I am using MVC 5 and Visual Studio 2013.
In my HTML I am using
#model namespace.Models.UserViewModel
and my UserViewModel is a model class defined like this.
I have also my Gender class defined like this, where I fill my SexList with Male and Female genders.
What I want to do is to add a radio button for each option in my list.
So in my HTML I add
But in runtime have an error saying
Model.SexList is empty.
My question is how can I fill my list before using it?
The question you posted itself is wrong.
The code where you do
List<Gender> lista = null;
lista.Add(new Gender { ID =1, Type = "Male"});
// ^^ this line gives you run time error as object does not have a instance.
You need to create an instance of the object and then add the items into it
List<Gender> lista = new List<Gender>();
With this change your code is good to exhibit the desired behavior unless you have changed the contents of the SexList else where before the for loop, Which you have not posted in your question.
For what you have posted it seems like you have forgot to instantiate your list.
You should have a lista = new List<Gender>(), as you haven´t instantiate it you should be getting exception trying to add new elements to the list.
Other alternative you could to is to place to SexList initialization in the class constructor:
public UserViewModel()
{
SexList = new List<Gender>();
SexList.Add...
}
Or make it (the SexyList property) static already initializing it.
Regards,
You need to fill SexList in the User object like below
foreach (var user in users)
{
user.SexList=new SexList(){}
}
Related
I have two datatemplates. One is the default and the other one is for when the user selects this item. I need to give the selected item double width and height of the normal template. How can I do this?
What you want to do is not difficult, but it is not solved by swapping the data template. Instead, it is accomplished by using Visual States in XAML. A Visual State allows you to create multiple "views" of your XAML (for example, what it looks like when it is selected and when it is not selected) and to switch between those easily. Swapping data templates is a big deal, Mostafa, and can result in your UI flickering because the underlying subsystem has to re-render so many parts of the visual tree.
If you want to learn more about the Visual States, you might read over the blog article I wrote on the same subject.
http://blog.jerrynixon.com/2013/11/windows-81-how-to-use-visual-states-in.html
The only problem now is to figure out how to trigger the visual state when the item in a gridview or listview is selected. First, you should know that IsSelected is a property on the gridviewitem or listviewitem control that houses your item. However, it's tricky to reach that property and the most common approach is to sub-class your gridview/listview and override PrepareContainerForItemOverride and set the binding in code-behind.
Like this:
class MyModel
{
public bool IsSelected { get; set; }
}
class MyList : Windows.UI.Xaml.Controls.ListView
{
protected override void PrepareContainerForItemOverride(DependencyObject element, object item)
{
var model = item as MyModel;
var listViewItem = element as Windows.UI.Xaml.Controls.ListViewItem;
var binding = new Windows.UI.Xaml.Data.Binding
{
Source = model,
Mode = Windows.UI.Xaml.Data.BindingMode.TwoWay,
Path = new PropertyPath(nameof(model.IsSelected)),
};
listViewItem.SetBinding(Windows.UI.Xaml.Controls.ListViewItem.IsSelectedProperty, binding);
base.PrepareContainerForItemOverride(element, item);
}
}
I hope this helps.
Best of luck!
i cant figure out this one so maby you guys can help me out.
i store some data in the form of a array filled with Objects in this example cards.
in my main class i have the following code:
deckSprite.savedData = SharedObject.getLocal("cardsdata");
deckSprite.savedData.data.savedArray = deckSprite.deckArr;
deckSprite.savedData.flush();
trace(deckSprite.savedData.data.savedArray);
the trace will output something like [object card1, object card2, object card3]
now in a static class called "deckSprite" i have this:
savedData = sharedObject.getLocal("cardsdata");
if (savedData.data.savedArray == undefined)
{
trace("no save yet");
}
{
else
{
trace("save loaded");
deckArr = savedData.data.savedArray;
trace(savedData.data.savedArray);
now my trace data turns out only ", ," (somehow the cards are gone).
now after i got saved data i restart my application and whenever he tryes to acces the deckArr it crashes giving me the error "A term is undefined and has no properties".
how is it possible that when i save the array it saves all the cards inside the array and when i restart the application its suddenly only ",,"but the cards are gone?
When serializing objects in AS3, you have to register their class using registerClassAlias() from package flash.net. So you have to call something like
registerClassAlias('com.example.deck', Deck)
in the program before any saving or loading happens.
See full reference at AS3 API Reference
NOTE: As pointed out by #BadFeelingAboutThis in comments, you have to register all referenced class in your Deck, i.e. if your deck looks like this:
class Deck {
var firstCard:Card;
var type:DeckType;
}
to be able to save Deck to SharedObject you have to call
registerClassAlias('com.example.deck', Deck);
registerClassAlias('com.example.card', Card);
registerClassAlias('com.example.decktype', DeckType);
before any saving/loading is done.
EDIT
Everything depends on content of your array
If I assume, your deckSprite is declared like this:
var deck1:Deck = new Deck();
var deck2:Deck = new Deck();
var deckArr:Array = new Array(deck1, deck2);
var deckSprite:DeckSprite = new DeckSprite()
deckSprite.setDeckArr(deckArr);
then before adding deckArray to SharedObject, you have to call registerClassAlias(). Sou your save code will look like this:
registerClassAlias('com.example.deck', Deck);
deckSprite.savedData = SharedObject.getLocal("cardsdata");
deckSprite.savedData.data.savedArray = deckSprite.deckArr;
deckSprite.savedData.flush();
trace(deckSprite.savedData.data.savedArray);
(replace the Deck with actual class you use for representing your decks)
Similarly the first line has to be called before you do any loading.
Of course it is best not to repeat yourself, so you should call registerClassAlias('com.example.deck', Deck); only once in your program, so for example in some init() method in your main class, if you have something like that.
In the N+1 video #34 (Progress), there was an example of using CreateBindingSet() for the Android version, which is not typical. But the narrator also mentioned briefly that the same can be done on the Windows platform.
As much as I tried, however, I am unable to get a View's property to be bound to its ModelView on the Windows Phone. I always get a NullReferenceException.
The closest I came was the code below, including suggestions from ReSharper. Here's my FirstView.xaml.cs:
using Cirrious.MvvmCross.Binding.BindingContext;
using Whatever.ViewModels;
namespace Whatever {
// inheriting from IMvxBindingContextOwner was suggested by ReSharper also
public partial class FirstView : BaseView, IMvxBindingContextOwner {
public class MyBindableMediaElement
{
private string _theMediaSource = "whatever";
public string TheMediaSource
{
get
{
return _theMediaSource;
}
set
{
_theMediaSource = value;
}
}
}
public FirstView()
{
InitializeComponent();
_mediaElement = new MyBindableMediaElement(this.theMediaElement);
var set = this.CreateBindingSet<FirstView, FirstViewModel>();
// the corresponding view model has a .SongToPlay property with get/set defined
set.Bind(_mediaElement).For(v => v.TheMediaSource).To(vm => vm.SongToPlay);
set.Apply();
}
public IMvxBindingContext BindingContext { get; set; } // this was suggested by ReSharper
}
I get a NullReferenceException in MvxBaseFluentBindingDescription.cs as soon as the view is created. The exact location is below:
protected static string TargetPropertyName(Expression<Func<TTarget, object>> targetPropertyPath)
{
var parser = MvxBindingSingletonCache.Instance.PropertyExpressionParser; // <----- exception here**
var targetPropertyName = parser.Parse(targetPropertyPath).Print();
return targetPropertyName;
}
I have not seen a working example of creating a binding set on a Windows Phone emulator. Has anyone gotten this to work? Thanks.
I can confirm that the narrator said that remark a little too flippantly without actually thinking about how he might do it...
However, with a little effort, you definitely can get the CreateBindingSet to work in Windows if you want to.
Before you start, do consider some alternatives - in particular, I suspect most people will use either Windows DependencyProperty binding or some hand-crafted code-behind with a PropertyChanged event subscription.
If you do want to add CreateBindingSet code to a Windows project then:
Add the Binding and BindingEx assemblies to your Ui project - the easiest way to do this is using nuget to add the BindingEx package.
In your Setup class, override InitializeLastChance and use this opportunity to create a MvxWindowsBindingBuilder instance and to call DoRegistration on that builder. Both these first two steps are covered in the n=35 Tibet binding video - and it's this second step that will initialise the binding framework and help you get past your current 'NullReferenceException' (for the code, see BindMe.Store/Setup.cs)
In your view, you'll need to implement the IMvxBindingContextOwner interface and you'll need to ensure the binding context gets created. You should be able to do this as simply as BindingContext = new MvxBindingContext();
In your view, you'll need to make sure the binding context is given the same DataContext (view model) as the windows DataContext. For a Phone Page, the easiest way to do this is probably just to add BindingContext.DataContext = this.ViewModel; to the end of your phone page's OnNavigatedTo method. Both steps 3 and 4 could go in your BaseView if you intend to use Mvx Binding in other classes too.
With this done, you should be able to use the CreateBindingSet code - although do make sure that all binding is done after the new MvxBindingContext() has been created.
I've not got a windows machine with me right now so I'm afraid this answer code comes untested - please do post again if it does or doesn't work.
I can confirm it works almost perfectly; the only problem is, there are no defaults register, so one has to do the full binding like:
set.Bind(PageText).For(c => c.Text).To(vm => vm.Contents.PageText).OneTime();
to fix this, instead of registering MvxWindowsBindingBuilder, I am registering the following class. Note: I have just created this class, and needs testing.
public class UpdatedMvxWindowsBindingBuilder : MvxWindowsBindingBuilder
{
protected override void FillDefaultBindingNames(IMvxBindingNameRegistry registry)
{
base.FillDefaultBindingNames(registry);
registry.AddOrOverwrite(typeof(Button), "Command");
registry.AddOrOverwrite(typeof(HyperlinkButton), "Command");
//registry.AddOrOverwrite(typeof(UIBarButtonItem), "Clicked");
//registry.AddOrOverwrite(typeof(UISearchBar), "Text");
//registry.AddOrOverwrite(typeof(UITextField), "Text");
registry.AddOrOverwrite(typeof(TextBlock), "Text");
//registry.AddOrOverwrite(typeof(UILabel), "Text");
//registry.AddOrOverwrite(typeof(MvxCollectionViewSource), "ItemsSource");
//registry.AddOrOverwrite(typeof(MvxTableViewSource), "ItemsSource");
//registry.AddOrOverwrite(typeof(MvxImageView), "ImageUrl");
//registry.AddOrOverwrite(typeof(UIImageView), "Image");
//registry.AddOrOverwrite(typeof(UIDatePicker), "Date");
//registry.AddOrOverwrite(typeof(UISlider), "Value");
//registry.AddOrOverwrite(typeof(UISwitch), "On");
//registry.AddOrOverwrite(typeof(UIProgressView), "Progress");
//registry.AddOrOverwrite(typeof(IMvxImageHelper<UIImage>), "ImageUrl");
//registry.AddOrOverwrite(typeof(MvxImageViewLoader), "ImageUrl");
//if (_fillBindingNamesAction != null)
// _fillBindingNamesAction(registry);
}
}
This is a skeleton from Touch binding, and so far I have only updated three controls to test out (Button, HyperButton and TextBlock)
A question about ItemRenderers: let's say I have an ArrayCollection that is my application data sitting inside a global object. I them populate a sparks list with this data, setting the ArrayCollection as the dataProvider.
So each ItemRenderer gets a copy of an item sitting in the array. You can override the "set data" method to set the data something more domain-specific. The problem is that the data is a copy of the original item.
Now let's say we want to add some data to the item while inside the ItemRender. For example, it could call a method on the item telling it to load some details about itself, or maybe we allow the user to modify something on the item.
Obviously, we can't do any of this if we are operating on a copy because it will be thrown away as soon as the ItemRenderer is destroyed and the original object doesn't know anything about what happened.
So what's the best practice? Should I just use the itemIndex of the renderer to pull out the original item from my global array like this:
{globalArrayCollection}.getItemAt(this.itemIndex)
But it seems kind of clunky to me. Is there a best practice for dealing with this?
Not sure I'm following but it sounds like you're looking for a way to get at your item renderer to set/change a value.
You could go about accessing a method on the renderer directly.
In your renderer:
public function setSomeValue(aValue:String):void{
someString = aValue;
}
You would also set the data on your ArrayCollection as well.
To access this method you would use this:
var dataGroup:DataGroup = list.dataGroup;
var itemRenderer:YourItemRenderer = dataGroup.getElementAt(list.selectedIndex) as YourItemRenderer;
itemRenderer.setSomeValue("string");
Hmm, why do you think that original ArrayCollection won't change if you change values in itemRenderer? For me this works and initial ArrayCollection changes.
[Bindable]
protected var model:Model;
override public function set data(value:Object):void
{
super.data = value;
this.model = value as Model;
}
protected function changeValue():void
{
model.value = "newValue";
}
Or am I misunderstood something?
I am using a s:TextInput in Flex 4.5. It shows it's prompt text if the underlying text value is null or empty String. Does anybody know if I can make either don't show the prompt on empty String or even show a different prompt?
I already found a way by extending the TextInput class and overriding some of the methods but I am still hoping anyone here knows an easier way ;-)
Ok, so based on the comments, here it is:
You store the current prompt value in a private variable, like so:
private var _inputPrompt:String = "";
Then you create a getter, so the value is accessible from outside of this class:
public function get inputPrompt():String
{
return _inputPrompt;
}
Now you can bind inputPrompt anywhere you need it, however, the problem is the getter won't be recalled once the private value changes. You can fix this very easily: Create an update method, for example like so:
public function updateInputPrompt(value:String):void
{
_inputPrompt = value;
}
Ok, nothing fancy so far. I'm guessing this is the point where you are right now. In order to "force" the getter to be recalled, you have to bind it to an event, like so:
[Bindable(event="inputPromptUpdated")]
public function get inputPrompt():String
{
return _inputPrompt;
}
Finally, you can simply dispatch this event when the value is update (i.e. in the updateInputPrompt method):
public function updateInputPrompt(value:String):void
{
_inputPrompt = value;
dispatchEvent("inputPromptUpdated"); // For binding
}
This way, the getter will be recalled every time you dispatch that event.
Hope this helps. Have a great day, and a great weekend!