Recently a client wanted to know if we could have the same blog appear on two different sites with two different domain names. I told her yes, we could. Then I had to go figure out if we actually could.
Yes, kids, your web designer often doesn’t know how to do something until they surf the web and teach themselves how to do it. Self-instruction and a sense of adventure are a big part of this job. The technology field is always changing and there are always new things to be learned. It’s part of the reason this job is fun, because you constantly get to solve new puzzles and do things you didn’t know you could do.
My client was Erin Bried, author of How to Sew a Button: And Other Nifty Things Your Grandmother Knew. That book was so successful that her publisher signed her to write a sister book (er, brother book?) called How to Build a Fire: And Other Handy Things Your Grandfather Knew. Erin already had a blog for the “Button” site, and since both sites have the same how-to theme, she wanted the same blog to appear on both of them.
When I’m trying to learn how to do something new, I start by Googling keywords I think will lead to the answer. This led me to discover three possible ways to solve the problem:
Option #1: Modify the database prefix
This solution required that you install two copies of WordPress on the same host using the same database. (Note: This is not the same as setting up WordPress’s multi-blog option. Instead, these are two independent WordPress installations in separate folders on your web server that are using the same database.) You can install two copies of WordPress in the same database if you specify that they use different table prefixes. By default, all the tables in a WordPress installation start with “wp_” but you can change it to whatever you want in the wp-config.php file.
After you’ve installed both copies of WordPress, you then go into your second installation’s wp-config.php file and rename the table prefix to be that of the first installation. The second WordPress blog will now draw on the data from the first installation, but will remain separate.
This solution seemed way too risky for me to try on Erin’s sites since her first website was live and receiving steady visitors. Messing with the database and the configuration files in this way left a big opportunity for things to go horribly, horribly wrong. I also wasn’t sure if such a modification might screw up any WordPress updates I’d have to install in the future. So, I continued Googling.
Option #2: Crossposting plugin
If you activate the Xpost plugin on your blog, whenever you write a post it will also be posted at another blog that you specify, as long as that blog supports posting via XML-RPC. If someone comments on that post at either site, the comment will be posted on both sites. Having two sets of duplicate data can lead to problems if things get out of synch, but this seemed to be the best solution to the problem that I could find.
I installed the plugin, but because Erin’s sites are both managed within the same WordPress installation using the multiple blog option, the plugin wouldn’t work properly. Thus, I abandoned this approach.
However, as I was Googling for the link to that plugin to include in this post, I found another plugin called Cross Post which claims to work with WordPress MU, though I can’t verify whether it works or not. Regardless, I’m glad I hit a roadblock because it led me to ultimately find a better way to solve the problem.
Option #3: Theme switching
Stumped, I went to the kitchen and made a peanut butter sandwich. By the time I was done chewing, I had thought of another approach to the problem—theme switching. The Theme Switcher plugin allows visitors to use any theme installed on your site by adding the string ?wptheme=ThemeName to the end of the query string. I installed the plugin, visited the original blog with the “Button” theme, added the proper query string to the end of the URL to display the new theme, and voila! The original blog was being displayed with the new theme!
One problem: Now all the pages on the original blog were being displayed with the new theme. Not good. Once you switch the theme, it remains switched until you change it to something else or delete the cookie stored in your browser. I didn’t want visitors of Erin’s “Fire” site to head over to her “Button” site and see the wrong template.
To overcome this issue, I wrote a snippet of code to insert into the header of the new theme that made sure to load the proper theme at the right time:
if (is_page() && ($_SERVER["SERVER_NAME"]=='www.originalThemeSite.com') ) {
if (! empty($_COOKIE["wptheme" . COOKIEHASH]) && $_COOKIE['wptheme' . COOKIEHASH]!= 'Original theme name') {
$expire = time() + 30000000;
setcookie(
"wptheme" . COOKIEHASH,
stripslashes('Original theme name'),
$expire,
COOKIEPATH
);
$redirect = remove_query_arg('wptheme');
wp_redirect($redirect);
exit;
}
}
This code first checks to see if you’re visiting the original site (not the new one) and if you’re on a page in the site (not a blog archive, search results page, individual entry, etc. which should display the new template). This checks to be sure you’re on a page that should display the original theme, not the new one. If that’s true, it then checks to see if you’ve got a cookie from the Theme Switcher plugin and if that cookie is not set to the original theme. If that’s true, it resets the cookie to the original theme name and reloads the page.
Once those changes were uploaded, the theme switching ran perfectly. To make the link to the blog a bit easier to remember, instead of http://www.domainname.com/blog?wptheme=ThemeName I used the Redirection plugin to send any visitors of http://www.domainname.com/blog to the theme-switched address instead. The same can be achieved by editing the .htaccess file, but I like using the plugin because it allows you to make changes within WordPress without having to FTP.
One other thing to note is that if you have more than two themes installed on your multiple WordPress installation, someone could hypothetically switch the theme of the blog to any of the other themes if they know their names. In that case, it’s good to only install the themes you need, and if you want to be extra safe you can add the code I listed above into the templates of all the themes on your installation.
