It seems controllerDidChangeContent: is being called as soon as I create a new managed object in my context. The documentation seems to suggest this method is called only once you save: the context.
This "bug" if it is one, is causing my application to crash because as part of my table view cell, I need to load other managed objects that don't exist at the time of creating the main managed object.
Someone seems to have spotted this too, please check out the following link and I would love to hear your opinions on this: http://openradar.appspot.com/10207615
More information
Although the link I added to this post showcases an example using two NSManagedObjectContext, my application is using one context, but the controllerDidChangeContent: is being messaged none the less as soon as an object is created in the one and only context, and controllerDidChangeContent: is being called a second time when I save: this context. It is to my understanding that this method should only be messaged when the context is saved.
The solution is to avoid dealing with more than one managedObjectContext. If your cell needs to load other managed objects, it should still use the same managed object context as the main managed object.
I have yet to see a use case where it is absolutely unavoidable to use more than one managed object context referring to the same model active at the same time.
Related
For every managed object that is sent via iCloud update, this warning/error is sent to the console:
*** ERROR: this process has called an NSArray-taking method, such as
initWithArray:, and passed in an NSSet object. This is being
worked-around for now, but will soon cause you grief.
My managed objects are Clients and have a one to many relationship with assessments as shown below.
class Client: NSManagedObject {
//other NSManaged vars are here
#NSManaged var assessment: NSOrderedSet
}
Judging by the timing of this error (during ubiquitous updates) and the fact that this is my only use of NSSet objects in my project, I can presume that a function during this update is being passed an NSOrderedSet when its expecting an NSArray.
Turning off iCloud removes the errors.
I found two other folks with a very similar issue:
Using iCloud enabled Core Data NSArray-taking method
Core Data Relation between Objects
However, neither offers any solution to my problem. Everything is working fine right now, however "it will soon cause you grief."
If this isn't resolved here, I'll take this issue up with the apple dev support.
I figured it out how to fix this error after much research. (No help in from the Apple Dev forums).
This is error is caused by the Swift 1.2 upgrade. They encourage you to use their new Set<> class instead of NSSet. The error was a vague way of reinforcing that claim.
Ordering of my data was ultimately handled by my NSFetchedResultsController, so I didn't need the stored data to be ordered. So I set out on a task to change the data type for my one to many relationship from NSOrderedSet to Set.
So I created a new data model, selected my relationship and unchecked "Ordered" in the data model inspector. Then migrated to the new model in the next run. (as shown below)
Once that was done, I changed the data type in my managed object subclass from NSOrderedSet to Set. (or Set). That generated compiler errors that were easy to fix throughout my code.
The new Set class easily converts to an array: Array(mySet)
To insert an object to the set, there's an easy insert method. foo.mySet.insert(objectToInsert).
Side note: Converting my relationship to a Set also fixed some weird ordering issues I was having with my table views and the NSFetchedResultsController.
Then I ran the program, generated data, uninstalled the program. Ran the program again and watch the glorious iCloud data populate without the annoying errors.
Boom. I hope this saves someone out there the 10 hours of turmoil (I tried a lot of different things..) I spent to fix this.
What's the difference? When should I prefer one over another?
And some minor questions related to this:
if I have object data, when is saveObject called?
it looks like garbage collector recycles all my domino handles. I tried to downcast then clone it, but it didn't help (how does it know its still a domino object?). Is there a workaround?
if I create "var tmpVar = new package.TestClass()" from xPages, it gets recycled on update. But if I create java object from bean it stays there. Correct?
Managed beans are exactly that, managed by the XPages runtime. They are created as and when there is a first call to them. Although they have an empty constructor, managed-properties elements in the faces-config allow you to define values (and I believe you can add SSJS code to the faces-config to compute the values).
Object data sources allow you to handle what's created when, and it means they can be scoped to a smaller level than viewScope - to a Panel or Custom Control. The saveObject method is called by a Save All Datasources event. In reality, if you're coding object data sources, you'll code a button and call the relevant method rather than use a simple action.
Java variables can get recycled, but Domino objects are only recycled via two methods. The first is calling recycle() methods, the second is at the end of each request, when the session gets recycled. Because recycle() calls recycle all child elements, everything gets recycled at the end of a request. Which is why you can't store Domino objects in scoped variable or any other persisted object (i.e. a bean). Note that objects like DateTimes, RichTextStyles etc are children of the session, not of any more granular Domino object like a NotesItem or NotesRichTextItem.
var tmpVar = new package.TestClass() will only get persisted beyond the current request if you store tmpVar somewhere. If you're using that code in a crerateObject method, return tmpVar will pass that instance of TestClass into the Data Object.
I go back and forth on pure Managed Beans vs. Data Object. I was using a lot of Data Objects for a while but then ran into some issue with the JSF lifecycle I think that I just couldn't make work. Not sure if a repeat or custom control was involved. So I pretty much have gone back and given up on them for now.
Other then that problem I had I'm not sure there's a ton of difference. I think dataObject can tend to be a little more confusion. Since you can set it on an XPage - but you can change the scope of it to session or application I believe. But if you do then that seems messier and hard to find then making the bean in the faces-config.
I'm not sure about the saveObject part of your question.
You never want to put a pure domino object inside a bean, or scoped variable because they are not serializable and will be tossed by the garbage collector at some point that will likely be most inconvenient to you.
if you just do "var tmpVar = new package.TestClass()" then yeah that will get killed pretty quick because of limited life of that variable. if you want to create an object that way and keep it around longer put it in a true scope: viewScope.put("myObject", tmpVar);
I have a video where I tried to give examples of I think 4 ways to use java Objects. In the blog posting are some really good comments by Tim Tripcony which might give you further information.
http://www.notesin9.com/2013/08/01/notesin9-122-working-with-java-objects-in-xpages/
is there a simple and efficient/fast way to query a managedobjectcontext to get an array of all the managedobjects in the context that have not yet been added to the persistent store?
i ask this because i would like to be able to save nsmanagedobjects that have been added to the MOC only if they conform to certain criteria. basically i want to be able to do this so that if some unexpected event happened before my managed object attributes were properly populated, i can catch this fact and purge the object(s) before saving the context. given the complexity of the navigation possible in the app, i'd like to have a look at the data to be sure they are good before i save.
i suppose i could also do this with some kind of validation rule and a flag field that doesn't get set until i am sure the user has added all the data to the record, but i don't yet know how to implement this...
any help much appreciated.
The insertedObjects method of NSManagedObjectContext
returns the set of objects that have been inserted into the context but not yet saved in a persistent store.
This question covncerns my lack of understanding of how to use the core data undo manager and how to restore a NSManagedObject to its state before editing was done.
I am just learning my way around Core Data. I have my NSManagedObject classes set up with their dynamic accessors. I perform a fetch that returns several NSManagedObject entity results. Content from each of these entity results (first name, last name) get put into a table view, and then the user picks one out of the table for detailed view and then editing.
The detail view controller receives a pointer to the selected NSManagedObject entity. As the user edits the fields, the corresponding property value in the NSManagedObject entity is updated. This seemed like the cleanest way to manage these changes.
Now, rather than committing the changes using save, I want to provide a cancel-editing feature that rolls back to what is in the data base for that entity. I really only want to restore the one entity and not perform the entire refetch.
I tried rollback and I tried NSUndoManager (with beginUndoGrouping and endUndoGrouping), and that is not working. I don't think I understand what rollback is really supposed to do.
But in any case, I still want to restore the property values in just that single entity (taking the lazy approach to only fetch what is needed, which is the one entity) so that my detail view controller can refill its view with the correct information. Right now it is using the NSManagedObject entity values, which contain the edited values, which were cancelled.
I suppose I could just start the edit process by creating a copy of the NSManagedObject. If the cancel-editing button is pressed, I could copy it back into the original. (I might even be able to just replace the original with the copy by moving the pointer. But since the pointer has actually been passed through several objects, I'm not sure how to manage the retain number on the copy.)
Does anyone have any other suggestions?
Thanks
Using rollback should accomplish what you want and I'm not sure what it doesn't. It is probably an implementation detail error.
You can find the specific managed object/s that were updated but not yet saved by calling the context's updatedObjects.
I'm designing my first project using Core Data (for iPhone) and Im having some issues that might be related with my design approach.
I'm doing an application that allows the user to create an Order (let's say for a restaurant).
I'm using the graphic designer to model my persistence object (i.e. OrdeMO). I add MO to the ead of each name to indicate its a Managed Object.
I use XCode to create the Managed Object Class automatically.
I have created some "DAO" classes that allows you to search or create a new object in the Managed Context.
Now to my problem.
I want to create an OrderMO object to store the order the user is creating, BUT I don't want it to be part of the context until the user actually places it.
I tried creating the object with [OrderMO alloc] but the object I get is "incomplete" and when I try to set any of its attribute I get an error.
I'm assuming the problem is that I need to create the order IN the context in order to use it. Is that so?
I have considered various options:
Create the object in the context and the user rollback if the user discards the order. The problem is that the user might save other context object during the process (like his prefs) so this doesn't work. Is there a way to create the object "inside a separate transaction" of sorts?
Create a wrapper object that will hold the same data as the MO, and then only create the MO when the user place the order. The downside of this is that I have to maintain a new class.
Create an attribute in the MO, such as "placed", and use to filter my searches in the context. The problem with this one is that I will end up with "trash" objects in the domain (i.e. unplaced orders) and I will have to do some cleanup from time to time...
Do I have any other choice?
Any suggestion is appreciated.
Thanks (for reading this long post!)
Gonso
You should create the OrderMO object in the managed object context and then delete it if the user decides not to place the order.
If the context is saved before the object is deleted, the "trash" object will be deleted from the persistent store on the next save (if the context wasn't saved, the "trash" object will never be saved to the persistent store).
The flag to determine if the order was placed or not does not have to live in the OrderMO object as you suggest in option 3. It could be in the view controller that is tracking the order(s) that are being edited. And, again, you won't have "trash" objects because they will have been deleted.