I am writing a Master-Detail program in XCode, and want to add the ability to save all the data the user has put in. Currently I have an assignmentArray (NSMutableArray) in my controller object that is bound to an NSArrayController. When clicking a button, it should add an instance of my model object to the array. This appears to work fine. However, when I try to save it, the array is empty. As far as I have seen from debugging, the array is always empty. Why is it not containing these objects?
I followed this tutorial and my code doesn't have any errors or warnings.
The problem was that I bound the ArrayController to the model object instead of File's Owner. Changing this fixed the problem.
Make sure you have bound your ArrayController to File's Owner and not an instant of your controller!
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We are creating a Sportsbook web app using Emberjs, where we retrieve data through an API and draw the view.
The received data is an object with many nested levels. Based on this object we have constructed the template file(.hbs) using each-in helper!
We are unable to use 'each' helper as we are receiving object, not array!
After the first retrieval, we are receiving updates every milliseconds and need to update the view as well by changing only the difference.
Sometimes we are receiving new entries in the object, and as the object itself is big, we need to add the new entry to the layout without redrawing the whole stuff.
Here is the problem: Each-in is not observable in this case, so it is not redrawing after pushing the new object.
Question: Is there a good way to implement this with Ember or is there a known helper that we can use instead of each-in, OR is there someone who can recommend me if we CAN create a new helper for this?
I passed the result of this.store.findAll('something') to a component so I could create a dropdown control. Everything works great but I'd like to find the object I selected by reading this property.
Everything I read says its bad practice to inject the store into these components and since I already have the data in the property I thought it would be easy to read. However it's in an Ember model array that doesn't seem to be so easy to open because the array is deep down the stack.
I started heading down something like this.get('myprop').content... but I wondered if this was the correct way to do this. It seems I should be able to open them as the model they should be.
Any suggestions would be helpful.
it turns out the best way I could find to select my model was the 'peek' function. Not exactly what I wanted to do but it works.
Some of the comments below my initial question also work, but nobody ever actually added an answer so this is my answer. :-)
I have some questions about what can I do with dynamic objects qml. I have to create a "many logs viewer" so in a window I've to create many TableViews as logFiles does the user have. I know how to create them dynamically but after the creation I have to add a logFile info and refresh it everytime a the file its modificated, basically when a new record arrives. The important question is can I add an Id to every dynamic TableView to add information at each model. Maybe on each component I'll have to add a combo to select wich file I want to view. this is why I need an Id or something to know wich object I'm going to point. actually I have to resize and reorder the components depending of how many windows does the user want to see. Its there a way to solve it ??
The problem is that you cannot assign id property to dynamically created object. This property managed by QML engine and associate with object while parsing. So you have to use objectName to refer to dynamic object or store pointer to object, returned by Component.createObject()
I am displaying a list of Document titles on the site's sidebar area. To achieve this I created a documents property on the App.SidebarController
Document = require '../models/document'
SidebarController = Ember.Controller.extend
documents: (->
Document.find()
).property()
module.exports = SidebarController
This works fine, when I create a new Document in my application, this sidebar property get's updated automatically and I don't know why. It works no matter what I put in the .property() function. e.g.
.property('Document')
.property('App.Document')
Can somebody explain how this works? What would be the correct thing for the property() function to observe?
So you are basically saying that is works, but you would like to know why.
Here is my guess: When your controller gets rendered, your computed property gets computed for the first time and an instance of an array is returned. When you create a new Document, i think this very same array is updated (= Document is added). So it does work despite the fact, that you do not specify a dependent key on property(). This is because the right array is already in place. As i said just a guess, but this seems like an understandable explanation.
And what would be the correct thing to do?
IMHO one should not use such Data Access methods directly in a computed property. Instead you should call this Data Access method inside a Route and then assign it to the controller. This way you make sure, that the find() method gets executed when needed.
I'm running into a performance issue when I render a list of items using the #each helper or a collection view bound to some computed properties of an Ember.ArrayController. Performance is fine with a small list of 10 - 20 items, but around 50 - 100 it starts to lag quite noticeably. Try checking off a few todos or clicking "Add Todo"
Example code is here: http://jsfiddle.net/Jonesy/ed3ZS/4/
I noticed that the childViews in the DOM get re-rendered with each change, which could very well be the intended behaviour at the moment, but I'd prefer to be able to just have a todo be removed from the DOM of unfinished todos list individually and appended to the bottom of the finished todos list, which would in theory be much less costly.
What I'm hoping to have answered is whether am I looking at a performance issue with Ember collection views, or is displaying a list populated from a computed property a bad idea, and if so, will I need to manually manage the todo model's location in the view layer as it changes from unfinished to finished and vice versa.
This is a side-effect of how {{#each}} (and CollectionView, which is what powers it) works.
Internally, CollectionView uses something called array observers. An array observer allows you to subscribe to mutations made to an array when they are done using Ember.Array's mutation methods (replace, pushObject, popObject, etc.) The API for array observers is described here.
What this means is that, if you push a new object into a collection view, it will insert render one new element in the DOM and leave the rest in place.
In the example you posted, however, the array is not being mutated--you're creating a brand new Array object every time a new item is added or removed. When the binding synchronizes, it replaces the old array with the new array. To {{#each}}, this is no different than removing all of the elements and then adding them back in.
The solution to the problem is to use a single array, instead of a computed property that returns a different array object each time it changes. You can see the Contacts app for an example of how to do this.
Obviously this is a very common pattern, and we'd like to add some kind of filtering that does the right thing by default to Ember.ArrayController down the road.