Checkbox Fields (Boolean) Force Defaults In _Search Form

I ran into a problem when using a check box field on a record mapped to a boolean column.

In the _search form, if the user never touches the check box field, the field will then default to it’s database default value.

The checkbox forces a "Yes" or "No" into the CGridView filter when the "search" button is pressed.

When not using Advanced Search (ie "_search" form)

the CGridView filter fields have the option of being null if you don’t select them.

The search function must set them, but I don’t understand how.

Is there an option to control this? I have looked at the function

and have not found anything that seems to allow the control over this behaviour.

Thanks for any advice !

I believe my only options may be to use something other than a checkbox, such as a drop down list that can pass a null

but if the table default is being read into the record, even this may not help.

I have the same problem, how did you solve it ?