Question

I´m woring on a costum meta-box for wordpress. Trouble is wordpress only seems to retain/save some of the values I enter in the fields.. I can´t really find a pattern either.. so here’s the code:

<?php
function add_products_metaboxes() {
    add_meta_box('sra_product_info', 'Product Information', 'sra_products_info', 'product', 'side', 'default');
  }
  // The Productinfo Metabox
function sra_products_info() {
    //get access to the post object
    global $post;
    // Noncename needed to verify where the data originated
    echo '<input type="hidden" name="productmeta_noncename" id="productmeta_noncename" value="' .
    wp_create_nonce( plugin_basename(__FILE__) ) . '" />';
    // Get the data from the field if its already been entered
    $name = get_post_meta($post->ID, '_name', true);
    $price = get_post_meta($post->ID, '_price', true);
    $includes = get_post_meta($post->ID, '_includes', true);
    $supports = get_post_meta($post->ID, '_supports', true);
    $version = get_post_meta($post->ID, '_version' , true);
    $extrainfo = get_post_meta($post->ID, '_extrainfo', true);
    // Echo out the form
   echo '<form>';
    echo '<label for="_name">Name</label>' . '<input type="text" name="_name" value="' . $name . '"/>';
    echo '<label for="_price">Price</label>' . '<input type="text" name="_price" value="' . $price . '"/>';
    echo '<label for="_includes">Includes</label> <textarea name="_includes" rows="4" cols="10">' . $includes . '</textarea>'; 
    echo '<label for="_supports">Supports</label> <input type="text" name="_supports" value="' . $supports . '"/>';
    echo '<label for="_version">Version</label>' . '<input type="text" name="_version" value="' . $version . '"/>';
    echo '<label for="_extrainfo">Extras</label> <textarea name="_extrainfo" rows="4" cols="10">' . $extrainfo . '</textarea>'; 
   echo '</form>';

}

// Save the Metabox Data
function sra_save_product_meta($post_id, $post) {
    // verify this came from the our screen and with proper authorization,
    // because save_post can be triggered at other times
    if ( !wp_verify_nonce( $_POST['productmeta_noncename'], plugin_basename(__FILE__) )) {
    return $post->ID;
    }
    // Is the user allowed to edit the post or page?
    if ( !current_user_can( 'edit_post', $post->ID ))
        return $post->ID;
    // OK, we're authenticated: we need to find and save the data
    // check if the field exists in the posts array - if it does, then put cintent in $product_meta.
    // this code needs to be refactored!

if (isset($_POST['_name'])) {
    $product_meta['_name'] = $_POST['_name'];    
    }

 if (isset($_POST['_price'])) {
    $product_meta['_price'] = $_POST['_price'];    
    }

if (isset($_POST['_includes'])) {
    $product_meta['_includes'] = $_POST['_includes'];    
    }

if (isset($_POST['_supports'])) {
    $product_meta['_supports'] = $_POST['_supports'];    
    }

if (isset($_POST['_version'])) {
    $product_meta['_version'] = $_POST['_version'];    
    }

if (isset($_POST['_extrainfo'])) {
    $product_meta['_extrainfo'] = $_POST['_extrainfo'];    
    }


    // Add values of $prpduct_meta as custom fields
    foreach ($product_meta as $key => $value) { // Cycle through the $product_meta array!
        if( $post->post_type == 'revision' ) return; // Don't store custom data twice
        $value = implode(',', (array)$value); // If $value is an array, make it a CSL (unlikely)
        if(get_post_meta($post->ID, $key, FALSE)) { // If the custom field already has a value
            update_post_meta($post->ID, $key, $value);
        } else { // If the custom field doesn't have a value
            add_post_meta($post->ID, $key, $value);
        }
        if(!$value) delete_post_meta($post->ID, $key); // Delete if blank
    }
}
add_action('save_post', 'sra_save_product_meta', 1, 2); // save the custom fields

Do you see any obvious mistakes? I think I’ve become a bit blind to my own mistakes in this code..

Answer 1

In general, I would advise to use prefixes for your field names. Values like _name have too much chances getting in conflict with other values with the same name elsewhere. Use things like _product_name, etc. Can you try that? If your code works with pages, it should have an impact.
And why not adding the 4th parameter with ‘true’ to add_post_meta() and previous value for update_post_meta()? See WordPress codex about these functions: http://codex.wordpress.org/Function_Reference/add_post_meta. So it would go:

        if(get_post_meta($post->ID, $key, FALSE)) { // If the custom field already has a value
        update_post_meta($post->ID, $key, $value, /***OLDVALUE***/ ); // See http://codex.wordpress.org/Function_Reference/update_post_meta for old value
    } else { // If the custom field doesn't have a value
        add_post_meta($post->ID, $key, $value, true);
    }

I think it is clear you have a conflict with a metakey with the same name. Not in pages, but in posts. So try to use this 4th parameter to ensure you are referencing a unique key (and my advice, still, use clear prefixes to differenciate from anything else, be it plugins, core, etc.)