On Jul 20, 2009, at 22:16, Daniel Child wrote:
I seem to have fallen into the pitfall you described below. I can
get the table view to display values in a combo box from a data
source, which takes those values from an array in the model. I also
have autocomplete working.
But I can't seem to get the values I choose to "stick" (remain
displayed) in the table. Since the tableview is reusing the combo
box cell, I don't see how you specify a different value for each row
(I only have one column). (The choice values do appear when you
click the arrow, but selecting them does not store a value.) Also,
I'm not clear on when you "capture" a selection to get the value
transferred to the model.
Are you supposed to use some notification to know that the field has
been edited, and then capture that value and transfer it to the
model. Sorry if this seems basic, but I've looked over the
documentation and some sample code and just don't get it.
Here's what I'd try:
-- I'd give each data model object a string property "stateName", and
bind the table column to this property.
-- I'd write a "validateStateName:" method to check that the entered
name was one of the names in my list of names. That'd probably a case-
insensitive test, so I'd also use this method to replace the user's
entry with a copy of the actual string from the list. (Make sure you
turn on "validates immediately" for the binding. That means that the
validation is done on Enter or Tab, not on every character typed as
the name of the option might suggest.) Refer to the KVC documentation
for information about how to write a validate<Key>: method.
If the user is allowed to enter names not in the list, then this
method would validate non-list names for correctness (and do things
like apply proper capitalization and replace the user entry with a
prettified string) as desired.
-- I'd write a "setStateName:" setter to store the entered name in the
instance variable backing the "stateName" property. Since this method
could potentially be called for other reasons, I'd also re-apply the
prettification here, so that the resulting value 'isEqualToString:'
the matching string from your master list, if it's in your master list.
That's the general idea. The specifics would depend on whether:
-- the user was *only* allowed to enter things from your master list
-- the user was allowed to enter things not in the master list, which
then get added to the master list
-- the user was allowed to enter arbitrary names, which are *not*
added to the master list if unknown
If you need the model objects to store a property that's the numeric
index into the master list, that can be done in the setter too. One of
the properties would be made dependent on the other, but again the
details depend on what behavior you specifically need to allow.
Note that this implementation (which is part of the data model)
doesn't know that a NSComboxBox is being used to get the name -- a
regular text field could be used just as easily (for you, though not
for the user). That's as it should be.
HTH
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