How to display wp_post by custom field value?

You can’t do this by default, but you can write a query to do it within your theme. It could be a security risk to allow any field to be entered in the URL, so you’ll need to explicitly detect those that you are wanting.

In your functions.php, you could add something like this (untested!):

add_action( 'pre_get_posts', 'wpse230535_custom_posts_by_custom_field' );

function wpse230535_custom_posts_by_custom_field( $query ) {
  if( !is_admin() && $query->is_main_query() ) {

    $acceptable_fields = array( 'custom-field-1', 'custom-field-2' );
    $meta_query = array();

    foreach( $acceptable_fields as $field ) {
      if ( ! isset( $_GET[$field] ) ) { continue; }

      $meta_query[] = array (
        'key' => $field,
        'value' => sanitize_text_field( $_GET[$field] ),
        'compare' => '=',
      );

    } // end foreach

    if( count( $meta_query ) ) { $query->set( 'meta_query', $meta_query ); }

  } // end if
} // end function

This will take your allowed custom fields – currently custom-field-1 and custom-field-2, check whether they’re set in the query string (via the $_GET[] superglobal), and then if so, sanitize them and add them to a meta query.

You’ll need to replace the allowed field names with the ones you want, of course. As an example, this code would, when one visits http://www.example.com/?custom-field-1=fieldvalue, only show posts that have a custom field called custom-field-1, with the exact value of fieldvalue. You can add as many fields as you want.

For further reference on making queries by custom fields, you can see the WP Meta Query documentation. Hope this helps!

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