I really hope someone can help on this because I'm learning cocoa and have hit a road block.
I am trying to model a simple poker tournament. For now, my entities are simply a Tournament (with a number) and a Player (with a Name). A Tournament has an array of Players.
I can bind two independent table views to display the tournaments and the players just fine. But I want the players table view to just show the players that belong to the selected tournament from the first table view.
Each has it's own array controller. I have tried a variety of different bindings for the second (players) table but to no avail. Has anyone accomplished this? If so maybe you could spell it out for me, as I there are few examples online.
Update
I can now ALMOST get where I need to, mostly through rial and error and hours of googling. I have bound the player AC's content to the tournament AC, with controller key 'selected objects' and Model Key Path 'players', which is the name of the array in my Tournament entity.
I have the bound the column in the players table view to this second Player AC, controller key arranged objects. But what to put in the Model Key Path? I know it is working because if I stick #count in there I get the correct number of players for the selected tournament. But 'name' and 'player.name' are no good. Is there any kind of 'item.name' or 'players.item.name' I can try?
Sooo close, thanks for the help so far:
I think this tutorial will help you. They also create a master/detail view.
In short: Bind the contentArray of your player's array controller to the tournament's array controller, set ControllerKey to selection and the remaining properties accordingly to your model.
I found the answer here:
Implementing parent->child drill down in Cocoa with Core Data bindings that span multiple entities.
The child controller needs to know about the managedObjectContext through its own binding.
The child controller must not be in Entity Mode, but rather operate as a NSMutableDictionary class.
And, finally, the child controller does not prepare its data. It retrieves it from the parent, through the Content Set binding. Use the controller key selection, and the model key path that connects to the children.
I'm surprised this is not a more commonly used practice, and hope the next person reading this doesn't spend so long finding the answer!
Related
I've read up and done the tutorials for Joomla 3. Here is my problem:
My requirement is more complex than the HelloWorld one. I have multiple tables, on the admin side, to maintain (entries - add, update and delete). Thus it means multiple controllers, views and models (one for each database table)
To explain:
Lets say I have 2 tables in the database; shop and area. The default view is for shop. I've created MVCs called shop and shops - working. Then I created MVCs called area and areas. The areas one works to show a list of the areas in the DB.
The area view works (display the right form, but no data) but there is something wrong with the model; when I look at MyCompViewArea Object's item member, item, it still have the array for shop.
I'm stuck, can you point me to a comprehensive tutorial that covers this?
Ok, silly me!
One gets blind to one's code. I've kept on hunting for the problem and because of another question ask (Fatal error: Call to a member function getKeyName()) I took a closer look at my table class and found that the class name was wrong. It was MyCompTableMyComp instead of MyCompTableArea
I'm creating an application in which I have several entities and now I need to filter the content of third combobox dynamically. I explain myself better. I have 3 combobox (building, floor and department), I would like first to show me all the buildings included, but the second should show only selected before the plans for the building, the last I should be select only the departments of the building and the plan you choose. How can I do this? To simplify attaching some photos.
You simply drill down with predicates, if you use single fetch requests to Core Data.
However, your relationships are not set up correctly. For example, there is an edificio attribute in Particelle. If it refers to an building, it should be a relationship to a Edifici object, not some kind of foreign key. There are no foreign keys in Core Data, just relationships.
If you do this, everything becomes much easier by using a NSFetchedResultsController. You can now simply traverse the object graph without any specific fetching.
The scheme could be something like this (maybe need to change the order):
Anno <--->> Particella <---->> Edificio <---->> AreaRischio
Now you can simply tell the fetched results controller to start fetching all Anno entities. Then you drill down with simple dot notation:
NSSet *listForNextTable = selectedAnnoObject.particelle;
and further with
NSSet *listForNextTable = selectedParticellaObject.edifici;
etc. You see, it gets really simple.
I have a working system that lets me build a database containing instances of various entities , all linked together nicely.
Before I knew I would care, I came across a tutorial on using Core Data and bindings, and it went through a complete case where you get a table showing all the entities of some type with a column for each property. It showed both the UI side and the Data model side - not that I need the data model part at this point. Now, darned if I can find it. This is one of those things that is supposed to be easy, and requires virtually no code, but getting exactly the right connections in UIBuilder is not going to happen if I can't find instructions.
Also, I thought I came across an example of something like a query editor where the user could select which properties to sort on, which to match on, etc. Did I imagine that?
Anyone out there know where I can find such?
Sure, you can do this without code:
Add an array controller to your nib.
Bind or connect an outlet for its managed object context
Set the array controller to Entity mode, fill in the entity name, and select Prepares Content.
Bind your table view columns to array controller's arranged objects, and fill in the key name for the model key.
Regarding the query editor, open up the model, and on the Editor menu click Add Fetch Request.
I found at least a partial answer to the query editor question, in this apple tutorial. Not sure how far it will get me, as I prefer to write code where possible, since then I can leave a trail of comments.
Here's the scenario. There are two CoreData model objects, A and B, and the relationship between them is that A has-many B, represented by the property setOfBs. I'd like to display two tables, one listing all the As (Table 1), another listing all the Bs (Table 2). As the user selects items in Table 1, the selection in Table 2 changes to reflect the value of setOfBs of the A selected in Table 1. The content of the table doesn't change, only the selection changes. And if the selection in Table 1 changes, it would change the setOfBs to reflect that.
Can this be accomplished using bindings? Or would custom logic be required?
I believe you will have to write additional logic to get this approach to work. Here's why: The selection bindings for NSArrayControllers (and all the UI objects that bind to them) are based on selection indexes but when you have an object of type A, it vends a set of B objects. Assuming you have an array controller for As and an array controller for Bs, you need a way to get from those objects to their indexes in the array of Bs in order to set the selection of the array controller for B. This isn't hard code to write, but I don't believe you'll be able to do this with bindings alone.
That said, as you speculated in your comment, this doesn't seem like a good way to edit this relationship. In the common case, TableView selection is UI state, and not model state. If you build a UI like you describe, UI state and model state become the same thing. I'm not saying it's impossible, or inherently bad, but it's not really a "standard" way to do this sort of thing. One common pattern looks like this:
Even an approach like this will require additional logic, because there appears to not be a way (out of the box) to bind to "All Bs not in the selected A's setOfBs" without writing code. Again, not difficult code to write, but it's not clear to me that this can be done with bindings alone. I could be wrong, but that's my reading of the situation.
I'm making a custom view that I want to be bindings/core data compatible and represent a collection of data (a la NSTableView)
Is there any way my view can refer to a specific subset of the elements in the collection (other than the current selection) after a change by the user?
A bit of context:
The view is going to display a number of user-moveable boxes in a 2D space. Each box corresponds to a record in the model. Several can be moved at once, and I can't rely on the delta value being the same for each box (so no adding a delta to each selected object).
I guess I'm looking for something like an id assigned to each element of the content array by NSArrayController, so that the view can associate that id with each box. My first thought was to use the the index in a content array, but this could be messed up by undo/redo. I could subclass NSArrayController and get it to auto-generate an id for each model item, but does cocoa already do something like this already? Feels like I might be missing something.
I should have mentioned that I originally tried keeping each of the content array's elements stored in the view (as Peter suggests), but had them stored as keys in an dictionary.
The objects in the view didn't match the keys in the dictionary, so I assumed this meant that NSArrayController changed the proxy objects it uses to stand for model objects.
However, it turned out that NSDictionary copies its keys, so it seems to be no good for situations where you want to associate a particular instance of an object with another.
NSMapTable is its more flexible cousin, and can be configured not to copy its keys.
Why not just refer to the objects themselves? You can keep them in a set or array, whichever is appropriate.
If you really need an identifier of some sort: What for? What are you going to do with it?