Conditional Layouts via Filters

warning

Conditional layout code can become a maze. Keep conditions explicit, document intent, and avoid overlapping rules.

Conditional Layouts via Filters Explained

Filter	What it changes	Example condition
generate_sidebar_layout	Sidebar placement/visibility	is_page( 'landing' )
generate_content_layout (example)	Content container style	is_single()
body_class	CSS targeting	is_post_type_archive()

Why It Matters

• Different templates need different layouts (landing vs blog vs product).
• Filters let you apply those decisions without template overrides.
• This approach is version-controlled and reviewable.

How It Works

GeneratePress calls apply_filters() during layout decisions. Your child theme returns the value you want based on the request context.

flowchart LR
  REQ[Request] --> COND[Conditional check]
  COND --> RET[Return layout value]
  RET --> OUT[Layout output]

Practical Walkthrough

Step 1: Find Layout Filters in GeneratePress

find-layout-filters.sh

cd /var/www/html/wp-content/themes/generatepress
grep -R "apply_filters( 'generate_" -n inc/structure inc | head -n 80

Step 2: Implement a Filter in the Child Theme

wp-content/themes/generatepress-child/inc/filters.php

<?php

add_filter( 'generate_sidebar_layout', function( $layout ) {
    if ( is_page( 'landing' ) ) {
        return 'no-sidebar';
    }

    return $layout;
} );

Step 2b: Find Valid Return Values (Optional)

find-sidebar-layout-values.sh

cd /var/www/html/wp-content/themes/generatepress
grep -R "no-sidebar\|left-sidebar\|right-sidebar" -n inc 2>/dev/null | head -n 60 || true

Step 3: Keep a Condition Table for Your Site

Page type	Desired layout	Implementation
Landing pages	No sidebar	Filter + specific page slug
Blog posts	Right sidebar	Default or filter
Checkout	No header/footer	Layout element or filter

Practical Examples

Example 1: No Sidebar on All Pages Using a Template

If you use a dedicated page template, target it with is_page_template().

Example 2: Add a Body Class for Landing Pages

wp-content/themes/generatepress-child/inc/filters.php

<?php

add_filter( 'body_class', function( $classes ) {
    if ( is_page( 'landing' ) ) {
        $classes[] = 'is-landing';
    }
    return $classes;
} );

Example 3: Conditional Layout for Products (If WooCommerce)

wp-content/themes/generatepress-child/inc/filters.php

<?php

add_filter( 'generate_sidebar_layout', function( $layout ) {
    if ( function_exists( 'is_shop' ) && is_shop() ) {
        return 'no-sidebar';
    }
    return $layout;
} );

Best Practices

Practice	Why
Keep conditions narrow	Prevents unexpected layouts
Prefer one rule per intent	Easier debugging
Document return values	Avoid magic strings
Test logged-out	Caching differences
Keep a rule inventory	Prevents overlap
Prefer IDs for critical pages	Slugs can change

Troubleshooting

Symptom	Cause	Fix
Filter has no effect	Wrong filter name	Confirm with grep in the parent theme
Layout changes randomly	Overlapping rules	Consolidate conditions and document
Changes not visible	Cache	Purge LSCache

Hands-On

1. Find two layout-related filters in GeneratePress.
2. Implement one condition (no sidebar on one page).
3. Add a body class and write a small CSS rule for that class.
4. Add one more condition (product/shop or archive) and confirm no overlap.
5. Write a short rule table in README (page -> layout -> implementation).

Quick Reference

conditional-layouts-cheatsheet.sh

cd /var/www/html/wp-content/themes/generatepress
grep -R "apply_filters( 'generate_" -n inc/structure | head

What's Next

• Next: Accessibility & Semantics
• Related: Global Layout Framework