GWT Editor framework - gwt

Is there a way to get the proxy that editor is editing?
The normal workflow would be:
public class Class implments Editor<Proxy>{
#Path("")
#UiField AntoherClass subeditor;
void someMethod(){
Proxy proxy = request.create(Proxy.class);
driver.save(proxy);
driver.edit(proxy,request);
}
}
Now if i got a subeditor of the same proxy
public class AntoherClass implements Editor<Proxy>{
someMethod(){
// method to get the editing proxy ?
}
}
Yes i know i can just set the proxy to the Child editor with setProxy() after its creation, but i want to know if there is something like HasRequestContext but for the edited proxy.
This usefull when you use for example ListEditor in non UI objects.
Thank you.

Two ways you can get a reference to the object that a given editor is working on. First, some simple data and a simple editor:
public class MyModel {
//sub properties...
}
public class MyModelEditor implements Editor<MyModel> {
// subproperty editors...
}
First: Instead of implementing Editor, we can pick another interface that also extends Editor, but allows sub-editors (LeafValueEditor does not allow sub-editors). Lets try ValueAwareEditor:
public class MyModelEditor2 implements ValueAwareEditor<MyModel> {
// subproperty editors...
// ValueAwareEditor methods:
public void setValue(MyModel value) {
// This will be called automatically with the current value when
// driver.edit is called.
}
public void flush() {
// If you were going to make any changes, do them here, this is called
// when the driver flushes.
}
public void onPropertyChange(String... paths) {
// Probably not needed in your case, but allows for some notification
// when subproperties are changed - mostly used by RequestFactory so far.
}
public void setDelegate(EditorDelegate<MyModel> delegate) {
// grants access to the delegate, so the property change events can
// be requested, among other things. Probably not needed either.
}
}
This requires that you implement the various methods as in the example above, but the main one you are interested in will be setValue. You do not need to invoke these yourself, they will be called by the driver and its delegates. The flush method is also good to use if you plan to make changes to the object - making those changes before flush will mean that you are modifying the object outside of the expected driver lifecycle - not the end of the world, but might surprise you later.
Second: Use a SimpleEditor sub-editor:
public class MyModelEditor2 implements ValueAwareEditor<MyModel> {
// subproperty editors...
// one extra sub-property:
#Path("")//bound to the MyModel itself
SimpleEditor self = SimpleEditor.of();
//...
}
Using this, you can call self.getValue() to read out what the current value is.
Edit: Looking at the AnotherEditor you've implemented, it looks like you are starting to make something like the GWT class SimpleEditor, though you might want other sub-editors as well:
Now if i got a subeditor of the same proxy
public class AntoherClass implements Editor<Proxy>{
someMethod(){
// method to get the editing proxy ?
}
}
This sub-editor could implement ValueAwareEditor<Proxy> instead of Editor<Proxy>, and be guaranteed that its setValue method would be called with the Proxy instance when editing starts.

In your child editor class, you can just implement another interface TakesValue, you can get the editing proxy in the setValue method.
ValueAwareEditor works too, but has all those extra method you don't really need.

This is the only solution I found. It involves calling the context edit before you call the driver edit. Then you have the proxy to manipulate later.

Related

Wicket: AjaxRequestTarget vs onModelChanged

I'm working on a code in a wicket project, where the original devs used the onModelChanged() method quite a lot in Ajax request handling methods. I, for one, however am not a strong believer of this implementation.
In fact, I can't think of any examples, where calling the target.add(...) is inferior to calling the onModelChanged method.
Am I missing some key concepts here?
Example:
public MyComponent extends Panel {
public MyComponent(String id, Component... componentsToRefresh) {
add(new AjaxLink<Void>("someId") {
#Override
public void onClick(AjaxRequestTarget target) {
// some logic with model change
for(Component c: componentsToRefresh) {
c.modelChanged();
}
target.add(componentsToRefresh);
}
};
}
}
Now, there are a couple of things I don't agree with, the very first is the componentsToRefresh parameter, the second is (as the question suggests), the fact that we called c.modelChanged() on all components in that array. My guess would be that it is completely un necessary and instead of a parameter in the constructor, one should just write an empty function in MyComponent and override it, and put the necessary components in there when needed.
I would suggest to use Wicket Event system instead. That is, whenever the AjaxLink is clicked you will broadcast an event:
send(getPage(), Broadcast.BREATH, new MyEventPayload(target));
This will broadcast the event to the current Page and all its components.
Then in any of your components you can listen for events:
#Override
public void onEvent(IEvent event) {
Object payload = event.getPayload();
if (payload instanceof MyEventPayload) {
((MyEventPayload) payload).getTarget().add(this); // or any of my sub-components
event.stop(); // optionally you can stop the broadcasting
}
}
This way you do not couple unrelated components in your application.
See Wicket Guide for more information.

TypeScript: Access global type hidden by local class definition?

Lets assume i have a class which has the same name as an previously defined type which is defined inside lib.d.ts. How would i make use of that type within this class.
For example, i have the class Event, which has to deal with the browsers Event object, which is defined as an interface in lib.d.ts.
export class Event { // own definition of Event which hides original Event
public dealWithBrowserEvent(event: Event): void { // Event object defined by lib.d.ts
// deal with it
}
}
How would i tell Typescript that this are two different types. Of course i could simply rename my class, but i don't want to do that, because the name is perfect for my use case.
You can archive this by doing so:
E.ts:
class CustomEvent
{
public dealWithBrowserEvent(event: Event): void
{
}
}
export default CustomEvent;
A.ts:
import Event from './E'
export class SomeClass
{
//Parameter e here is instance of your CustomEvent class
public someMethod(e: Event): void
{
let be: any;
//get browser event here
e.dealWithBrowserEvent(be)
}
}
More on declaration merging, and what can be merged and what not: link
I strongly recommend you not doing so. This code will lead to a lot of confusion for your colleagues reading/modifying it later, let alone headache of not being able to use in the same file standard class for Event.
In the meantime i found a quite doable solution. I defined an additional module which exports renamed interfaces. If i import this module, i can use the renamed types as if they would be original types.
browser.ts
// Event will be the one from lib.d.ts, because the compiler does not know anything about
// the class Event inside this module/file.
// All defined properties will be inherited for code completion.
export interface BrowserEvent extends Event {
additionalProperty1: SomeType;
additionalProperty2: SomeType;
}
If you don't need additional properties you can just do type aliasing:
browser.ts
// Alias for Event
export type BrowserEvent = Event;
event.ts
import {BrowserEvent} from './browser.ts';
export class Event { // Definition of Event hides original Event, but not BrowserEvent
public dealWithBrowserEvent(event: BrowserEvent): void {
// deal with it
}
}
I'm quite happy with this solution, but maybe there is a even better solution.

wicket :how to combine CompoundPropertyModel and LoadableDetachableModel

I want to achieve two goals:
I want my model to be loaded every time from the DB when it's in a life-cycle (for every request there will be just one request to the DB)
I want my model to be attached dynamically to the page and that wicket will do all this oreable binding for me
In order to achieve these two goals I came to a conclusion that I need to use both CompoundPropertyModel and LoadableDetachableModel.
Does anyone know if this is a good approach?
Should I do new CompoundPropertyModel(myLoadableDetachableModel)?
Yes, you are right, it is possible to use
new CompoundPropertyModel<T>(new LoadableDetachableModel<T> { ... })
or use static creation (it does the same):
CompoundPropertyModel.of(new LoadableDetachableModel<T> { ... })
that has both features of compound model and lazy detachable model. Also detaching works correctly, when it CompoudPropertyModel is detached it also proxies detaching to inner model that is used as the model object in this case.
I use it in many cases and it works fine.
EXPLANATION:
See how looks CompoundPropertyModel class (I'm speaking about Wicket 1.6 right now):
public class CompoundPropertyModel<T> extends ChainingModel<T>
This mean, CompoundPropertyModel adds the property expression behavior to the ChainingModel.
ChainingModel has the following field 'target' and the constructor to set it.
private Object target;
public ChainingModel(final Object modelObject)
{
...
target = modelObject;
}
This take the 'target' reference to tho object or model.
When you call getObject() it checks the target and proxies the functionality if the target is a subclass of IModel:
public T getObject()
{
if (target instanceof IModel)
{
return ((IModel<T>)target).getObject();
}
return (T)target;
}
The similar functionality is implemented for setObject(T), that also sets the target or proxies it if the target is a subclass of IModel
public void setObject(T object)
{
if (target instanceof IModel)
{
((IModel<T>)target).setObject(object);
}
else
{
target = object;
}
}
The same way is used to detach object, however it check if the target (model object) is detachable, in other words if the target is a subclass if IDetachable, that any of IModel really is.
public void detach()
{
// Detach nested object if it's a detachable
if (target instanceof IDetachable)
{
((IDetachable)target).detach();
}
}

GWT Request Factory and Editor Framework Exception

When attempting to edit a new (proxy) entity using RequestFactoryEditorDriver.edit() I am getting the following error: "Exception caught: Attempting to edit an EntityProxy previously edited by another RequestContext". I am fairly sure that this is a result of my misunderstanding of the request factory/editor framework architecture. Here is the editor code that I think pertains to this problem:
public class OrgMaintenanceWidget extends Composite implements Editor<IOrgProxy> {
... other fields ...
private IOrgEditorDriver _orgEditorDriver;
interface IOrgEditorDriver extends RequestFactoryEditorDriver<IOrgProxy, OrgMaintenanceWidget> {}
public OrgMaintenanceWidget(final IClientFactory clientFactory) {
... widget initialization ...
_orgEditorDriver = GWT.create(IOrgEditorDriver.class);
_orgEditorDriver.initialize(_clientFactory.getRequestFactory().getEventBus(),
_clientFactory.getRequestFactory(), this);
}
#UiHandler("newButton")
public void onNewButtonClick(final ClickEvent clickEvent) {
_org = _clientFactory.getCache().getOrgCache().newOrg();
_orgEditorDriver.edit(_org, _clientFactory.getRequestFactory().orgRequestContext());
}
...
}
It's the "_orgEditorDriver.edit()" line that causes the exception. The "newOrg()" method is:
public IOrgProxy newOrg() {
return _clientFactory.getRequestFactory().orgRequestContext().create(IOrgProxy.class);
}
The RequestFactory is simply:
public interface IRequestFactory extends RequestFactory {
IOrgRequestContext orgRequestContext();
}
I am sure that I'm missing something fundamental about editing a new entity. When I edit an existing entity everything is fine ... the UI components are populated automatically, and flushing the editor back to the entity works very nicely. Here's the code that initiates editing for an existing entity:
#UiHandler("newButton")
public void onNewButtonClick(final ClickEvent clickEvent) {
_org = _clientFactory.getCache().getOrgCache().newOrg();
_orgEditorDriver.edit(_org, _clientFactory.getRequestFactory().orgRequestContext());
}
Any help would be greatly appreciated, and I'll try to publish any lessons learned.
This code:
_clientFactory.getRequestFactory().orgRequestContext().create(IOrgProxy.class);
Means:
Create new orgRequestContext()
Create new IOrgProxy using this context
Edit new IOrgProxy using this context, because as docs say: "Returns a new mutable proxy that this request can carry to the server, perhaps to be persisted.", it means that the proxy is edited by this request.
This code:
_orgEditorDriver.edit(_org, _clientFactory.getRequestFactory().orgRequestContext());
Means:
Again, create new orgRequestContext() (because each invocation of getRequestFactory().orgRequestContext() provides new instance of orgRequestContext()
"Start driving the Editor and its sub-editors with data." as docs say. But as a part of it, use passed orgRequestContext() to edit passed IOrgProxy instance, so that the proxy is editable.
Because the proxy was already edited while created by other RequestContext, you get the exception, because there is fundamental rule in RequestFactory, that proxy can be edited only by one RequestContext.
See also this thread.
I think you can't create an object with one RequestContext and then edit it with another one.
So you can solve this in two ways:
Persist the created object with the RequestContext you used when you created the object. The save method should return the persisted object and this persisted object can be passed to the editor with a fresh new RequestContext
Somewhere save the RequestContext you used for creating the object and pass it to the edit function of your Driver
Solution two could look something like this:
#UiHandler("newButton")
public void onNewButtonClick(final ClickEvent clickEvent) {
IOrgRequestContext ctx = _clientFactory.getRequestFactory().orgRequestContext();
_org = ctx.create(IOrgProxy.class);
_orgEditorDriver.edit(_org,ctx );
}

MEF and IObservables

I have a singleton IObservable that returns the results of a Linq query. I have another class that listens to the IObservable to structure a message. That class is Exported through MEF, and I can import it and get asynchronous results from the Linq query.
My problem is that after initial composition takes place, I don't get any renotification on changes when the data supplied to the Linq query changes. I implemented INotifyPropertyChanged on the singleton, thinking it word make the exported class requery for a new IObservable, but this doesn't happen.
Maybe I'm not understanding something about the lifetime of MEF containers, or about property notification. I'd appreciate any help.
Below are the singleton and the exported class. I've left out some pieces of code that can be inferred, like the PropertyChanged event handlers and such. Suffice to say, that does work when the underlying Session data changes. The singleton raises a change event for UsersInCurrentSystem, but there is never any request for a new IObservable from the UsersInCurrentSystem property.
public class SingletonObserver: INotifyPropertyChanged
{
private static readonly SingletonObserver _instance = new SingletonObserver();
static SingletonObserver() { }
private SingletonObserver()
{
Session.ObserveProperty(xx => xx.CurrentSystem, true)
.Subscribe(x =>
{
this.RaisePropertyChanged(() => this.UsersInCurrentSystem);
});
}
public static SingletonObserverInstance { get { return _instance; } }
public IObservable<User> UsersInCurrentSystem
{
get
{
var x = from user in Session.CurrentSystem.Users
select user;
return x.ToObservable();
}
}
}
[Export]
public class UserStatus : INotifyPropertyChanged
{
private string _data = string.Empty;
public UserStatus
{
SingletonObserver.Instance.UsersInCurrentSystem.Subscribe(sender =>
{
//set _data according to information in sender
//raise PropertyChanged for Data
}
}
public string Data
{
get { return _data; } }
}
}
My problem is that after initial composition takes place, I don't get any renotification on changes when the data supplied to the Linq query changes.
By default MEF will only compose parts once. When a part has been composed, the same instance will be supplied to all imports. The part will not be recreated unless you explicitly do so.
In your case, if the data of a part change, even if it implements INotifyPropertyChanged, MEF will not create a new one, and you don't need to anyway.
I implemented INotifyPropertyChanged on the singleton, thinking it word make the exported class requery for a new IObservable
No.
Maybe I'm not understanding something about the lifetime of MEF containers, or about property notification.
Property notification allows you to react to a change in the property and has no direct effect on MEF. As for the container's lifetime, it will remain active until it is disposed. While it is still active, the container will keep references to it's compose parts. It's actually a little more complex than that, as parts can have different CreationPolicy that affects how MEF holds the part, I refer you to the following page: Parts Lifetime for more information.
MEF does allow for something called Recomposition. You can set it likewise:
[Import(AllowRecomposition=true)]
What this does tough is allow MEF to recompose parts when new parts are available or existing parts aren't available anymore. From what I understand it isn't what you are referring to in your question.