WordPress Interview questions – for theme developers with answers

A WordPress Theme is a collection of template and style sheets. In WordPress Dashboard WordPress themes are in Appearance–> Themes . You can change any theme from here.

Create a theme folder in /wp-content/themes/ folder

/wp-content/themes/custom-theme

Create index.php and style.css file in custom-theme folder. In style.css write

<?php
/*
Theme Name: My Custom theme
Theme URI: https://curiouswebs.in/
Author: curiouswebs
Author URI: https://curiouswebs.in/
Description: Well Responsive HTML 5 Custom theme
License: GNU General Public License v2 or later
License URI: http://www.gnu.org/licenses/gpl-2.0.html
Text Domain: twentyseventeen
Tags: one-column, two-columns, right-sidebar, flexible-header, accessibility-ready, custom-colors, custom-header, custom-menu, custom-logo, editor-style, featured-images, footer-widgets, post-formats, rtl-language-support, sticky-post, theme-options, threaded-comments, translation-ready
This theme, like WordPress, is licensed under the GPL.*/

Now theme is ready to install via Appearance > Themes > Custom theme > just activate it.

A basic WordPress theme has following files

index.php : main template file

style.css : For styling theme

header.php : header content

footer.php : footer content

page.php : template for wordpress pages

front-page.php : template for home page or front page

singular.php : template for post details page. If it is not found page.php is used. if page.php is not found index.php is used.

single.php : template for post details page

single-{post-type}.php : template for specific post type detail page.

archieve-{post-type}.php : template for listing of all the posts

page-{slug}.php : template for specific page

category.php : template for category

tag.php : template for tags

taxonomy.php : template for custom taoxnomies

author.php : template for author pages

search.php : template used for search results

404.php : template used for when page is not found.

date.php : template used for post details when url is date wise.

comments.php : template for comments.

get_header() : To include header file in a template

get_footer(): To include footer file in a template

get_sidebar(): To include sidebar in a template.

get_search_form(): To include search form

get_template_part() : To include a template part in theme

Using wp_nav_menu() function. Parameters passed to this function are menu name, title,location,menu wrapper id or class etc.

Basic Syntax is

<?php
wp_nav_menu( array $args = array(
    'menu'              => "", // (int|string|WP_Term) Desired menu. Accepts a menu ID, slug, name, or object.
    'menu_class'        => "", // (string) CSS class to use for the ul element which forms the menu. Default 'menu'.
    'menu_id'           => "", // (string) The ID that is applied to the ul element which forms the menu. Default is the menu slug, incremented.
    'container'         => "", // (string) Whether to wrap the ul, and what to wrap it with. Default 'div'.
    'container_class'   => "", // (string) Class that is applied to the container. Default 'menu-{menu slug}-container'.
    'container_id'      => "", // (string) The ID that is applied to the container.
    'fallback_cb'       => "", // (callable|bool) If the menu doesn't exists, a callback function will fire. Default is 'wp_page_menu'. Set to false for no fallback.
    'before'            => "", // (string) Text before the link markup.
    'after'             => "", // (string) Text after the link markup.
    'link_before'       => "", // (string) Text before the link text.
    'link_after'        => "", // (string) Text after the link text.
    'echo'              => "", // (bool) Whether to echo the menu or return it. Default true.
    'depth'             => "", // (int) How many levels of the hierarchy are to be included. 0 means all. Default 0.
    'walker'            => "", // (object) Instance of a custom walker class.
    'theme_location'    => "", // (string) Theme location to be used. Must be registered with register_nav_menu() in order to be selectable by the user.
    'items_wrap'        => "", // (string) How the list items should be wrapped. Default is a ul with an id and class. Uses printf() format with numbered placeholders.
    'item_spacing'      => "", // (string) Whether to preserve whitespace within the menu's HTML. Accepts 'preserve' or 'discard'. Default 'preserve'.
) );

For more information check this link.

register_sidebar() function is used to create a sidebar . There are basically two steps to create it.

Step 1: Register a custom sidebar widget area

<?php
function curious_webs_widget() {
    register_sidebar( array(
        'name' => __( 'Blog Page Sidebar', 'curiouswebs' ),
        'id' => 'blog-page-sidebar',
        'before_widget' => '<div class="blog-page-sidebar">',
        'after_widget' => '</div>',
        'before_title' => '<h1 class="widget-title">',
        'after_title' => '</h1>',
    ) );
}
add_action( 'widgets_init', 'curious_webs_widget' );

Step 2: Call this widget in theme wherever required.

<?php if ( !function_exists('dynamic_sidebar') || !dynamic_sidebar("Blog Page Sidebar") ) : ?>
<?php endif;?>

using add_role() function.

Basic Syntax is:

<?php add_role( $role, $display_name, $capabilities ); ?>

<?php
add_role(
    'guest_author',
    __( 'Guest Author', 'testdomain' ),
    array(
        'read'         => true,  // true allows this capability
        'edit_posts'   => true,
        'delete_posts' => false, // Use false to explicitly deny
    )
);

For More information check here.

add_role(): To add a role

remove_role() : to remove a role

add_cap(): to add capabilities to a role

remove_cap(): remove capabilities from a role

get_role(): get information about the role like name and capabilities.

A custom post type is a post type but have different value in database instead of default post. It can be created by using register_post_type function.

function custom_post_type_book() {
   $args = array();
   register_post_type( 'book', $args ); 
 }
 add_action( 'init', 'custom_post_type_book' );

They are used to group post together. By default wordpress has category taxonomy. However custom taxonomy can be created by using register_taxonomy function.

<?php 
add_action( 'init', 'create_book_tax' ); 
function create_book_tax() {
         register_taxonomy( 
                     'book_tax', //taxonomy name
                     'book'   // post type name
                     array( 'label' => __( 'Book Categories' ), 
                     'rewrite' => array( 'slug' => 'book_tax' ), 
                     'hierarchical' => true, )
                 ); 
} 
?>  

It is WordPress default taxonomy. They are basically used as keywords for a post.

Both are used to group posts but the difference is if the classification has some hierarchy category is used. If there is no hierarchy then tag is used. For example book categories can be Fiction -> Science Fiction -> Historical Fiction etc. and book tag can be most popular , editor choice etc.

Any custom styling or functionaliy will be lost when a theme is updated. So child theme will be created by inheriting the parent theme.So child theme allow user to add , modify parent theme functionalities without losing the ability to update its parent theme.

• create child theme folder in /wp-content/themes/default-child
• create a style sheet in this folder and add following code into

 /*
Theme Name:   Dummy Theme Child
Theme URI:    http://curiouswebs.in/parent-theme-name-url
Description:  Dummy Child Theme
Author:       AB C
Author URI:   http://example.com
Template:     dummy-theme
Version:      1.0.0
*/ 

Just copy parent theme’s file into child theme file and make changes to that file.

• contact form 7
• gravity form
• WP forms
• Ninja Forms
• Formidable forms

By using wp_redirect method.

function my_logged_in_redirect() {
 
if ( is_page( 11 ) ) 
{
wp_redirect( get_permalink( 10 ) );
die;
}
 
}
add_action( 'template_redirect', 'my_logged_in_redirect' ); 

<?php 

add_action( 'wp_enqueue_scripts', 'dummy_child_theme_enqueue_styles' );
function  dummy_child_theme_enqueue_styles () {

wp_enqueue_style( 'parent-style', get_template_directory_uri() . '/style.css' );
 
}