[SOLVED] I want to add a new value in the post meta without deleting the old value

I want to add a new value in the post meta without deleting the old value

I have post meta "metaname" with value "thatsme" and I want to add a new value "thatsyou" in the post meta "metaname" without deleting the old value "thatsme"

so the result will be:

metaname -> New value
thatsyou -> Old value

how to do it in wordpress?

Solution

You can do this simply using add_post_meta as normal.

The 4th (optional) parameter is a boolean to indicate whether the meta key should be unique or not:

false means that you can add another entry using the same key
true means WP won't create a new entry or change the old one.

You already have a key set up, presumably using code like this:

add_post_meta( $post_id, 'metaname', 'thatsme');

To add another value, you just to the same again - I've added false for the unique parameter here to highlight it, but it is the default value so there is no need

add_post_meta( $post_id, 'metaname', 'thatsyou');

Then to retrieve all the values of the meta-key, you can do the following:

$my_meta_keys = get_post_meta( $post_id, 'metaname', false );   // get all values for this key
if ( ! empty( $my_meta_keys ) ) {
    // loop through all values 
    foreach( $my_meta_keys as $value)
        echo $value;  // or whatever you want to do with it
}

References: