i have a core-data app with an entity that has
hostname
username
password
(all NSString) for attributes.
Then I'v linked up the core data model, the array controller, and table view with add and remove buttons.
Basically, at this stage I have written about zero lines of code and the app works great.
(This is simple version of Chapter 11 from Cocoa Programming for Mac OS X, Hillegass)
The question is how do I (programmatically) get the selected entity/object as seen in the tableView from managedObjectContext or the array controller?
You use the NSArrayController's selectedObjectsmethod. That returns an array of the objects whose data was selected in the UI. You can bind to it or call the method directly.
Related
This question already has answers here:
Automapper: Update property values without creating a new object
(4 answers)
Closed 4 years ago.
Is there any way to use Automapper 5.1.1 to update an existing object as opposed to creating a new one.
For example we have a Customer entity and a CustomerViewModel. We would like to update an existing Customer with the CustomerViewModel field values.
Would greatly appreciate your assistance.
It is not adviced to use Automapper to map a model to your Entity. Dependencies or Informations can be overwritten if it isn't used wisely.
But to use it as you want, you only need to create a map from your Model to your Entity and then call
Mapper.Map(myModel, myEntity);
The mapping to entity Problem
I guess you use a ORM like NHibernate or EF, then your Entites are Proxies, where references are proxies too and so on. Now lets imagine you have an ASP.NET MVC Project and you map your Entity to your ViewModel. You show your Model in your View as a form, but you only show the properties that you need in your view, not all that are set in your ViewModel. Then the user sends the Form back to you and your Controller gets the ViewModel back, but this time not all Properties are set, because your View only knew the ones that were shown. If you map your ViewModel back to your entity, all unitialized properties are in there default state and will overwrite the valid data f rom your entity.
Another Problem is, that AutoMapper uses Reflections to set the Properties. Normally the right to exist for an ORM is the possibility to easy implement an DomainLayer. The DomainLayer has some Validations, Calculation... on the Entity itself. If now the Properties set with Reflection it would ignore the Business logic and no Validation, Calculations.... would be executed.
So my advice is, Don't map to Entities ;)
I have two windows, one is a table view to display content. One is a window for inputting content.
I have an NSTextField binded to a property in my app delegate. When I change a value in the text field, the app delegate property will change. However, if I go the other way and programmatically change the property's binded key, the value of the text field does not update. However, it does in the table view.
What is going wrong here? How can I update text field?
EDIT:
I tried all 3 of these with the same result
[_addEntry setValue:#"Chet" forKey:#"payee"];
[_addEntry setPayee:#"chet"];
_addEntry.payee = #"chet";
EDIT:
Here's a simple example to elaborate on my point
https://dl.dropboxusercontent.com/u/48014761/test.zip
the label and the textfield are bound to the "str" property. It is initially null. press log to see that in the console. press change str button to change the string. Log to verify. Note that the label and the textfield do not update!
EDIT:
"What am I trying to accomplish?"
Here's the project I am working with:
https://dl.dropboxusercontent.com/u/48014761/Write-Offs.zip
I am trying to use Cocoa Bindings as much as possible. I have a table with a bunch of data. However, each entry is going to have an array of images associated with it. Thus, when I add a new entry, I need to open up a new window so I can set the properties of that entry (rather than through the table) along with upload some images.
I am not sure I am implementing the addEntryWindow correctly. It seems like I should create and destroy the window each time I open and close it. This doesn't appear to be happening.
Also, [[self addEntry] setDate:[NSDate date]]; doesn't seem to fix the problem for me.
Thanks
Chet
How are you programmatically changing the field? Are you using KVO? Is the field inside of a NSManagedObject instance?
Bindings work through KVO. Core Data disables some aspects of KVO for its own internal uses and you might be tripping over one of those.
Update your question with the code sample and lets see what is going on.
Update
Both windows don't necessarily need to be in the same xib but they do need to be talking to the same instances. Ideally they should both be talking to the same instance of NSManagedObject and therefore talking to the same NSManagedObjectContext.
Who is the owner of each window?
Is the owner the same?
If not, is a new Core Data stack being created?
Update
In your test, I was able to correct it by how you were editing the property
- (IBAction)press:(id)sender {
[self setStr:#"this"];
}
You were accessing the iVar directly instead of the property. When you access the iVar directly KVO does not fire.
In addition, in your xib files you were accessing self.str which is unnecessary. It should be just str.
Are you doing any direct property access in your actual project?
Update
You can do a get accessor and then a set accessor:
[[self addEntry] setPayee:xxx];
Based on the variables you are using I wonder what you are trying to accomplish. Can you post the exact code of the programmatic change you are trying to enact?
I am having a very hard time understanding what needs to be included in the Children Views in order to perform a fetch request and display the results in a table view when using Core Data. All the examples I have found are either only one layer deep (Random Dates), using the Root View Controller which always works, or using several view controllers with pictures and other attributes (Recipes) that make it confusing for me to follow.
An example of what I am looking for would be an Entity with three attributes. The entity is album and the three attributes are albumTitle, albumArtist and yearRecorded.
Now in my Navigation app my Root View Controller has three rows to choose from not using the Entity or Core Data at all. The three choices are "Title", "Artist" and "Year". When you click on one of the three rows it will push a new view controller and list all of the appropriate attributes in a new table view.
I believe it should be very simple and not require too much code but I can't get a handle on it. Any explanations or sample code is greatly appreciated.
You could just make a fetch request with no predicates to get all the objects from your Core Data store, so, you'll have an array of songs.
Than you just call, for example, [fetchedSongs valueForKeyPath:#"artist"]; to get an arry of artist and add it as a source to your tableview.
I have 2 forms and the data should be stored in the record store only after filling all the fields in both the forms and if we switch from one form to another the fields in the form should contain whatever the user has entered. So how do I store the previous data and auto populate it when he switches from one form to another?
You need to indicate whether you are actually using LWUIT manually to build the form or using the GUI builder. Also the answer for 1.4 differs from the answer to 1.5.
If you are using LWUIT 1.5 just use LWUIT4IO's Storage classe's writeObject method. Create an object that implements the com.sun.lwuit.io.Externalizable interface and contains your data. You will need to register it using the LWUIT4IO Util class.
There is a sample for serializing data within the Tipster demo in LWUIT, it stores hardcoded and modified data into storage.
If you are using 1.4 just go over the RMS API. Not the most intuitive API in the world but usable for storing data.
You can get the values from RecordStore and populate that values into another Form. Look on the following article for how to read/write/update the record's into RecordStore.
J2ME record management system
Update record's in record store
RMS basics
you can have one public DataObject Class.
Now Create getter & setter public method in it and access them from anywhere in the project.
The issue
I have a popup button (NSPopUpButton) that is bound to an NSArrayController. This array controller handles parent objects that each have a collection of child objects. I have an NSTableView in which I need to show these children for the selected item in popup. In addition, the list of children needs to be manipulated (add/remove).
I've tried to accomplish this in many ways but always run into some thing that complicates the solution. What is the best way to implement this?
The data is managed here by Core Data and thus, the collections are NSSets. I've tried adding a conversion method in the parent to return a sorted NSArray (in order to bind it with NSArrayController) but this approach prevents the KVO and the array controller is not updated properly.
Thank you in advance.
An example
To clarify, here's a hypothetic example:
Let's say I have a list of countries that is maintained elsewhere. One of these countries is selected in a popup button. Each country has a set of cities. When a country is selected a table view is populated by it's cities.
There is a solution for this without the delegate/datasource setup.
My context is this:
CoreData model with Parents and Children, one Parent has multiple Children via a relationship named children. Both have a attribute name.
The two Entities must be available as classes (each with a .m and a .h). (Xcode will write them for you if you go to File-New-File-CoreData-NSManagedObjectSubclass.) Now the ChildObjects of a ParentObject can be accessed by ParentObject.children
Two NSArrayControllers: ParentArrayController and ChildArrayController.
Two NSTableViews: ParentTable and ChildTable, each with one column for name. (It should not matter whether you use a Popup or a table as long as it's controlled by a NSArrayController.)
The steps to take are as follows:
Connect both NSArrayControllers to the MangagedObjectContext as usual and set them to Mode: Entity Name with their respective Entity (Parent or Child)
Bind both TableViews (their columns) to their NSArrayController as usual.
Now comes the magic: In the ChildArrayControllers binding section under ControllerContent-ContentSet bind to the ParentArrayController with ControllerKey: selection and ModelKeyPath: children.
Done. If you select a ParentObject in the ParentTable the ChildTable shows its children.
To add and remove children to parents you can use the (void)addChildrenObject:(Child *)value; method that Xcode wrote for you in the Parents.m class file.
I didn't find any way to implement this by simply with dragging and dropping. I had to implement a delegate and data source for the table of cities (from the example). The window controller is notified of the selection changes in the popup button and this updates the content on the table view delegate / data source.
I actually feel this is little bit better way to implement the issue (than with bindings and array controllers) since it gives more control over special cases.