Cocoa-Binding : Submit changes manually?

Question

Hello

in my application I have a NSTableView bound to an ArrayController (arrangedObjects). I also have a Details-View (just some textfields) bound to the same Controller (selection).

Now every time I edit a textfield the changes are automatically send to the ArrayController and the Table changes as well. How can I avoid this? What I want is a "Submit-Button". Changes on the data should only be send to the controller when I press the button and not automatically every time I do an edit.

Answer 1

There are really two answers to this question. The first is more philosophical: in most cases you want updates to the model to occur instantaneously. For the most part users shouldn't have to be bothered with saving, committing, etc. changes the make. Binding's pervasive integration with the NSUndoManager means that anything the user does can be undone (or should be undoable). All user actions should be "low risk" such that making a change and then undoing does not cause unnecessary "harm" to the user's data or the application state. If you're using Core Data for your model layer, you can always roll-back or save a set of changes programmatically using the NSManagedObjectContext's methods. Unless there's a really good reason why the user needs a "Submit" button, don't put one in. In line with this philosophy is Gmail's "Undo Send" functionality. Even sending an email should be undoable (within reason).

The second answer is more practical. Of course there are situations where you're dealing with a backend system that isn't as forgiving of undos as Cocoa. In that case, the best option is to create a temporary model object that serves as the model for the UI (think a View-Model in the Model-View-View-Model (MVVM) architectore). When the user submits the changes, you can copy the temporary model object into the persistent model. In Core Data, you can use an in-memory persistent store backing a separate managed object context to hold these temporary instances and then merge changes from this temporary context into your main context on submit.

Answer 2

This might be enough:

• Select the text fields in Interface Builder.
• Switch to the "Text Field Attributes" pane of the Inspector panel (hit Cmd-1).
• Change the Action popup box to "Sent On Enter Only".