Design Avarice

In this tutorial I will teach you how to make your very own WordPress Plugin. I will show you how to make an options page in the admin panel, add and change plugin options and more.

WordPress has very good plugin support and so it is fairly simple to make a working plugin. To start off I will show you the basic structure of a plugin file.

The above code is read by WordPress and the info is displayed the plugins admin panel. All the fields are self explanatory.

You need to put the code you want to be executed on your plugin admin page in a function so that when you register the page with WordPress it knows what to show.

First we make a function that tells WordPress to add a new submenu under the Options tab (options-general.php), make the title of the page My Cool Plugin page, name the tab My Cool Plugin, have the tab point to this file and the function mycoolpluginintialize. The 10 is the priority of this function, this can generally be left at 10. Next we call the WordPress function add_action(), this takes two parameters, when to do this action, and what function to call when this action is supposed to be run. admin_menu is a hook in the WordPress admin interface we can use call our add page function and addmyplugintoasubmenu is the function we use to add our options page.

And now here is the full sample code:

Not as confusing as you though eh? You can try and save that in a file in your plugins directory and it will work. Try activating it, it doesn't do much but it's a start.

You might be asking how do I make my plugin a sub-page of a different tab. Simple, change options-general.php in the above example to the name of a different admin page, here are some admin pages:

• Dashboard - index.php
• Write - post.php
• Manage - edit.php
• Links - link-manager.php
• Presentation - themes.php
• Plugins - plugins.php
• Users - profile.php
• Options - options-general.php
• Import - import.php

Now lets make a plugin that will add an introduction to the home page of your blog and make that introduction editable in the admin panel. To start we will do something similar to the above except with a few extra functions that will check if the admin form has been submitted and output the introduction to the template.

It's a good idea to give your plugin functions and options a unique prefix (hepa_intro_) because WordPress will crash if it detects dual function names. The code above tells WordPress some info and makes the function that will display the intro. Any functions declared in a plugin can be used in a template so to add the intro to any template we will simply call this function.

The form has no action, this will simply submit the form to the same page. The submit button is in a specialy themed paragraph tag to make it look pretty. And now for the last part, adding the admin page and then adding the intro into a template.

The above code simply adds the admin page. The whole plugin code:

The last thing we need to do is to add the intro to the home page of our template. Each template is different so I will show you the code to use and where to put it in the default template. In the WordPress admin interface go to the Presentation tab, make sure your blogs template is the default one, then go to the Theme Editor tab. On the right select the template file Main Index Template. Now find the following code:

And add the following code before it:

The code you add might be different if you changed the name of the function. Also you might need to put the code elsewhere depending on the template you are using.

Thats it! Now make sure you upload the plugin file to the wp-content/plugins/ directory, active it, and fill in the options, and the intro should show up on your blog homepage.

The plugin you made in this tutorial is very simple, one feature you might want to add is remembering the options you have set in the options page so you don't have to re-write the whole introduction every time you want to edit it.

If you have questions or comments use the form below and let me know! If you liked this tutorial please think about registering.

This entry was posted on Wednesday, December 20th, 2006 at 11:09 am and is filed under Tutorials. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.