iamtgc

Implementing a Lightbox in WordPresss

tgc — Thu, 01 Mar 2012 16:29:46 +0000

The problem that I have encountered while researching various options for implementing a JavaScript lightbox in WordPress, is that they generally require you to add either a class, id, or rel attribute to your image link. This may not be an issue for newly authored content, but for those of us with a large volume of existing content, it can be a nightmare.

One solution proposed on Fancybox’s Tips & Tricks page, is to apply the lightbox only to those tags whose href attribute ends with .jpg, .png or .gif:

$("a[href$=.jpg],a[href$=.png],a[href$=.gif]").fancybox();

This may work for many situations, but it could have unintended consequences depending on your content, so I chose a different approach.

The lightbox I ended up going with is Colorbox, but many others exist, and this article should apply to a majority of them with minimal modification.

If you’ve read any of my other articles you know I usually prefer to avoid using plugins, especially for these simple tasks.

Once you’ve downloaded the lightbox of your choice, choose a location to place the javascript and accompanying stylesheet, in this example I’ve placed both in /js. Then place the following in functions.php. This example uses a child theme, if you’re not, you should replace get_stylesheet_directory_uri() with get_template_directory_uri().

function tgc_scripts_method() {
    wp_register_script( 'jquery.colorbox',
                        get_stylesheet_directory_uri() . '/js/jquery.colorbox-min.js',
                        array( 'jquery' ) );
    wp_enqueue_script( 'jquery.colorbox' );
}

add_action( 'wp_enqueue_scripts', 'tgc_scripts_method' );

Next you’ll need to add the relevant css and javascript to header.php, as in functions.php above, this assumes a child theme. If you’re using a parent theme, replace the stylesheet_directory parameter with template_directory in the bloginfo function.

Last, we need to modify our tags to include a rel attribute with the value of colorbox. We do this by adding a filter to the_content. This avoids having to update each post or modify the database. Additionally, if we change our mind on which lightbox we want to use, or how we’re invoking it, the modifications will be a lot simpler.

The regular expression we will use targets tags which link to an image (.jpg, .png, or .gif) and where the link text is an tag of the same image. For example:

Here is what you’ll need to add to functions.php

function tgc_colorbox_content_filter( $content ) {
        $url_regex = '/(<\/a>)/i';
        $url_replace = '$1 rel="colorbox" $4';

        return preg_replace( $url_regex, $url_replace, $content );
}

add_filter( 'the_content', 'tgc_colorbox_content_filter' );

Move the Navigation Bar in a Twentyeleven Child Theme

tgc — Fri, 17 Feb 2012 02:58:33 +0000

If you don’t like the default location of twentyeleven’s navigation bar, there’s good news, the theme is coded in such a way where it’s very simple to move with just a few lines of CSS.

As I’ve mentioned in previous articles, you’re strongly encouraged to tackle this using child themes.

First we begin by inspecting the current theme with Firebug. Since the navigation bar is the element we’re interested in, that’s the one we’ll inspect with Firebug. We’re interested in the layout as seen in the image below.

As it turns out, the height of the navigation bar is 43px, that gives us all the information we really need to know to move the navigation bar.

Here’s what our child theme’s style.css looks like.

/*
Theme Name: iamtgc Theme Development
Description: Child theme for the Twenty Eleven theme
Author: tgc
Template: twentyeleven
*/

@import url("../twentyeleven/style.css");

#branding { padding-top: 43px; }

#branding #searchform { padding-top: 43px; }

#access { position: absolute; top: 0; }

And here’s what our new theme looks like once it’s activated.

Add Pinterest’s “Pin It” Button To Your WordPress Blog

tgc — Thu, 02 Feb 2012 00:15:10 +0000

Even if you haven’t been fortunate enough to receive a Pinterest invite yet, chances are you’ve seen their “Pin It” button somewhere in your daily browsing. Fortunately you don’t need an invitation to add the “Pin It” button to your website. In this article I will show you how to add the “Pin It” button to your WordPress blog.

To get an understanding of the API, you can visit Pinterest’s Goodies page, and scroll down to the section labeled “Pin It” Button For Websites. There you’ll see the following code generator.

Once you begin populating the fields, your changes are reflected in the code window. As you may notice, the URLs you’re Pinning will need to be URL encoded.

In order to implement this code generation in WordPress, we’ll get the URL of the webpage the pin is on using

The URL of the image to be pinned using the post’s full sized featured image.

And for the optional Description of the Pin, we’ll use the post’s title

When we put it all together, here’s what the relevant excerpt of our loop-single.php will look like. If you want to include the Pin Count along with the “Pin It” button, you can change the count-layout attribute to either horizontal or vertical.

>

     Pin It

PostgreSQL Database Encryption

tgc — Tue, 13 Sep 2011 14:01:49 +0000

For last decade data breaches and data losses of Social Security numbers, credit card numbers, or one of a slew of other pieces of private information, have landed businesses on the front page of major newspapers, and in some instances with legal liability.

I knew when I had an opportunity to work an application which handled sensitive information, that it had to be done with the protection of this information as the number one priority.

I began familiarizing myself with the application by starting with the PostgreSQL database back-end. The pgcrypto module was present, but none of it’s functions were currently in use.

For the remainder of the article, we will take a look at how to use some of the pgcrypto PGP encryption functions to encrypt sensitive data.

First we will need to create our table. For the purposes of our example, the table will contain only one column.

CREATE TABLE messages (
   message bytea
);

Next we need to create our PGP keys. This process is outlined in the PostgreSQL pgcrypto documentation here.

Once we’ve created our PGP keys we can test the encryption functionality using the below Python code. Here we are using the public key to encrypt the word “testing” and inserting the result into our table.

#!/usr/bin/env python

import psycopg2

conn = psycopg2.connect("dbname='crypto_test' user='tgc' host='localhost'")

curs = conn.cursor()

f = open("public.key", "r")
key = f.read()

curs.execute("INSERT INTO messages (message) VALUES (pgp_pub_encrypt('testing', dearmor('%s')))" % (key))

conn.commit()

Did it work? Let’s see what was actually inserted into our table.

crypto_test=# select * from messages;
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             message
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 \301\301N\003~_\240V\321\032$\006\020\010\000\271H9\327\224\0336\245:\242\202\352B\232\314\261\2263\032#Z\343\344\365;m\333\337\3226`\352\344\017H\304\373|\213\022\246\343$\351Z\307\366`<\266\206<\330\332\024\203xX\270S\261\317\\\317\336bz\241\307\337\333`\203\020\311J?Y\013\331\021b{\220[S\011\032eu\374s\265l\336JiD\217\364P\275\272\004i\220\214\205\3111\206<\361\025%\235+U\253\202\340\250V\247\361\310\334f\307\322x=>\315x\263;\307w\335\351~--\363\350\361]5)\203\327"\254vk4o\211\244s^r\301\310\374=\312L\347\233\263\232\256~\337\033tM>\012\001C\200\345\303r\326\354{\005\3149\314\211\246\210\273\002~Z\317\270p\237\376\307\025\377r\370\221G\324\306\303\355'\301\020\357/\2049\342\222}\327K\321\347\322+\343Y\220C\027vn\027\356V-\203\355\311\033\355A)\277\266\224\256\022\007\377_\031:\015\345-\264Rj~n\207\240/\370D\3143z\305k\245/f'\004\230r[\207\321H\240a^\247\015\037\351\276!~\354\031\314~)\224\364r\354\036\337\376\006\024K\300ih\335\377\011\256C\262\253\016\210ZN\272\231{\332\304\303\332\003;\221\022\004\275\335\330$\027v\355\004,f\2713\266\352\311\027\326\316\3742LMM\353\037\222C\264\240\275>,\210o\326\212F_@G\306\276\274\332\247\256\336\027U\377\224\313\221>b\355\003K\300\231c
Well, that’s certainly a far cry from “testing”.
Now for the code that decrypts our message.
#!/usr/bin/env python

import psycopg2

conn = psycopg2.connect("dbname='crypto_test' user='tgc' host='localhost'")

curs = conn.cursor()

f = open("secret.key", "r")
key = f.read()

curs.execute("SELECT pgp_pub_decrypt(message, dearmor('%s')) from messages" % (key))

rows = curs.fetchall()

for row in rows:
    print row[0]

Let’s try running our decryption script
$ python ./test-decrypt.py
testing

Note: depending on the type of data you are encrypting, the functions pgp_pub_encrypt_bytea and pgp_pub_decrypt_bytea are also available.

Exploring Triggers in MySQL and PostgreSQL

tgc — Mon, 15 Aug 2011 13:25:37 +0000

Recently I was working on a car maintenance database. The database stores, among other things, odometer reading, miles per fill up, number of gallons per fill up, and cost per gallon. One of the missing pieces of information I wanted to report on is the miles per gallon I was achieving. While this is trivial to insert, I didn’t want to modify the client which was already deployed and running. Since the data to determine this value was already present, I turned to database triggers to help me record this value.

Wikipedia describes “A database trigger is procedural code that is automatically executed in response to certain events on a particular table or view in a database.”

In our case, the procedural code we want to execute is the computation of our miles per gallon, and the event we are responding to is an insert into our table. In this article I will outline how to create these triggers in both MySQL and PostgreSQL.

Our triggers will be applied to the following table.

CREATE TABLE mileage (
   miles float,
   gallons float,
   mpg float
);

The following was tested in MySQL 5.5.14, but should work on other versions as well.

Let’s create our trigger. The key things to note here are BEFORE INSERT, since we want to insert the mpg value along with the miles and gallons, and NEW, since we are referring to a column of a new row to be inserted.

-- MySQL
CREATE TRIGGER trig__mileage BEFORE INSERT ON mileage FOR EACH ROW SET NEW.mpg  = NEW.miles / NEW.gallons;

Now with our trigger created, we can test to see if it fires correctly. If it fires correctly, we can expect our mpg column to be populated, otherwise it will be NULL.

-- MySQL
INSERT INTO mileage (miles, gallons) VALUES ( 250, 10 )

SELECT * FROM mileage;
+-------+---------+------+
| miles | gallons | mpg  |
+-------+---------+------+
|   250 |      10 |   25 |
+-------+---------+------+

Success! It really is that simple. Additional documentation, including more complex examples, can be found here.

Now on to PostgreSQL. These were tested on PostgreSQL 8.3.15, but should work on other versions as well.

The first thing to note is the CREATE TRIGGER statement in PostgreSQL takes a user supplied function as an argument. This function must return type TRIGGER, and in our instance will be responsible for calculating our miles per gallon.
In our function we use the NEW variable, which holds the new database row for insert.

-- PostgreSQL
CREATE OR REPLACE FUNCTION trig_proc__calculate_mpg() RETURNS TRIGGER AS $_$
BEGIN
   NEW.mpg := NEW.miles / NEW.gallons;
   RETURN NEW;
END $_$
LANGUAGE plpgsql;

With our function created, we now create the trigger.

-- PostgreSQL
CREATE TRIGGER trig__mileage BEFORE INSERT ON mileage FOR EACH ROW EXECUTE PROCEDURE trig_proc__calculate_mpg();

And now to test if our trigger fires correctly.

-- PostgreSQL
INSERT INTO mileage (miles, gallons) VALUES ( 312.3, 12.1 );

SELECT * FROM mileage;
 miles | gallons |       mpg
-------+---------+------------------
 312.3 |    12.1 | 25.8099173553719

As you can see, our trigger has populated the mpg column. Additional documentation on triggers in Postgres can be found here and here.