On the pitfalls of date validation with the Zend Framework

PHP • Web development • Zend Framework June 21st, 2010

I'm writing this post as a warning for people using Zend_Date to validate dates, either as a standalone or as a validator in a chain. I've been using Zend_Validate_Date validator, which uses the Zend_Date::isDate() method internally, for a while now - mainly for form processing.

I've recently completed a project where a very bizarre bug would occur on some machines, and I wasn't able to reproduce it myself on any test machine that I tried. The bug manifested in a calendar system we built for the project, and in certain situations form submissions would not pass the date validation through Zend_Validate_Date, despite using the exact same input that was passing on the test machines.

After bringing in one of the "affected" machines for testing, I used the process of elimination to determine the problem originates in the Zend_Date::isDate() method, which has different behavior on different machines.

Zend_Date tries to validate dates according to a given format (with a default fallback). The dangerous behavior is that it tries to convert the given format to a localized format using Zend_Locale. Zend_Locale attempts to detect automatically the locale of the requesting client, and it appears that on the machines that were exhibiting the bug, a different locale was determined than those I was testing it on.

Despite trying to validate a non-localized format (to be exact, the MySQL timestamp format - YYYY-MM-dd HH:mm:sss), it was being converted on the affected machine sdue to the auto-detection by Zend_Locale (on a side note - it was happening on Internet Explorer 8 on Windows 7). To avoid this issue, I set the locale for all requests manually to en_US, since I don't have any other use for Zend_Locale in the application. I put the following lines in the bootstrap -

$locale = new Zend_Locale('en_US');
Zend_Registry::set('Zend_Locale', $locale);

As recommended by the manual to achieve this effect.

In my opinion, the Locale should be not be auto-detected by default - it should be an opt-in feature if it affects other components behind the scenes.

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Fetching specific rows from a group with MySQL

MySQL • Web development March 12th, 2010

In a normalized database, we store separate entities in separate tables and define relationships between them, those being - one-to-one, one-to-many and many-to-many. We often want to fetch data which is split over two or more related tables, which is dead simple when fetching the extra data from the 'one' side of a relationship (ie, from a "parent" table):

SELECT product_images.src,products.name
FROM product_images
INNER JOIN products ON product_images.parent_id=products.id

Literally: Get the name of the parent product for each row in the products_images table.

Going the other direction is not as trivial. If we just want all the referenced rows in the child table, the query seen before would do the trick. But if we wanted a specific row to be found - for example, the latest inserted image, it becomes somewhat more complicated.
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Creating embedabble widgets

CSS • Javascript • Web development February 5th, 2010

Distribution of embeddable widgets is a common feature in many web services today. The most well known example is probably google's adsense that allows site owners to add google ads to their sites. Embeddable widgets allow a subset of functionality to be used on third-party sites, greatly increasing possible market reach for a web service / application.
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Back to business

Web development January 26th, 2010

After a long hiatus, I'm getting back to blogging on web technologies, startups and other miscellanea. I've just completed a re-design of the site, which I'm proud to say I've done myself (with some finishing touches and advice from my two partners at Lionite).

I'm looking forward to expand discussion on some subjects I've brought up in the past (especially models in the Zend Framework) as well write on some of things we've been doing lately. Hope you will find it useful / interesting.

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How to add semantics to content? embed it in the tools

Interesting • The Webs September 2nd, 2009

Through reading an interesting post by Chris Dixon titled "To make smarter systems, it's all about the data", I came across another interesting link in one of the comments - the google research blog post on "The unreasonable effectiveness of data".

The post links to a PDF document written by three Google researchers, and covers a subject I've been experimenting with a lot lately - the semantic extraction of data.
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