REST API custom endpoint to fetch pages and posts not working

Question

I'm building a theme from scratch that will use vue.js under the hood. I'm now using the standard wordpress endpoint to fetch pages and posts, I would really create my custom endpoint to pass as a response, a custom set of data instead of the default one provided by the REST API. I've already registered a custom endpoint for the menu and it's working fine. I want now to register two more endpoints to get pages and posts, but I'm not able to make the things work. I will get a 404 or a 500 error from the endpoint and I need to fix this. To get evary page or post I'm using the slug, this mean that the GET or POST requests needs to have that parameters as querystring. I don't know if my code is correct, but I'm not able to get it inside my functions.php file. Any help will be appreciated.

functions.php

// NB: the code is part of a small class that manage the routes. the register_rest_route function
// is inside a class method and the rest_api_init is called correctly 
   register_rest_route( 'theme/v1', '/pages/', array(
      'method' => 'GET',
      'callback' => array($this, 'get_page_data')
    ));

  public function get_page_data( $request )
  {
    //var_dump( $request );
    $slug = $request->get_params('slug');
    $page = get_page_by_path( $slug, OBJECT, 'page' );  
    $page_meta = get_page_meta( $page->ID ); 
    $images = get_post_gallery_images( $page->ID );

    foreach( $images as $image_url ){
      $attachments_url[] = $image_url;
    }  

    $data = array(
      'ID' =>  $page->ID,
      'title' => get_the_title( $page->ID ),
      'content' => strip_shortcodes($page->post_content),
      'excerpt' => $page->post_excerpt,
      'page_meta' => $page_meta,
      'attached_images' => $attachments_url,
      'featured_image' => get_the_post_thumbnail_url( $page->ID )
    );
    return $data;
  }

// In the vue app js file the url for the request is 
https://mysitedomain.com/wp-json/theme/v1/pages?slug=pageslug 

Answer 1

First off, there's a default endpoint for retrieving pages, but I presumed that you intentionally did not use it?

Now the issues with your code:

1. That $request->get_params() gets all the parameters and not a single one. So for single parameters, you should use $request->get_param().

   $slug = $request->get_params('slug');  // incorrect
   $slug = $request->get_param( 'slug' ); // correct
   

2. The error 500 is likely because there's no function named get_page_meta in WordPress. Did you mean to use get_post_meta?

   $page_meta = get_page_meta( $page->ID ); // incorrect
   $page_meta = get_post_meta( $page->ID ); // correct
   // or do you have a custom get_page_meta() function?
   

3. As I already mentioned in your other question, the correct array key is methods and not method. And for the exact same callback (and parameters), you can supply an array of methods. (See below examples)

4. I'm guessing you got the error 404 because you tried to make a POST request to your custom endpoint, in which case the error is expected since you haven't added an endpoint for POST requests. So add it, like the examples here or see below:

   register_rest_route( 'theme/v1', '/pages', array(
       array(
           'methods'  => 'GET',
           'callback' => array( $this, 'get_page_data' ),
       ),
       array(
           'methods'  => 'POST',
           'callback' => array( $this, 'get_page_data' ),
       ),
   ) );
   
   // or provide an array of methods:
   register_rest_route( 'theme/v1', '/pages', array(
       'methods'  => [ 'GET', 'POST' ],
       'callback' => array( $this, 'get_page_data' ),
   ) );