I want to pass a simple class object from one XAML page to another in a C++ Windows 8 application. I have created a class in App.xaml.h:
ref class StaticInfo sealed {
public:
property Platform::String^ sName;
};
I haved added this to MainPage.xaml to navigate to Page2.xaml:
void StaticApp::MainPage::Button_Click_1(Platform::Object^ sender, Windows::UI::Xaml::RoutedEventArgs^ e)
{
StaticInfo^ StaticData;
StaticData->sName=ClickText->Text;
Frame->Navigate(Page2::typeid,StaticData);
}
And then received the smart pointer in Page2:
void Page2::OnNavigatedTo(NavigationEventArgs^ e)
{
(void) e; // Unused parameter
StaticInfo^ data = (StaticInfo^)e->Parameter;
}
I get this error when I navigate to Page2:
Unhandled exception at 0x003A5EE1 in StaticApp.exe: 0xC0000005: Access violation reading location 0x00000010.
Can anyone tell me the exact way to do it. If possible please provide a link that teaches passing data between pages. What if I want to pass multiple objects of different classes?
You need to actually create the StaticInfo object before you start using it:
StaticInfo^ StaticData = ref new StaticInfo();
StaticData->sName=ClickText->Text;
Related
We have implemented several custom ORM objects in our webshop implementation that have references (dependencies) to Intershop Product system object.
When a user tries to delete a certain product in back-office, it causes problems because references to that product may still exist in our custom objects. Naturally, deleting a product that is referenced from one of our custom objects generates an exception like this:
java.sql.SQLTransactionRollbackException: ORA-02091: transaction rolled back ORA-02292: integrity constraint (INTERSHOP.A1POSTPAIDPRICE_CO_002) violated - child record found
We have figured that we could solve that by implementing an ORMObjectListener and overriding objectDeleting method to delete all the references before the product actually gets deleted.
Intershop cookbook for ORM layer states:
"Instances must implement the interface ORMObjectListener for a given ORM object type and register at the factory. The listener is called when instances of the given type are created, changed or removed."
(https://support.intershop.com/kb/index.php/Display/2G3270#Cookbook-ORMLayer-Recipe:NotificationofPersistentObjectChanges)
However, we cannot find a cookbook for registering the listener at the factory. What do we need to do to register the listener?
Also, if there is some better way for handling dependencies to system objects on our custom objects during delete event, I'm open to suggestions.
UPDATE:
This is the listener class I have tried with so far:
public class ProductDeleteListener implements ORMObjectListener<ProductPO> {
#Inject
ProductPOFactory productPOFactory;
/** The Constant LOGGER. */
private static final Logger LOGGER = LoggerFactory.getLogger(ProductDeleteListener.class);
public ProductDeleteListener() {
productPOFactory.addObjectListener(this, new AttributeDescription[0]);
}
#Override
public boolean isOldStateNeeded() {
// TODO Auto-generated method stub
return false;
}
#Override
public void objectChanged(ProductPO object, Map<AttributeDescription, Object> previousValues) {
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("PRODUCT LISTENER TEST - CHANGE");
}
}
#Override
public void objectChanging(ProductPO object, Map<AttributeDescription, Object> previousValues) {
// TODO Auto-generated method stub
}
#Override
public void objectCreated(ProductPO object) {
// TODO Auto-generated method stub
}
#Override
public void objectCreating(ProductPO object) {
// TODO Auto-generated method stub
}
#Override
public void objectDeleted(ORMObjectKey objectKey) {
// TODO Auto-generated method stub
}
#Override
public void objectDeleting(ProductPO object) {
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("PRODUCT LISTENER TEST - PRE DELETE");
}
}
}
But it is not working. Nothing gets logged when object changes or gets deleted.
In addition to what Willem Evertse wrote you need to place your registration code in a class that gets instantiated via Intershop Component Framework.
implementation.component:
<components xmlns="http://www.intershop.de/component/2010" scope="global">
<implementation name="ProductDeleteListenerRegistrar"
class="your.fullqualifed.ProductDeleteRegistrar" start="start" stop="stop"></implementation>
instances.component:
<components xmlns="http://www.intershop.de/component/2010"> <instance name="ORMValidator" with="ORMValidator" scope="global"/></components>
You need to write a class, e.g. ProductDeleteRegistrar and provide start method in which you can add registration calls like Willem described. As for stop method you need to safely unregister your object listener. Make sure both methods are declared to be synchronized.
I think registering a listen would be the right approach. Maybe just look out for performance problems.
You are right that there are no examples of this, but here is an example.
Get the factory that you want to receive messages from. In your case, it is ProductPOFactory
ProductPOFactory productFactory = (ProductPOFactory) NamingMgr.getInstance().lookupFactory(ProductPO.class);
productFactory.addObjectListener(new MyProductChangeListener());
MyProductChangeListener needs to extend AbstractORMObjectListener<ProductPO>
and implement the method public void objectDeleting(T object)
Every time a product gets deleted your listener should be called and then you can clean up your custom orm objects. You can have a look at ImageSetDefinitionPOListener as an example
I'd like to know if there's any difference between static/dynamic binding and early/late binding?
As far as I'm aware, they are basically different ways of referring to the same concepts.
Given a simple hierarchy like this:
class Phone {
...
}
class iPhone extends Phone {
public boolean isExpensive() {
return true;
}
}
class Wileyfox extends Phone {
public boolean isExpensive() {
return false;
}
}
Early/Static binding is when types and which types methods are called upon at compile time:
iPhone phone = new iPhone();
phone.isExpensive();
When calling isExpensive() method here, the compiler already knows that it needs to bind a type iPhone to the phone variable at compile time.
Late/Dynamic binding is when the compiler is not able to figure out who is going to be calling at compile time, but at runtime:
public boolean canAfford(Phone phone) {
return !phone.isExpensive();
}
In this case, the compiler is not able to determine it until the code is actually being run.
I have project that need to reference to some web service, just say my reference is
service1Facade and service2Facade
both of them contain class name objectA
i must load objectA from service1Facade and use it as parameter in service2Facade.
but i got error
"value of type service1Facade.objectA cannot be converted to service2Facade.objectA"
how can i convert these object ?
what i have try but still not work:
group all reference into same folder, but .NET change its name into
objectA and objectA1
I copy every property of the property inside objectA, but still not working.
The functionality that is responsible for generating proxy classes based on your WSDL specification doesn't know (and it shouldn't know) that both your services use the same underlying type for objectA, and as I mentioned, no assumptions can be made regarding this since web services are meant to be decoupled from each other (from the consumer point of view).
I'd say your best option is to have your own proxy class (let's say ServiceProxyDTO) that can be used in both service #1 and #2. Something along the lines of:
public class ServiceProxyDTO
{
// Define properties from "objectA"
public ServiceProxyDTO() { }
public ServiceProxyDTO(service1Facade.ObjectA copyFrom)
{
// Copy state from "copyFrom"
}
public ServiceProxyDTO(service2Facade.ObjectA copyFrom)
{
// Copy state from "copyFrom"
}
public static implicit operator service1Facade.ObjectA(ServiceProxyDTO dto)
{
return new service1Facade.ObjectA() { /* Copy state back */ };
}
public static implicit operator service2Facade.ObjectA(ServiceProxyDTO dto)
{
return new service2Facade.ObjectA() { /* Copy state back */ };
}
public static implicit operator ServiceProxyDTO(service1Facade.ObjectA obj)
{
return new ServiceProxyDTO(obj);
}
public static implicit operator ServiceProxyDTO(service2Facade.ObjectA obj)
{
return new ServiceProxyDTO(obj);
}
}
With this code you can instantiate ServiceProxyDTO and pass it as parameter to both service #1 and #2 (as well as get the return values from both of these services).
Hope this helps.
I'm working on a Windows 8 Store App (using the Grid App Template) and while I'm loading data from a server I want to show a ProgressRing and hide the GridView or ListView (depends on if the app is snapped or not) that will display the data once it is fully loaded.
The issue is that when the ViewModel is loading data I need to be able to change the VisualState.
I found what I thought was a solution Here, but this code will not build.
public class StateManager : DependencyObject
{
public static string GetVisualStateProperty(DependencyObject obj)
{
return (string)obj.GetValue(VisualStatePropertyProperty);
}
public static void SetVisualStateProperty(DependencyObject obj, string value)
{
obj.SetValue(VisualStatePropertyProperty, value);
}
public static readonly DependencyProperty VisualStatePropertyProperty =
DependencyProperty.RegisterAttached(
"VisualStateProperty",
typeof(string),
typeof(StateManager),
new PropertyMetadata((s, e) => //this throws the error
{
var propertyName = (string)e.NewValue;
var ctrl = s as Control;
if (ctrl == null)
throw new InvalidOperationException("This attached property only supports types derived from Control.");
System.Windows.VisualStateManager.GoToState(ctrl, (string)e.NewValue, true);
}));
}
ERROR: Cannot convert lambda expression to type 'object' because it is
not a delegate type
Does anyone know how to get the linked solution to work? Or is there a simpler method that I am completely missing (I'm a XAML newbie!)?
I'm not even sure if the listed solution will work because the "Snapped" vs "Full" states are managed by the base LayoutAwarePage class included with the template.
why not simply use a datatrigger bind to a viewmodel property like IsBusy {get;set;} to enable your Progressring?
Native C++ library that I am using in C++/CLI project raises events giving me results,
If I try to handle the event by extending the unmanaged event, it says the ref class can only extend ref class.
I then tried to create a native event but have manged object inside it to collect the results, but I get the error cannot declare managed object in unmanaged class.
Is there anyway to get it done in one of the ways I am trying, or should I declare unmanaged result objects fill them in unmanaged event and then Marshall it ?
Edit:
class MyNativeListener: public NativeEventListener
{
private:
ManagedResultsObject ^_results;
public:
void onEndProcessing(ProcessingEvent *event)
{
_results.Value = event->value;
//Many more properties to capture
}
};
This is what I am trying, I have extended the native event listener to capture the event, but not sure how to capture the results to a managed object.
Edit2
Found this while searching on the same line as suggested by #mcdave auto_gcroot
Your native class needs to store a handle to the managed object instead of a reference to it. You can do this using the gcroot template. If you dig into the gcroot template you will find it uses the GCHandle Structure, which with appropriate static casting can be stored as a void* pointer and so provides a means of storing managed references in native code.
Try expanding your code along the following lines:
#include <vcclr.h>
class MyNativeListener: public NativeEventListener
{
private:
gcroot<ManagedResultsObject^> _results;
public:
void onEndProcessing(ProcessingEvent *event)
{
_results->Value = event->value;
//Many more properties to capture
}
};