Re: NSPredicateEditor

FROM : Peter Ammon
DATE : Thu Jan 24 23:23:12 2008

On Jan 24, 2008, at 12:47 PM, Kimo wrote:

>
> On Jan 7, 2008, at 4:08 PM, Peter Ammon wrote:

>>
>> On Jan 7, 2008, at 3:34 PM, Kimo wrote:
>>

>>> I'm using the NSPredicateEditor template in IB, and it works 
>>> well.  The exception is with a BOOL value.  For example, if I 
>>> have a BOOL value called flag, and I want to use the string (flag 
>>> == 1), however, using the NSPredicateEditor always produces the 
>>> string (flag == "1") which doesn't work.  Is there an option to 
>>> create the string without the quotes?  Or is there some setting 
>>> in NSPredicateEditor I'm not aware of?
>>> TIA.

>>
>> Hi Kimo,
>>
>> If you want to have the boolean option be represented by a text 
>> field, you can of course just select the Numbers type for the 
>> right expression.  That will coerce the right expressions to a 
>> numeric type and give you a string like flag == 1.
>>
>> If (more likely) you want the boolean value to be represented by a 
>> popup, this can't yet be configured in IB, but it is easy to do 
>> programmatically.  Create an NSPredicateEditorRowTemplate with 
>> left expressions your key path expressions, and right expressions 
>> as constant expressions containing your boolean values.  Then you 
>> can configure the view titles and all the rest by modifying the 
>> templateViews.
>>
>> Let me know if you have any questions,
>> -Peter
>>

>
> Hi Peter,
>
> That helped a lot, thank you.  I have another question.  I created 
> (programmatically) a NSPredicateEditorRowTemplate so that the left 
> popup button has "Start Date" and "End Date."  The middle popup 
> button has "is today" and "is the date" and "is before the date." 
> The right expression is a NSDatePicker.  However, when the user 
> selects the operator "is today" I want the NSDatePicker to be 
> hidden, and then visible for the other two operators.
>
> I see other apps do this (Mail for example), but I can't seem to 
> accomplish the same thing.  I subclassed 
> NSPredicateEditorRowTemplate so I could alter the templateViews, 
> but I can't seem to determine which middle popup is selected.  What 
> is the best way to hide the NSDatePicker when the user selects the 
> menu item "is today" and then displays it for the other menu items?


Hi Kimo,

The right way to do this is to create two row templates.  From its 
templateViews method, the first one should return two views, like this:
[Start Date / End Date] [is today]

While the second one should return three  views, like this:
[Start Date / End Date] [is the date / is before the date] 
_DATE_PICKER_

(By [Start Date / End Date], I mean that view should be a popup 
button with two items titled respectively Start Date and End  Date).

NSPredicateEditor will notice the identical titles in the initial 
popups of both templates, merge them together, and correctly show or 
hide the date picker based on what is selected in the second popup.

Hope that helps,
-Peter