Hello, I created a custom field in the odoo GUI. A field assigned a sequence.The idea is that incremental increase its field single value when selecting a product of stockable type . CUSTOM FIELD NAME = 'x_niu'

At the view I generated the sequence , but for all products , not just for stockables products:

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I have created a method to allocate the sequence but not the custom field validation is performed : product.type =='product'         (stockable product).

_defaults = {

    'x_niu':lambda obj, cr, uid, context: obj.pool.get('ir.sequence').get(cr, uid, 'sale.order.line'),

}

def create(self, cr, uid, vals, context=None):

    if vals.get('x_niu') == None and product_id.type == 'product':

        vals['x_niu'] = self.pool.get('ir.sequence').get(cr, uid, 'sale.order.line')

    return super(SaleOrderLine,self).create(cr, uid, vals, context)

def copy (self, cr, uid, id, default=None, context=None):

    default.update({

         'x_niu': self.pool.get('ir.sequence').get(cr, uid, 'sale.order.line')

    })

    return super(res_partner, self).copy(cr, uid, id, default, context)

I hope you can help me with this problem is not how to solve it . Thanks so much.