My b2evo version: 1.10.2

Hi everybody,
I want to add a field in the post writing: the products_id of one product of my OSC shop.

I've been able to make the conection to the OSC db to get the list of my products and put that list in a dropdown just before the title field, in the writing area.

But I can't succeed to put the selected option value in the db.
What I've done:
in the blog/inc/MODEL/items/_items_class.php,[list]I've added the products_ID in the Object Definition:

'products_ID'	  => 'post_products_ID',

I've added the var declaration in the Item class:

var $products_ID;

And also in the insert function

var $products_ID;

,

$this->set( 'products_ID', $post_products_ID );

[/list:u]
But I'm missing something because when I try to save the post, I have this error message:

MySQL error!

Field 'post_products_ID' doesn't have a default value(Errno=1364)

Your query: DataObject::dbinsert()

INSERT INTO posts (post_creator_user_ID, post_datestart, post_notifications_status, post_renderers, post_status, post_locale, post_priority, post_main_cat_ID, post_ptyp_ID, post_url, post_urltitle, post_datedeadline, post_comment_status, post_content, post_wordcount, post_title, post_datecreated, post_datemodified, post_lastedit_user_ID)
VALUES ('1', '2007-10-23 13:31:43', 'noreq', 'b2evSmil.evo_lightbox.b2evALnk.evo_videoplug.b2WPAutP.evo_code.b2WPTxrz', 'draft', 'es-ES', '3', 1, 1, '', '100_jovencitas', NULL, 'o

So, as I can see, it doesn't get the information about the products_ID and that's why it gives me this error (this field in the db is not null)

The db field and the select input both name is [u]post_products_ID[/u].
I keep searching, but is anyone has a sugestion I'm very willing to read it.
thanks, cu