How to check a single number value against an array of meta_key values?

Question

There seems to be a ton of information on checking a meta_key against an array of meta_values, but I want to do the opposite.

I have a site with projects, and press reviews. When the client adds a review, they have a custom field (ACF) to select the project it relates to from a list.

I am now trying to display all press reviews that relate to a certain project, together on a page. I have the project ID, and use a query with $args to select the press reviews I want.

My current $args:

$args = array(
    'post_type'     =>  'pressreview',
    'order'         =>  DESC,
    'meta_query' => array(
        array(
            'key' => 'belongs_to_project',
            'value' => $projectID,
            'compare'   => 'LIKE'
        )
    )
);

The problem is, that custom field 'belongs_to_project' returns an array with IDs. One press review can be about multiple projects, so I let the client pick multiple projects from the list in that field. A typical array will be like this:

Array ( [0] => 210 [1] => 202 ).

What I want to do, is check whether the $projectID is in that array.

In the current setup, it sort of works: if the client selected 202 and 210 from the list, and the $projectID is 210, the press review is shown. However, if the $projectID = 20, we get press reviews for projects 201, 202, 203, etc. (since those numbers include '20', which is how LIKE works)

Is there any way I can tell this query to only check for 'whole' numbers? So that "2" would only show reviews for project 2, and not for 201, 202, or any other numbers that have a 2 in them?

I've seen there is a REGEXP option to use instead of LIKE, but I can't find out how to use it in a way that it checks for only 'whole numbers'.

I've also tried 'IN', but that doesn't work at all here.

One thing that I thought of, but don't know whether it's possible at all, is to use something like:

'key' => 'belongs_to_project[$i]'

with some kind of loop through the key values, so that $projectID could be checked with '=' instead of LIKE against each of the values in the array of the custom field. I've no idea if there's any such option and how it should be written.

Hope my explanation is clear enough, please let me know if I need to explain better.

Answer 1

The solution was that I need to compare the literal value of $projectID, so that LIKE compares an exact string instead of just numbers. To make $projectID literal, it needs to be wrapped in quotes.

So, I changed this line:

'value' => $projectID,

to:

'value' => '"'.$projectID.'"',

Which solves the problem.

Answer 2

I believe that you should use IN at compare but you said this's not working. and I notice something (please forgive me if this's a mistake ): you write example for array

Array ( [0] => 210 [1] => 202 ).

this mean the value in array is NUMERIC and the Default type is 'CHAR'. so you can try

$args = array(
    'post_type'     =>  'pressreview',
    'order'         =>  DESC,
    'meta_query' => array(
         array(
            'key' => 'belongs_to_project',
            'value' => $projectID,
            'compare'   => 'IN',
            'type'     => 'NUMERIC'
         )
     )
);