I am trying to implement a custom binding on a subclass of UITextField so that the bound value is set when the user is done editing instead of with each keystroke because some interim values are invalid in the viewmodel (for example, while setting 'Age' to '26', a value of '2' is invalid so I'd like to wait to set the value until both digits are there). Something similar to setting UpdateSourceTrigger in xaml. I looked at several examples here:
MvvmCross UITextField custom binding is similar, as is MvvmCross: change update source trigger property of binding on MonoDroid (but for Android). I've also watch N=28 custom binding and looked at the source for MvxUITextFieldTextTargetBinding.
I think I'm close, but my custom binding never gets created and the UITextFields in my app still FireValueChanged with every keystroke.
I created the following Custom Binding:
public class UITextFieldFocusChangedBinding : MvxTargetBinding
{
private bool _subscribed;
private UITextField _view;
public UITextFieldFocusChangedBinding(UITextField target) : base(target)
{
_view = target;
}
public override void SetValue(object value)
{
if (_view == null) return;
_view.Text = (string)value;
}
public override void SubscribeToEvents()
{
var view = _view;
if (view == null)
return;
view.Ended += TextFieldOnEnded;
}
private void TextFieldOnEnded(object sender, EventArgs eventArgs)
{
var view = _view;
if (view == null)
return;
if (!view.IsFirstResponder)
FireValueChanged(view.Text);
_subscribed = true;
}
public override Type TargetType
{
get { return typeof(string); }
}
public override MvxBindingMode DefaultMode
{
get { return MvxBindingMode.TwoWay; }
}
protected override void Dispose(bool isDisposing)
{
if (isDisposing)
{
var view = _view;
if (view != null && _subscribed)
{
view.Ended -= TextFieldOnEnded;
_subscribed = false;
}
}
base.Dispose(isDisposing);
}
}
My setup.cs contains the following:
protected override void FillTargetFactories(IMvxTargetBindingFactoryRegistry registry)
{
base.FillTargetFactories(registry);
registry.RegisterPropertyInfoBindingFactory(typeof(Bindings.UITextFieldFocusChangedBinding),typeof(UITextField), "Text");
}
and in my MvxViewController I have:
var set = this.CreateBindingSet<LifeNeedsView, LifeNeedsViewModel>();
set.Bind(_txtFinMedExpenses).To(vm => vm.FinalMedicalExpenses);
set.Apply();
The bindings work (values are passing correctly) but with every keystroke. Any suggestions on what I might be missing?
Related
Trying to do some tests with a ViewPager.
I want to swipe between tabs, and I don't want to continue until the swipe is complete. But there doesn't appear to be a way to turn off the animation for the view pager (all animations under the developer options are disabled).
So this always results in a test failure, because the view pager hasn't completed it's animation, and so the view is not completely displayed yet:
// swipe left
onView(withId(R.id.viewpager)).check(matches(isDisplayed())).perform(swipeLeft());
// check to ensure that the next tab is completely visible.
onView(withId(R.id.next_tab)).check(matches(isCompletelyDisplayed()));
Is there an elegant or maybe even recommended way to do this, or am I stuck putting some kind of timed wait in there?
The IdlingResource #Simas suggests is actually pretty simple to implement:
public class ViewPagerIdlingResource implements IdlingResource {
private final String mName;
private boolean mIdle = true; // Default to idle since we can't query the scroll state.
private ResourceCallback mResourceCallback;
public ViewPagerIdlingResource(ViewPager viewPager, String name) {
viewPager.addOnPageChangeListener(new ViewPagerListener());
mName = name;
}
#Override
public String getName() {
return mName;
}
#Override
public boolean isIdleNow() {
return mIdle;
}
#Override
public void registerIdleTransitionCallback(ResourceCallback resourceCallback) {
mResourceCallback = resourceCallback;
}
private class ViewPagerListener extends ViewPager.SimpleOnPageChangeListener {
#Override
public void onPageScrollStateChanged(int state) {
mIdle = (state == ViewPager.SCROLL_STATE_IDLE
// Treat dragging as idle, or Espresso will block itself when swiping.
|| state == ViewPager.SCROLL_STATE_DRAGGING);
if (mIdle && mResourceCallback != null) {
mResourceCallback.onTransitionToIdle();
}
}
}
}
Since I've done this at least twice now, here is the accepted answer in Kotlin and with androidx ViewPager2:
class ViewPager2IdlingResource(viewPager: ViewPager2, name: String) : IdlingResource {
private val name: String
private var isIdle = true // Default to idle since we can't query the scroll state.
private var resourceCallback: IdlingResource.ResourceCallback? = null
init {
viewPager.registerOnPageChangeCallback(object : ViewPager2.OnPageChangeCallback() {
override fun onPageScrollStateChanged(state: Int) {
isIdle = (state == ViewPager.SCROLL_STATE_IDLE // Treat dragging as idle, or Espresso will block itself when swiping.
|| state == ViewPager.SCROLL_STATE_DRAGGING)
if (isIdle && resourceCallback != null) {
resourceCallback!!.onTransitionToIdle()
}
}
})
this.name = name
}
override fun getName(): String {
return name
}
override fun isIdleNow(): Boolean {
return isIdle
}
override fun registerIdleTransitionCallback(resourceCallback: IdlingResource.ResourceCallback) {
this.resourceCallback = resourceCallback
}
}
And here is how you use it from a UI test using ActivityScenarioRule:
#get:Rule
val testRule = ActivityScenarioRule(OnboardingActivity::class.java)
private lateinit var viewPager2IdlingResource: ViewPager2IdlingResource
....
#Before
fun setUp() {
testRule.scenario.onActivity {
viewPager2IdlingResource =
ViewPager2IdlingResource(it.findViewById(R.id.onboarding_view_pager), "viewPagerIdlingResource")
IdlingRegistry.getInstance().register(viewPager2IdlingResource)
}
}
#After
fun tearDown() {
IdlingRegistry.getInstance().unregister(viewPager2IdlingResource)
}
The androidx.test.espresso:espresso-core library offers a ViewPagerActions class which contains a number of methods for scrolling between the pages of a ViewPager. It takes care of waiting until the scroll is complete so you don't need to add any explicit waits or sleeps in your test methods.
If you need to perform similar scrolling on a ViewPager2 instance, you can take the source code of the ViewPagerActions class and make some minor tweaks to it to get it to work for ViewPager2. Here is an example which you are welcome to take and use.
Try this,
onView(withId(R.id.pager)).perform(pagerSwipeRight()).perform(pagerSwipeLeft());
private GeneralSwipeAction pagerSwipeRight(){
return new GeneralSwipeAction(Swipe.SLOW, GeneralLocation.CENTER_LEFT,
GeneralLocation.CENTER_RIGHT, Press.FINGER);
}
private GeneralSwipeAction pagerSwipeLeft(){
return new GeneralSwipeAction(Swipe.SLOW, GeneralLocation.CENTER_RIGHT,
GeneralLocation.CENTER_LEFT, Press.FINGER);
}
I was having issues with #vaughandroid approach, so I did some changes to his approach. This approach will set idle to false as soon as it detects a scrolling is happening and "force" the ViewPager to finish scrolling by using setCurrentItem().
public class ViewPagerIdlingResource implements IdlingResource {
private volatile boolean mIdle = true; // Default to idle since we can't query the scroll state.
private ResourceCallback mResourceCallback;
private ViewPager mViewPager;
public static ViewPagerIdlingResource waitViewPagerSwipe(ViewPager viewPager) {
return new ViewPagerIdlingResource(viewPager);
}
private ViewPagerIdlingResource(ViewPager viewPager) {
mViewPager = viewPager;
mViewPager.addOnPageChangeListener(new ViewPagerListener());
}
#Override
public String getName() {
return ViewPagerIdlingResource.class.getSimpleName();
}
#Override
public boolean isIdleNow() {
return mIdle;
}
#Override
public void registerIdleTransitionCallback(ResourceCallback resourceCallback) {
mResourceCallback = resourceCallback;
}
private class ViewPagerListener extends ViewPager.SimpleOnPageChangeListener {
float mPositionOffset = 0.0f;
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
if (isSwipingToRight(positionOffset)) {
mIdle = false;
mViewPager.setCurrentItem(position + 1);
} else if (isSwipingToLeft(positionOffset)) {
mIdle = false;
mViewPager.setCurrentItem(position - 1);
}
mPositionOffset = positionOffset;
if (positionOffset == 0 && !mIdle && mResourceCallback != null) {
mResourceCallback.onTransitionToIdle();
mIdle = true;
mPositionOffset = 0.0f;
}
}
private boolean isSwipingToRight(float positionOffset) {
return mPositionOffset != 0.0f && positionOffset > mPositionOffset && mIdle;
}
private boolean isSwipingToLeft(float positionOffset) {
return mPositionOffset != 0.0f && positionOffset < mPositionOffset && mIdle;
}
}
}
My goal was to make a screenshot of the screen with ViewPager2 using Facebook screenshot test library. The easiest approach for me was to check almost every frame whether animation completed, if yes then it's time to make a screenshot:
fun waitForViewPagerAnimation(parentView: View) {
if (parentView is ViewGroup) {
parentView.childrenViews<ViewPager2>().forEach {
while (it.scrollState != ViewPager2.SCROLL_STATE_IDLE) {
Thread.sleep(16)
}
}
}
}
childrenViews function can be found here
You can either do a lot of work and use an IdlingResource to implement an OnPageChangeListener
or simply:
SystemClock.sleep(500);
I am working with an attached behavior for logging user actions on a ScrollBar.
my code:
class ScrollBarLogBehavior : Behavior<ScrollBar>
{
protected override void OnAttached()
{
base.OnAttached();
AssociatedObject.Loaded += new RoutedEventHandler(AssociatedObject_Loaded);
}
void AssociatedObject_Loaded(object sender, RoutedEventArgs e)
{
...
var track = (Track)AssociatedObject.Template.FindName("PART_Track", AssociatedObject);
// ** HERE is the problem: track is null ! **
...
}
How can I detect that the template has loaded and I can find the Track?
(when I call AssociatedObject.Template.LoadContent() the result containt the requested Track, so it i a matter of timing and not a matter of wrong template or naming)
Override the method OnApplyTemplate
public override void OnApplyTemplate()
{
base.OnApplyTemplate();
var textBox = Template.FindName("PART_Textbox", this) as TextBox;
}
I did not find any good way to detect when the template was loaded. However, I did find a way to find the Track:
in OnAttached() - register to Scroll event fo the ScrollBar (this can only happen after the entire template is loaded, of course):
protected override void OnAttached()
{
base.OnAttached();
_scrollHandler = new ScrollEventHandler(AssociatedObject_Scroll);
AssociatedObject.AddHandler(ScrollBar.ScrollEvent, _scrollHandler, true);
}
When handling the Scroll event, remove registration and find the Thumb:
void AssociatedObject_Scroll(object sender, ScrollEventArgs e)
{
var track = (Track)AssociatedObject.Template.FindName("PART_Track", Associated
if (track == null)
return;
AssociatedObject.RemoveHandler(ScrollBar.ScrollEvent, _scrollHandler);
// do my work with Track
...
}
If I understand correctly, you wish to create an attached behavior that will reference a template part after the ScrollBar has been loaded.
The following should work:
internal static class ScrollBarLogBehavior
{
public static readonly DependencyProperty LogUserActionProperty = DependencyProperty.RegisterAttached(
"LogUserAction",
typeof(bool),
typeof(ScrollBarLogBehavior),
new UIPropertyMetadata(default(bool), LogUserActionChanged));
public static bool GetLogUserAction(DependencyObject obj)
{
return (bool)obj.GetValue(LogUserActionProperty);
}
public static void SetLogUserAction(DependencyObject obj, bool value)
{
obj.SetValue(LogUserActionProperty, value);
}
public static void LogUserActionChanged(DependencyObject s, DependencyPropertyChangedEventArgs e)
{
if (s is ScrollBar scrollBar)
{
scrollBar.Loaded += OnScrollBarLoaded;
}
}
private static void OnScrollBarLoaded(object sender, RoutedEventArgs e)
{
if (sender is ScrollBar scrollBar)
{
if (scrollBar.Template != null)
{
// I'm not sure, but the `name` in the following method call might be case sensitive.
if (scrollBar.Template.FindName("PART_Track", scrollBar) is Track track)
{
// do work with `track` here
}
}
}
}
}
where you would "attach" the behavior in your XAML with:
<ScrollBar guiControls:ScrollBarLogBehavior.LogUserAction="True">
<!-- more here -->
</ScrollBar>
BE ADVISED: this implementation completely ignores the bool value that is being set for LogUserAction
I am developing an app for iOS using MvvmCross. On one of my Views I have some basic report data that is displayed in a tableview.
When the table row is touched a new view containing a detail report is displayed by making the call to ShowViewModel passing some parameters in a Dictionary. This works fine.
When the user swipes left or right the app needs to show the detail report for the next or previous item in the original list. I am doing this by updating some parameters and calling ShowViewModel again. The logic behind this is all working fine.
My problem; ShowViewModel animates the new view coming in from the right. This is perfect when the user has swiped left. However when swiping right it seems counter intuitive. How can I make ShowViewModel animate or transition in from the left side?
if you look to the MvvmCross source code here you see how the default behavior is showing the ViewControllers
You need to change that by doing something like the following:
How to change the Push and Pop animations in a navigation based app
for that, one idea is to have a custom view presenter and catch navigation to that particular view-model (override Show(IMvxTouchView view) )
or, maybe derive from UINavigationController, set it to MvvmCross to use it (look to the MvxSetup), and on some events change transition to that particular view
similar to this question
How to specify view transitions on iPhone
This is the solution I was able to come up with following the helpful pointers in the answer from Andrei N. In the end I opted for a TransitionFlipFromRight and TransitionFlipFromLeft when scrolling between detail reports. Hopefully it is useful to somebody else.
I already had a presenter class that was inherited from MvxModalSupportTouchViewPresenter
public class BedfordViewPresenter : MvxModalSupportTouchViewPresenter
Within this class I added a property of MvxPresentationHint.
private MvxPresentationHint _presentationHint;
In the override of method ChangePresentation the above property is used to store the passed in parameter
public override void ChangePresentation (MvxPresentationHint hint)
{
_presentationHint = hint;
base.ChangePresentation (hint);
}
Two new MvxPresentationHint class were declared (see later)
In the presenter class the Show method was overridden
public override void Show(IMvxTouchView view)
{
if (_presentationHint is FlipFromRightPresentationHint) {
var viewController = view as UIViewController;
MasterNavigationController.PushControllerWithTransition (viewController, UIViewAnimationOptions.TransitionFlipFromRight);
}
else
if (_presentationHint is FlipFromLeftPresentationHint) {
var viewController = view as UIViewController;
MasterNavigationController.PushControllerWithTransition (viewController, UIViewAnimationOptions.TransitionFlipFromLeft);
}
else {
base.Show (view);
}
_presentationHint = null;
}
A new class that provides extensions to a UINavigationController was created with the method PushControllerWithTransition
public static class UINavigationControllerExtensions
{
public static void PushControllerWithTransition(this UINavigationController
target, UIViewController controllerToPush,
UIViewAnimationOptions transition)
{
UIView.Transition(target.View, 0.75d, transition, delegate() {
target.PushViewController(controllerToPush, false);
}, null);
}
}
All that needs to be defined now are the two new MvxPresentationHint class derivations. These belong in your Core class library project rather than the iOS application project.
public class FlipFromLeftPresentationHint : MvxPresentationHint
{
public FlipFromLeftPresentationHint ()
{
}
}
and
public class FlipFromRightPresentationHint: MvxPresentationHint
{
public FlipFromRightPresentationHint ()
{
}
}
I hope this is a help to someone else trying to do something similar
Share my solution for android:
On view:
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
var view = base.OnCreateView(inflater, container, savedInstanceState);
var layout = view.FindViewById<LinearLayout>(Resource.Id.swippeable);
var swipeListener = new SwipeListener(this.Activity);
swipeListener.OnSwipeLeft += (sender, e) => this.ViewModel.LeftCommand?.Execute(); //Here use command into view model
swipeListener.OnSwipeRight += (sender, e) => this.ViewModel.RightCommand?.Execute();
layout.SetOnTouchListener(swipeListener);
return view;
}
Gesture listener:
public class SwipeListener : SimpleOnGestureListener, View.IOnTouchListener
{
private const int SWIPE_THRESHOLD = 100;
private const int SWIPE_VELOCITY_THRESHOLD = 100;
private readonly GestureDetector gestureDetector;
public SwipeListener(Context ctx)
{
this.gestureDetector = new GestureDetector(ctx, this);
}
public Boolean OnTouch(View v, MotionEvent e)
{
return this.gestureDetector.OnTouchEvent(e);
}
public event EventHandler OnSwipeRight;
public event EventHandler OnSwipeLeft;
public event EventHandler OnSwipeTop;
public event EventHandler OnSwipeBottom;
public override Boolean OnDown(MotionEvent e)
{
return true;
}
public override Boolean OnFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY)
{
Boolean result = false;
float diffY = e2.GetY() - e1.GetY();
float diffX = e2.GetX() - e1.GetX();
if (Math.Abs(diffX) > Math.Abs(diffY))
{
if (Math.Abs(diffX) > SWIPE_THRESHOLD && Math.Abs(velocityX) > SWIPE_VELOCITY_THRESHOLD)
{
if (diffX > 0)
{
SwipeRight();
}
else
{
SwipeLeft();
}
result = true;
}
}
else if (Math.Abs(diffY) > SWIPE_THRESHOLD && Math.Abs(velocityY) > SWIPE_VELOCITY_THRESHOLD)
{
if (diffY > 0)
{
SwipeBottom();
}
else
{
SwipeTop();
}
result = true;
}
return result;
}
public void SwipeRight()
{
this.OnSwipeRight?.Invoke(this, EventArgs.Empty);
}
public void SwipeLeft()
{
this.OnSwipeLeft?.Invoke(this, EventArgs.Empty);
}
public void SwipeTop()
{
this.OnSwipeTop?.Invoke(this, EventArgs.Empty);
}
public void SwipeBottom()
{
this.OnSwipeBottom?.Invoke(this, EventArgs.Empty);
}
}
The card.io component (http://components.xamarin.com/view/cardioios) has a fallback screen that has a Cancel and a Done button on them.
Neither of which actually do anything. I assume it is up to me to subscribe to and event, however, there is no event to subscribe to.
Here is the code:
var paymentDelegate = new PaymentViewControllerDelegate();
var paymentViewController = new Card.IO.PaymentViewController(paymentDelegate);
paymentDelegate.OnScanCompleted += (viewController, cardInfo) =>
{
viewController.DismissViewController(true, null);
if (cardInfo == null)
{
}
else
{
new UIAlertView("Card Scanned!", cardInfo.CardNumber, null, "OK", null).Show();
}
};
paymentViewController.AppToken = "app-token";
// Display the card.io interface
base.PresentViewController(paymentViewController, true, () => { });
There is a method on the PaymentViewControllerDelegate, but I can't figure out what to do with it:
public override void UserDidCancel(PaymentViewController paymentViewController);
public override void UserDidProvideCreditCardInfo(CreditCardInfo cardInfo, PaymentViewController paymentViewController);
I guess the problem is that the Component doesn't expose any events for the Fallback View.
You need to subclass PaymentViewControllerDelegate:
public class MyPaymentDelegate : PaymentViewControllerDelegate
{
public MyPaymentDelegate ()
{
}
public override void UserDidCancel (PaymentViewController paymentViewController)
{
// Implement on-cancel logic here...
base.UserDidCancel (paymentViewController);
}
public override void UserDidProvideCreditCardInfo (CreditCardInfo cardInfo, PaymentViewController paymentViewController)
{
// Implement logic for credit card info provided here...
base.UserDidProvideCreditCardInfo (cardInfo, paymentViewController);
}
}
And then provide an instance of this class into the constructor for Card.IO.PaymentViewController:
var paymentDelegate = new MyPaymentDelegate();
var paymentViewController = new Card.IO.PaymentViewController(paymentDelegate);
So, I figured this out by looking at the working sample application and comparing it to what I had done.
All I had to do was widen the scope of the paymentDelegate and paymentViewController variables.
If you look at the sample, you really just need to subscribe to the OnScanCompleted event which is called in both cases of UserDidCancel (where cardInfo will be null), and UserDidProvideCreditCardInfo (where it will not be null).
In fact, this is the code for the binding, so you can see the Event was made as a 'helper' to make it so you didn't have to make your own delegate implementation:
namespace Card.IO
{
public partial class PaymentViewControllerDelegate : BasePaymentViewControllerDelegate
{
public delegate void ScanCompleted(PaymentViewController viewController, CreditCardInfo cardInfo);
public event ScanCompleted OnScanCompleted;
public override void UserDidCancel (PaymentViewController paymentViewController)
{
var evt = OnScanCompleted;
if (evt != null)
evt(paymentViewController, null);
}
public override void UserDidProvideCreditCardInfo (CreditCardInfo cardInfo, PaymentViewController paymentViewController)
{
var evt = OnScanCompleted;
if (evt != null)
evt(paymentViewController, cardInfo);
}
}
}
If you still really want to implement the delegate yourself, subclass BasePaymentViewController instead, however I don't think you really need to make your own subclass of it...
Hopefully that helps!
I'm rolling my own ActivatableCollection<T> for db4o but cribbing heavily from the builtin ActivatableList<T> implementation. I'm running into the problem where transparent persistence doesn't seem to be working correctly. In the test code below:
[Fact]
void CanStoreActivatableCollection()
{
var planets = new ActivatableCollection<Planet>();
var pagingMemoryStorage = new PagingMemoryStorage();
var config = Db4oEmbedded.NewConfiguration();
config.Common.Add(new TransparentActivationSupport());
config.Common.Add(new TransparentPersistenceSupport());
config.File.Storage = pagingMemoryStorage;
var objectContainer = Db4oEmbedded.OpenFile(config, "Memory.yap");
planets.Add(new Planet("Mercury"));
objectContainer.Store(planets);
planets.Add(new Planet("Venus"));
planets.Add(new Planet("Earth"));
objectContainer.Commit();
objectContainer.Close();
config = Db4oEmbedded.NewConfiguration();
config.Common.Add(new TransparentActivationSupport());
config.Common.Add(new TransparentPersistenceSupport());
config.File.Storage = pagingMemoryStorage;
objectContainer = Db4oEmbedded.OpenFile(config, "Memory.yap");
planets = objectContainer.Query<ActivatableCollection<Planet>>().FirstOrDefault();
Assert.NotNull(planets);
Assert.Equal(3, planets.Count);
objectContainer.Close();
}
The planet "Mercury" is stored, but not "Venus" and "Earth". If I change from ActivatableCollection to ActivatableList, then all 3 planets are stored.
What am I missing? My ActivatableCollection is just minimal implementation of ActivatableList as best as I can tell.
Below is my implementation of ActivatableCollection:
public class ActivatableCollection<T>
: ICollection<T>
, IActivatable
, INotifyCollectionChanged
{
List<T> _list;
List<T> List
{
get
{
if (_list == null)
_list = new List<T>();
return _list;
}
}
public ActivatableCollection()
{
}
public int Count
{
get
{
ActivateForRead();
return List.Count;
}
}
public bool IsReadOnly
{
get
{
ActivateForRead();
return ((IList) List).IsReadOnly;
}
}
public void Add(T t)
{
ActivateForWrite();
List.Add(t);
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, t));
}
public void Clear()
{
ActivateForWrite();
List.Clear();
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
}
public bool Contains(T t)
{
ActivateForRead();
return List.Contains(t);
}
public void CopyTo(T[] array, int index)
{
ActivateForRead();
List.CopyTo(array, index);
}
public IEnumerator<T> GetEnumerator()
{
ActivateForRead();
return List.GetEnumerator();
}
IEnumerator IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
public bool Remove(T t)
{
ActivateForWrite();
bool removed = List.Remove(t);
if (removed)
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, t));
return removed;
}
[Transient]
private IActivator _activator;
public virtual void Bind(IActivator activator)
{
if (_activator == activator)
return;
if (activator != null && _activator != null)
throw new InvalidOperationException();
_activator = activator;
}
public virtual void Activate(ActivationPurpose purpose)
{
if (_activator == null)
return;
_activator.Activate(purpose);
}
protected virtual void ActivateForRead()
{
Activate(ActivationPurpose.Read);
}
protected virtual void ActivateForWrite()
{
Activate(ActivationPurpose.Write);
}
[Transient]
public event NotifyCollectionChangedEventHandler CollectionChanged;
protected virtual void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
{
if (CollectionChanged != null)
CollectionChanged(this, e);
}
}
I've also tried copying the code from GenericTypeHandlerPredicate and registering my ActivatableCollection to use the GenericCollectionTypeHandler. That results in a crash in GenericTypeFor() throwing an InvalidOperationException() when "Mercury" is being stored.
Just want to mention my answers from the db4o forums also here, for people with a similar problem:
First part of the issue:
From db4o's point of view nothing has changed in the 'ActivatableCollection' object and therefore no changes are stored. This is what is happening:
When you add the items, the ActivatableCollection is marked as changed.
When you commit the changes are stored. However the ' ActivatableCollection' holds the reference to the same object. db4o only stores the changes in the ActivatableCollection-object, which is the reference to the List. Since it is the same, no actual change is stored.
The List of the ActivatableCollection is never updated, because it wasn't marked as 'changed'
So the transparent activation doesn't see the changes in the list. You can fix your issue simply by using an ActivatableList in you're ActivatableCollection implementation. Just change the List with a IList interface and instantiate a ActivatableList instead of an List.
The second part of the issue: Why doesn't it work even when registering the GenericCollectionTypeHandler for this type? Here we hit a implementation detail. The GenericCollectionTypeHandler has an internal list of supported types, which doesn't include the self made 'ActivatableCollection'. GenericCollectionTypeHandler is not really part of the public API and intendet for internal use only.
Workaround / Fix
Just use an ActivatableList<T> instead of a List<T>. then everything works fine.