Test-Driven Rewrite Rules

Matthew Boynes / @senyob / alleyinteractive.com

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Rewrite Rules Overview

What are they?

End Goal

/foo/bar/
↓
index.php?post_type=foo&name=bar

How do we do that?

• add_rewrite_rule()
• add_rewrite_endpoint()
• add_permastruct()

add_permastruct()

• Create a block of related rewrite rules
• Can add pagination, feeds, and other endpoints for you
• Depends on rewrite tags and rewrite endpoints

Detour: Rewrite Tags

• e.g. %my-taxonomy%
• Tags represent rewrite fragments
• %my-taxonomy%
  → ([^/]+)
  → my-taxonomy=$matches[n]

add_rewrite_endpoint()

• Adds a fragment to the end of permastructs
• e.g. Print views [url]/print/

add_rewrite_rule()

• Most direct, concrete way to add rules
• You provide the regex, the resulting query, and a relative position

In the end, one result

array(
  regex => query string,
  regex => query string,
  ...,
)

Example: Tags

'tag/([^/]+)/?$'

=>

'index.php?tag=$matches[1]'

TDD and Rewrites

1. List out the URL structure you want
2. Write a test that confirms it doesn't work
3. Build your rewrites
4. Automated tests will tell you when you've succeeded

Rewrite Testing Plugin

https://wordpress.org/plugins/rewrite-testing/

https://github.com/alleyinteractive/rewrite-testing/

Putting it all Together

Let's say we're building a recipe site

URLs

• /recipes/
• /recipes/eggplant/
• /recipes/eggplant/eggplant-parmesan/

Data Structures

• Post Type: Recipe
• Taxonomy: Primary Ingredient

URL Structures

• /recipes/
• /recipes/%primary-ingredient%/
• /recipes/%primary-ingredient%/%recipe%/

Write the tests

Filter: rewrite_testing_tests

Filters an array of test groups

Test URL => Passing match

'/recipes/' => 'index.php?post_type=recipe'

All together

function wcnyc_rewrite_tests( $tests ) {
  $tests['Recipes'] = array(
    '/recipes/' => 'index.php?post_type=recipe',
    '/recipes/eggplant/' => 'index.php?post_type=recipe&primary-ingredient=$matches[1]',
    '/recipes/eggplant/eggplant-parmesan/' => 'index.php?primary-ingredient=$matches[1]&recipe=$matches[2]&page=$matches[3]',
  );
  return $tests;
}
add_filter( 'rewrite_testing_tests', 'wcnyc_rewrite_tests' );
						

Play time!