event-rest-route.php

<?php
//--REST ROUTE FOR CUSTOM POST TYPE EVENTS
//--THIS IS WORKING
add_action( 'rest_api_init', function(){
	register_rest_route( 'event-search/v1', '/search/', array(
		'methods' => 'GET',
		'callback' => 'getResults'
	));	
});

//--REGISTER THE START DATE META TO A EVENT REST REQUEST
//--THIS IS NOT WORKING
//--WHEN I SWITCH THIS FROM 'EVENT' TO 'POST' I GET THE METAS BACK IN THE REST REQUEST
//--DOES NOT RETURN ANYTHING AT ALL WHEN SWITCHED TO MY CPT.
add_action( 'rest_api_init', function(){	
	register_rest_field( 'event', 'event_start_date', array(
		'get_callback' => 'getStartDate',
		'update_callback' => null,
		'schema' => null
	));
});

//--GET CUSTOM POST TYPE META
function getStartDate( $object, $field_name, $request ){
	return get_post_meta( $object['id'], 'banner_image', true );
}

//--HANDLE THE REST REQUEST
//--GRAB ALL POSTS IN THE EVENTS POST TYPES
//--WITH THE SUBMITTED CATEGORY(TAXONOMY), LOCATION(TAXONOMY) AND DATE(META FIELD GENERATED THROUGH PODS PLUGIN)
//--THIS IS 100% WORKING
//--PERHAPS THIS QUERY IS PREVENTING THE META (LINE 12) FROM SHOWING?
function getResults( WP_REST_Request $request ){
	$category = $request->get_param( 'cat' );
	$location = $request->get_param( 'loc' );
	$date 	= $request->get_param( 'date' );
	$page 	= $request->get_param( 'page' );

	$posts_per_page = 2;

	if( $page <= 0){
		$page = 1;
	}

	$query_params = array (
		'cache_results' 		=> true,
		'update_post_meta_cache' => true,
		'update_post_term_cache' => true,
		'post_status' 			=> 'publish',
		'post_type' 			=> 'event',
		'ignore_sticky_posts' 	=> true,
		'posts_per_page' 		=> $posts_per_page,
		'paged'				=> $page,
		'meta_query' 			=> 
			array (
			    0 => 
				    array (
				     	'key' 	=> 'event_start_date',
				     	'value' 	=> $date,
				     	'compare' => '>=',
				     	'type' 	=> 'DATE',
				    ),
			  ), //event_start_date
		array (
			0 => array (
			     0 => array (
					'taxonomy' 	=> 'events_category',
					'field' 		=> 'name',
					'terms' 		=> array ( 0 => $category, ),
					'operator' 	=> 'IN',
			     ), //events_category
			     1 => array (
					'taxonomy' 	=> 'events_locations',
					'field' 		=> 'name',
					'terms' 		=> array ( 0 => $location, ),
					'operator' 	=> 'IN',
				), //events_locations
				'relation' => 'AND',
			    ),
		  ), //array with tax params
	);

	$query = new WP_Query();

	$results = $query->query( $query_params );

	$data = array();
	if( !empty( $results ) ){
		foreach( $results as $post ){
			$data[] = $post;
		}

		return $data;
	}else{
		return new WP_Error( 'te_no_event_posts', 'No Events', array( 'status' => 404 ));
	}
}

Created my taxonomies and cpts, the old fashioned way (php). I'm using the Pods plugin to create the date meta fields. I made sure to enable REST on those meta fields in the Pods settings. Not sure if that's the deal. But when I test with another meta that, like say, grabbing the featured image URL, it still doesn't work. So I don't think it's anything to do with the Pods plugin, Must be something with adding the extra meta fields to a custom post type response. Another thing it could be, is my meta query in general. I'll give it a shot with a basic CPT query.

Is this v1 or v2 REST API?

And you're certain that the registered cpt slug = event? As well as certain that the post_meta key = event_start_date?

https://gist.github.com/rpasillas/8c4516a866e4de138ca35d3b8b0f4baf#file-event-rest-route-php-L25

shouldn't the field be event_start_date instead of banner_image?

I don't know how i missed your replies @jacobarriola.

1. REST API V2.
2. Certain on both accounts
3. You're correct, i updated it to banner_image for the sake of this gist, however, when it was event_start_date it was behaving the same.