im a osx-dev noob that is trying to build an application with three table views that will show the content of a core data store entity. But each table view is filtered on the attribute "status" of the entity.
the problem occurs when i also want to show the selected entity in textfields. I'm using three different array controllers with different fetch predicates. But in a textfield i can only bind the value to one array controller.
should i ditch the bindings and do it all programaticly or is there a simple solution to this? :)
here is an screenshot so you can grasp my app description.
Keep bindings to populate the text fields if it satisfies what you want to do with this GUI. I'd add an NSObjectController to control the one entity those fields represent. If you want the user's changes to those fields persisted, bindings are still awesome.
But I think with three tables that might control what's displayed in the text fields, you're going to need to have some sort of non-binding glue code that determines which of the tables wins. You can probably do everything you want by implementing some of the NSTableViewDelegate protocol.
If the text fields should display the last entity that the user clicked in any of the tables, simply have each table call the same tableViewSelectionDidChange delegate function. All three tables could have the same delegate. You can then call setContent on the NSObjectController from that function.
You could also use similar glue code to prevent more than one selection in any of the three tables, by having the same delegate function deselect everything in the other tables either through the view or the controller. But that's up to you and needs consideration of whether you want multiple selection, etc.
Related
(I'm using Prism Dryloc) My application consists of two views. The first contains a single list view displaying strings and the second - an entry and a button.
The listview is bound to an observable collection in the first page's View Model. How can I add to the observable collection from a different view?
Great question! You're essentially trying to pass data between views, and there's several ways of passing data between Views in Xamarin.Forms.
The two ways that seem relevant for your case:
Either making the ObservableCollection a public static object (so there's only one global instance of it). Not recommended.
The better way is to use the messaging center so that the second page publishes an event when the button is pressed, that the first page is subscribed to. And it passes that information that gets added to the list.
If these don't work, elaborate your use case and I'll suggest some more
I'm attempting to use Cocoa bindings to populate an NSTableView using Core Data entities. I've arrived at a point where I'm boggled by the behavior of my application. The array controller is in "Entity Name" mode and is using the my "Song" entity.
The table view I am attempting to load the data into has two columns: one for the song name and another for the artist name (the artist is another entity which has a relationship to a song). Through Interface Builder, I have been able to successfully bind the array controller to the table, and setup bindings for the two columns. However, for some reason, one of the columns' bindings is working perfectly (artist name) while the other is not populating at all (song name).
I have gone through each view in the Document Outline and ensured that both columns are configured in exactly the same manner. I've attached some screenshots below showing the binding setup in Interface Builder.
Binding on the NSTableColumn representing the Song Title
Binding on the NSTextField within the NSTableCellView (the one that is not working)
Binding on the NSTextField for Artist Name (the one that is working)
The final (non-functioning) result
Is there an obvious reason why this approach is not working? Any help would be greatly appreciated. I can also provide any additional information that may be needed to answer this question.
It appears you are using a "view" based NSTableView as opposed to the older "cell" based. Each have a different configuration for bindings. In a view based table view you have to bind the tableview content to the array controllers arrangedObjects (see below), you don't have to deal with the individual column bindings that is for cell based table views.
Your remaining bindings look fine.
Just a wild guess. Since you're speaking of the Song entity.
Can it be that you have to bind the song name to objectValue.song.title?
If 'Artist' isn't just an attribute of the 'Song' entity but an entity itself (which it must likely be if it has a relationship to 'Song') then I think you need to have a separate array controller connected to that column in order for it to work properly.
My question is mostly conceptual about Backbone.js, but I can mock up some code if my question is unclear.
Consider a case where I have 2 sections on a website. A list of items as one view and another view that has a dropdown to select how the list of items should be sorted. Obviously, the list of items is associated with a collection of models that stores the actual data that populates the list. But I'm unsure the best approach for triggering the collection to be sorted differently when the other view's dropdown changes. Should I be changing the actual order of the collection, or just render the view in the order that I want in the view?
Also, is it a good idea to use a model for the dropdown to keep track of the state of the dropdown, and bind the list of items view to that model so that I know when to rerender the list of items?
You could take several roads here. Here's a few:
Use a router. The router would hold your views, or at least the top-level view (cleaner), and your dropdown view would trigger a route change, which would pass the information along to the view. Best if you want clean URLs.
Make a pointer to the list view in the dropdown view. When the dropdown view receives the change event, it explicitly tells the list view to update. (IMO a terrible approach, but listed here for completeness.)
Back everything with models. (Like you suggest in your last question.) The dropdown view would be backed by a model, and the list view could bind to that model's events. (Again, the list view still has to know about the dropdown model—not ideal.)
Make an event manager. When your dropdown recevies a change, you trigger 'sort' and anything that cares can listen to that event. This isn't a trivial solution but isn't overly complex either. Your list view could then register its intent to listen to the sort event with the event manager, thereby abstracting the actual view inside the event manager and away from the dropdown view.
1 & 4 are effectively the same thing, just depending on whether you want a router or not.
Basically my heuristic with these sorts of scenarios is "nothing should know about things it doesn't need to know about." Applied here, that means that your views shouldn't know about each other.
This is the scenario: A Core Data model with an entity which contains a relationship to a second entity. The latter entity contains an attribute which is an image and a second attribute with is a name (NSString).
The GUI is a NSTableView which is bound to a NSArrayController. One column of the table is a NSPopUpButtonCell. It is setup so that it currently contains the names of the second entity. It works well so far.
The problem is that I would like to show the image instead of the name. NSPopUpButtonCell is basically able to show images but I'm not able to setup the proper bindings. Setting the bindings directly in the cell doesn't work and the column binding of the table view doesn't feature an image as binding.
It's a little bit complicated but maybe someone can gibe me a hint!
Thanks in advance,
Thomas
I'm trying to create a Mac OS Core Data application that has an array of parent objects (called Levels) each of which contains a collection of child objects (called Blocks) via a one-to-many relationship. I have a table view successfully controlling the array of levels, and a custom view object that draws the blocks graphically based on positions held in x and y properties of my Block model class. I can add blocks to the currently selected level, remove them, select and move them around in the custom view, and have bound text fields to various other properties of the Block class which I can use to edit those values. All of this information is successfully saved and restored to and from the core data repository with no issues output to the debugger. Wonderful. I've used an NSArrayController for the Levels and another for the Blocks that is bound to the current selection of the Levels array controller, in what I've read is a pretty standard way.
Now, my Block class is actually an abstract class, and what I actually instantiate are various child classes of Block (eg RedBlock, GreenBlock, BlueBlock classes). Each sub-class has a separate set of properties that only apply to that type of block (so RedBlock has a "text" property that none of the others have, BlueBlock has an integer "value" property, etc). I want to create an inspector that will change depending on the type of the Blocks that are currently selected in my custom view. To try this, before I start creating subviews for each type of Bock, I have created a text field that I want to bind to the currently selected RedBlock's "text" property, preferably showing nothing when Blocks of other kinds are selected. This is where I'm stuck. I've added another NSArrayController in Entity mode with RedBlock specified as it's type so I can bind to the "text" property, and tried adding a filter predicate based on the class type. I've also tried various other configurations and bindings, but I'm either getting exceptions, or corrupt values in the text field that I bind to that controller, or other weird bugs and general brokenness.
I've googled around for an example of an inspector that can cope with a heterogenous array of objects (as that's essentially what I'm trying to do) but so far no luck.
So, my question is - am I going about this the right way? Should I be trying to create an NSArrayController that filters the selected items in my Blocks array controller somehow? If so, should that be straightforward or is there some trick that I've missed? If not, what is the best way to do this?
This approach should work, provided you limit the inspector to displaying view which bind to properties which apply to the entire selection. You don't need a second array controller.
To test the simple example, try creating a data set with only blocks, see that your bound control loads without raising exceptions, and that it updates the object correctly.
Once that is working, create separate views for each type, and display and hide them when the selection will change. Again, if you have a heterogenous selection, hide them all.