was happening. When pressing the DOWN key, all events are happening at the same time. Well, almost all. The .show effect needs to wait for the .hide effect to complete, but the background color and changing of the text is happening at the same time as the .hide effect. We need a way for jQuery operations to wait until a previous event is finished.

This is probably an area that could have get a bit more attention on the jQuery documentation pages. Finally I found the solution at the detached designs website. There I learned how to “queue” animations. You need to use the callback features of jQuery. A callback is a function that is passed as an argument to another function and is executed after its parent function has completed. To make the background and text only change after the .hide effect, I needed to add this as a new function:

This did what I wanted: the text was first sliding to the right, then the background color changed (and the text changed as well, but that was not visible).

I finally added the .show effect and made the number pulsate, again only after the .show effect was finished:

♦ Related files: step4.html


Deleting similar records in MySQL

If you have a table in MySQL with duplicate records, you can easily get a list without the duplicates by using the DISTINCT keyword in the SELECT-statement:

If you want to delete the duplicate records, you can create a new table without the duplicates, by combining the CREATE TABLE statement with SELECT DISTINCT:

However, if you have similar records, where some, but not all fields are the same, the DISTINCT approach does not work. This is an excerpt of a table with songs:

title artist cd track
Amazing Seal 317 3
Crazy Seal 128 12
Crazy Seal 287 16
Don't You Simple Minds 152 5

I’d like to delete the similar records, keeping just one entry for each artist/title combination. The SELECT DISTINCT statement will not work, as none of the records are exact duplicates. In other words,

will return the same table.

I could do a

which results in

title artist
Amazing Seal
Crazy Seal
Don't You Simple Minds

but I want to keep the information in the other columns.

The solution in MySQL is to use the multiple-table syntax for the DELETE statement using the same table twice:

For the example above, I could use

which results in

title artist cd track
Amazing Seal 317 3
Crazy Seal 128 12
Don't You Simple Minds 152 5