Allow boolean filters to treat NULL as FALSE

i would like perhaps to have this also as a option for gui.
This would be for sure a simple patch for this patch :)

PS: the patch should be out of views root dir.

Updated i developed one simplehandler for a custom module using this feature and it worked as expected

Query before

SELECT node.nid AS nid,
   custom.field AS custom_field,
   node.title AS node_title,
   node.created AS node_created
 FROM node node 
 LEFT JOIN custom custom ON node.nid = custom.nid
 WHERE custom.field = 0
   ORDER BY node_created DESC

Query after:

SELECT node.nid AS nid,
   custom.field AS custom_field,
   node.title AS node_title,
   node.created AS node_created
 FROM node node 
 LEFT JOIN custom custom ON node.nid = custom.nid
 WHERE (custom.field = 0 OR custom.field IS NULL)
   ORDER BY node_created DESC

i think the difference is easy to see

In definitions, I try to avoid underscores. So it should be 'accept null' rather than 'accept_null'.

I'm trying to decide if I would want a checkbox or not to accept NULL, but I think I'm agreeing that it does not need to be a UI element.

Commited to 2.x and 3.x branches.

This is broken in the released Views code, but is useful for me: I also want to filter on whether a related table field exists or is NULL, so I can filter on the existence of the cross-table link.

The released code tests for the configuration setting with:

if (isset($this->definition['accept_null']))

but then uses the value of the setting without the underscore:

$this->accept_null = (bool) $this->definition['accept null'];

The fix is trivial: remove the underscore from the test string.

The workaround is simply to add both 'accept null' and 'accept_null' if you need this set to TRUE in hook_views_data().

Here is a patch

The same problem occurs when using a negativ argument filter i.e. checking "exclude argument". If there are null values in the column the null rows are regarded as having(!) the excluded value. This is commonly not desired.

The SQL Code is
... WHERE field != 'x' ...

and should be
... WHERE field != 'x' OR field IS NULL

Sorry, but I am not responsible for his ugly SQL behaviour.

After consideration, #11 is separate from this issue, though it's similar. That issue is about arguments, and the patch here is about filters.

#10 committed to all branches.