I'm putting together a ZF based CMS at the moment, and am currently caching my Zend_Navigation object, as well as the html rendered by renderMenu(). So at the moment, whenever the menu changes, I have to call the following lines in the relevant action:
$cache = Zend_Registry::get("cache");
$cache->remove("menu");
$frontcache = Zend_Registry::get("frontcache");
$frontcache->remove("menuhtml");
I have a siteController to handle changes to the menu structure, and a pageController to handle add/edit/delete of individual pages, so the code is used in actions in both of these controllers.
I would obviously like to put this code in a single method I can call, but where would be the most appropriate place? An action helper? A parent class for siteController & pageController? Should I combine the controllers? Or something else?
Have you looked at using an Action Helper ( http://framework.zend.com/manual/en/zend.controller.actionhelpers.html )? This will give you a place that's independent of your controllers that each controller will still be able to call.
How about a service? Application_Service_Navigation (or whatever appnamespace you are using) stored in application/services/Navigation.php, implementing an interface representing the CRUD operations in those two CMS controllers. Then internally, these methods can use the cache as you have described. Controllers call the service methods and are unaware of the cache operations.
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I've just created my first c# / XAML application using mvvmlight and I've tried to implement the MVVM pattern as best I can (WP8 app). However, I've slowly morphed my code in to a certain style and I don't think its correctly implementing the pattern! Any advice on how things are supposed to be would help enormously.
For example, using mvvmlight I am making heavy use of the ViewModelLocator. Some of my viewmodels get created right away, like the SettingsViewModel (there is a SettingsView).
SimpleIoc.Default.Register<SettingsViewModel>(true);
And then elsewhere in my project, my other viewmodels will directly access this viewmodel for occasional information via a property or a method... like this;
mySetting = ViewModelLocator.SettingsStatic.GetSomeSetting(var);
My concern is that my viewmodels are talking to each other in this way more and more. The issue with this is that they probably can't be tested independently now because they require or assume the existence of other viewmodels.
Any pointers here would be great!
EDIT: Another example is having a PersonView, and the PersonViewModel has some helper methods for UI display. In some cases I have other views that need to display this info.... and I use the viewmodellocator to get to them, rather than writing the helper methods again in the current viewmodel.
You are right in thinking that viewmodels being dependent on viewmodels is going to cause trouble. When I need to have access to "global" settings in my app, I use an interface that can be injected in the constructor of the view model. So, You can create an ISettingsService that contains the properties and methods you need. You also create a design time setting service that mimics or fakes the data/properties of the ISettingsService Interface
then in your view model locator you use this:
if (ViewModelBase.IsInDesignModeStatic) {
SimpleIoc.Default.Register<ISettingsService, DesignSettingService>();
} else {
SimpleIoc.Default.Register<ISettingService, SettingService>();
}
Create the DesignSettingService and SettingService which both implement the ISettingsService.
As for you vewmodels, the SimpleIOC will resolve/inject the required elements passed into the constructor of the class. If you have a class/viewmodel called MyViewModel and it wanted to use the settingsservice then you would define the constructor like this:
private ISettingsService _SettingsAccess;
public New(ISettingsService SettingsService)
{
_SettingsAccess = SettingsService;
SettingProperty= _SettingsAccess.GetProperty;
}
This keeps the viewmodels decoupled as this service is resolved in the constructor, that way you can change the implementation of your ISettingsService without breaking every viewmodel that uses it.
I use a INavigationService to handle all the navigation events in my app, this allows me to cancel navigation based on another viewmodels properties without needing the other viewmodel to be directly called/referenced by the current one.
One view model should never directly call another view model. Using this method you can pass as many "services" as are needed to the viewmodel. Every viewmodel I use gets a dataservice that connects to my model in addition to the navigationservice. Ie. A viewmodel that deals with people gets an IPeopleDataService where this service contains all the CRUD operations that affect the database. That way I can change the people objects in the database and service functions without having to change the people viewmodel as well.
I hope this helps.
We've been using the recommended GWT approach of building parts of our application in an MVP manner. The logic we use is based on Google's examples - the Presenter fetches/prepares data and sets it on the View, and the View contains a reference to the Presenter which it calls (e.g. in UiHandlers).
Some parts of the application which we built should be reused in other views. For example - a view which is sometimes the "main view" of a part of the application - can be used inside a pop-up in another part of the application (of course, the views/presenters are initialized differently in this other case, but basically it is the same thing).
What would be the correct approach to do stuff like this? I cannot seem to find a suitable one without resorting to ugly hacky stuff.
For example - if I put the presenter of the reused component inside the main view - it is easy to initialize the reused component, but it is ugly to receive a result back in the main presenter. This can be solved by passing a runnable or creating a custom handler or passing the parent presenter itself to the reused presenter.
All of these approaches don't seem right to me though and seem ugly.
Any ideas/experiences?
What you're describing is a view being able to be controlled by 2 distinct presenters. Abstracting those presenters behind a common API, in the form of an interface, should be enough.
You can also see it as a composite widget being used within two distinct views. The composite widget would then expose events and a public API that both views could wire to their specific presenters.
See Activites and Places,It can help you to desing and structure you app.
https://developers.google.com/web-toolkit/doc/latest/DevGuideMvpActivitiesAndPlaces
.
Having worked with .net in both winforms and ASP.net for a few years I am now starting to get into MVC (a little late I know). One major confusion for me is the concept of reusable 'components', similar to the concept of a usercontrol in webforms.
For example, I would like to have a number of 'widgets' within the members area of my site, one of which is the details of the logged in users account manager. I can create this as a partial however when the page loads the data needs to be passed in as part of the ViewModel / View Data. I would like to use this widget in a number of different sections which would then mean that I need to put the code to pass the data in into a number of different controllers. This seems to violate the DRY principle, or am I missing something here? I would ideally like everything to be encapsulated within the 1 partial which can then be used in any page.
You can go three ways:
1) For simple controls without much logic, you can create new instance of the custom view model for the control:
Html.RenderPartial("YourControl", new YourControlViewModel () { Param1="value1", Param2 = Model.AnotherValue });
2) If you need some back end logic for the control, you can use
Html.RenderAction("ActionName", "SomeControllerName", RouteValuesDictionary);
It will call standard controller action, use the view, and insert the resulting output back to the page. You can add [ChildActionOnly] atribute to the controller method to ensure that the method will be available only from the Html.RenderPartial. It is slightly violating the MVC principle (view shouldn't call controller), but its great for widgets, and it is used in the Ruby on Rails world without much issues. You can check great article from Haacked
3) Create custom html helper for tasks like custom date formatting, calculating etc..
In your case, I would choose the number two.
I have a layout which works fine. This layout contains several partials, which display adverts, a side column a slideshow, etc. All of these are likely to change depending on which page (module/controller/action) of the site you are on.
What is the best way of doing this correctly? In the past I have assigned variables to my view inside my controllers, these are then passed to the partial which then displays the correct slideshow or advert. This seems ugly and not entirely correct for an MVC application.
Does anyone have any other methods of doing this?
Partials are just another view scripts.
My advice is: newer put your logic into the view scripts. Your may store the logic in:
models (remember, that you can create your own models, extending, or not extending the basic database models, eg. data hydrators)
view helpers (with parameters)
services (dependent on models, returning models)
combination of the above
Then use view helper or pass the ready data (model) to different partials.
Tip: Dependency injection is a good thing.
Could someone give few tips and/or examples how Controller Plugins and Action Helpers are different? Are there situations where particular task could be accomplished with one but not another? For me they both look more or less the same and I'm often having trouble having to decide when to use what... Are there any big differences?
Controller plugins can hook into any controller at any point in the routing process (preDispatch postDispatch, routeStartup, routeShutdown) which makes them apt at providing behind the scenes functionality like ACL enforcement.
Action Helpers are for for reusable but optional segments that your controller might need to access (redirector, flashMessenger).
So if you are creating a reusable snippet of code that always needs to execute itself then use a controller plugin, otherwise you probably want an action helper.
You can think of it this way:
Action helpers are used to add methods to controllers.
Controller plugins are used to add routing / dispatch logic to controllers.
So ask yourself, do I have a method that I would like to be able to call from all actions in my controller? Or do I need to add logic to the routing / dispatch process.
You might also have a look at the the Built in Action Helpers.
A picture to illustrate the difference between plugins and action helpers:
ZF Sequence Flow
Action helpers also have access to the actual controlller object that's being executed. Controller Plugins only have access to the FrontController, and therefore only the controller and action name.
Which you use depends on what context you need. If you need to access a view object attached to a controller, for example, you will want an Action Helper.
Also notice that, in the front controller life-cycle process, the plugins get the control(or invoked) first than the action helpers.