update post meta for checkbox in the admin when inserted in the front-end

Question

Here's my problem, I allow a certain user type to create custom post type in the front-end of my site, with the wp_insert_post() function... users can put values within a form and there's couple of input types, checkboxes, ranges, numbers, and text fields.
But I have a problem with checkbox and radio inputs. when users save values, they don't appear in the post in the admin panel, I think the problem is in the update_post_meta() condition...
here how was the condition:

     if( isset( $_POST[ 'checkbox_1' ] ) ) {
        update_post_meta( $post_id, 'checkbox_1', 'yes' );
     }else{
        update_post_meta( $post_id, 'checkbox_1', '' ); 
     }

so I changed it like that:

$stored_meta= get_post_meta($post_id);

     if(isset( $_POST[ 'checkbox_1' ] ) ) {
        update_post_meta( $post_id, 'checkbox_1', $_POST[ 'checkbox_1' ]) ;
     }else{
        update_post_meta( $post_id, 'checkbox_1', $stored_meta['checkbox_1'][0]); 
     }

Now they appear, but it's impossible to modify them in the admin panel, for example if user checked an input, even if I unchek it, it remains check after update.

I have tried other logic, but they all failed.

here's how look my checkbox input:

<input type="checkbox" name="checkbox_1" value='yes' <?php if ( isset ( $stored_meta['checkbox_1'][0] ) ) checked( $stored_meta['checkbox_1'][0], 'yes'); ?>>

Answer 1

Welcome to WordPress SO.

You may already have solved the issue as suggested by @Stevish, but just in order to avoid promoting the idea of checkboxes somehow being bad or difficult, I'd like to point out, that they're perfectly okay and logical. :)

What is the problem in your first snippet, is the additional closing square bracket ']' in the value, which would cause a syntax error and thus PHP Fatal error.

Change this:

update_post_meta( $post_id, 'checkbox_1', 'yes'] );

to this:

update_post_meta( $post_id, 'checkbox_1', 'yes' );

Also, a handy way to deal with single value metadata is to specify the $key and the $single parameter like this:

$value = get_post_meta( $post_id, 'checkbox_1', true );

That way you get the single value, and not an array where your value is the [0]. That way you can skip many if( isset( $meta['whatever'][0] ) ) kind of checks. :)