WordPress Theme

Development

Part II

Who am i?

● Owner of QC Creative, a local digital

marketing and web development agency

● Web developer for over 10 years

● Since 2010, 90% of projects have been in

WordPress

● @joshleecreates

Quick Review

PHP Basics

PHP allows logic

operations with

variables:$x = 1;

$y = 2;

$z = $x + $y;

And with functions:

echo( ‘Hello, World’ );

$post_title

= get_post_title();

PHP Basics

Conditionals:$x = true;

if( $x == true ) {

echo( ‘x is true’);

}

x is true

Loops:$x = 0;

while( $x <= 10 ) {

echo( ‘x is: ‘ . $x

);

}

x is: 0

x is: 1

x is: 2

...

Template Tags

Template tags allow you to use a small PHP

snippet to inject values from your WordPress

database into a pagethe_title();

the_content();

the_excerpt();

the_post_thumbnail();

Output or retrieve data

`the_` tags output

content directly into

the page:

<h1>

<?php the_title(); ?>

</h1>

`get_` tags retrieve

values which can be

manipulated first:<h1>

<?php

$title = get_the_title();

echo( $title );

?>

</h1>

Conditional Tags

`is_` template tags return a boolean

(true/false) value, useful for conditional

statements:is_single();

is_page();

is_category();

is_page( ‘about-us’ );

The Template Hierarchy

WordPress determines what kind of view is

being requested, and combines the content

for that view with a specific template (PHP

file) from the theme.

The “Template Hierarchy” determines which

PHP template is used for which views.

The Template Hierarchy

http://codex.wordpress.org/Template_Hierarchy

Anatomy of a Request

How does WordPress build a page?

How does WordPress build a page?

1. User requests page

2. WP initialized

3. Plugins initialized

4. Theme initialized

5. Query type

identified

6. Template

identified

And finally…

The page is rendered

by processing the

chosen template

together with actions

and filters

“Theme Initialized” = functions.php

● functions.php is the first part of

the theme to get run

● It is always run after plugins are

initialized

Common Functions

● Enqueue scripts and styles

● Modify queries for specific pages

● Modify plugin or WP core behavior (actions)

● Modify plugin or WP core output (filters)

● Declare theme support

● Include other PHP libraries

What is Theme Support?

What is theme support?

● add_theme_support()

● Tells WP which features your theme can

support

● E.g.: featured images, HTML5 markup, etc.

● http://codex.wordpress.org/Function_Refe

rence/add_theme_support

Hooks, Actions, & Filters

Doing it the WordPress way

What are Hooks?

A hook is an anchor associated with a specific

event within WordPress

E.g.:

● A page is requested

● A query is run

● the_content() is output for a post or page

● A user logs in

What are actions? Filters?

Actions & Filters are functions that you

define, and attach to a specific hook.

Which means…

We can tell WordPress:

● Whenever doing X, first do Y

● E.g.:o Whenever loading the blog homepage, first add my

custom post type to the query