What does `visitor_id` is NULL at `report_viewed_product_index` mean?

Question

For example there are the rows at report_viewed_product_index:

index_id    visitor_id  customer_id product_id  store_id    added_at
19          NULL          20116     10642       2       2016-03-04 
45          NULL          20162     6246        1       2016-03-05
108         NULL          15229     20157       1       2016-03-14
190         378345      NULL        21092       2       2016-03-30
191         381787      NULL        20184       1       2016-03-30

As I understand customer_id IS NULL means that we have 'not logged customer' or visitor. What does visitor_id is NULL mean?

Answer 1

IIRC:

• visitor_id is NULL when it is a customer, thus customer_id is not NULL.
• customer_id is NULL when it is not a logged in customer, thus visitor_id is not NULL.

The case where both are NULL is not an easy one.

The vistor_id is retrieved from the Mage_Log_Model_Visitor class.

The only possibility that comes to my mind is that it is a visitor that has an excluded user agent, which means that is a bot (like Google Bot).

As you can see from the constructor, the request logging is skipped in that case:

protected function _construct()
{
    $this->_init('log/visitor');
    $userAgent = $this->_httpHelper->getHttpUserAgent();
    $ignoreAgents = $this->_config->getNode('global/ignore_user_agents');
    if ($ignoreAgents) {
        $ignoreAgents = $ignoreAgents->asArray();
        if (in_array($userAgent, $ignoreAgents)) {
            $this->_skipRequestLogging = true;
        }
    }
    if ($this->_logCondition->isLogDisabled()) {
        $this->_skipRequestLogging = true;
    }
}

The ignored user agents are defined under app/code/core/Mage/Log/etc/config.xml and are the following:

• Googlebot/1.0 ([email protected] http://googlebot.com/)
• Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)
• Googlebot/2.1 (+http://www.googlebot.com/bot.html)

Finally, the case where both are not NULL

From what I understood, it happens in the following case:

• logged out customer visits a product page
• leaves the website
• comes back and logs in as a customer
• revisits the same product page

In that case, Magento will keep both values.

The visitor data is later set to NULL when the customer logs out with the following code:

public function purgeVisitorByCustomer(Mage_Reports_Model_Product_Index_Abstract $object)
{
    /**
     * Do nothing if customer not logged in
     */
    if (!$object->getCustomerId()) {
        return $this;
    }

    $bind   = array('visitor_id'      => null);
    $where  = array('customer_id = ?' => (int)$object->getCustomerId());
    $this->_getWriteAdapter()->update($this->getMainTable(), $bind, $where);

    return $this;
}