I have a main app and a plugin. The main app is exporting an IHost object and the plugin is importing an IHost object. I ran mefx and it recognizes both of those. But when I do /causes on the plugin it gives me a ImportCardinalityMismatchException. My container sees the plugin, but when I call Me.container.getExports(of IController)() it doesn't return anything.
My Controller looks like this:
Class Controller
Implements IController
' ...
<Import()>
Public Property Host As Lazy(Of IHost)
' ...
End Class
I had to <ImportMany()> in my plugin. Then for the variable I was importing to I needed to make it IEnumerable(Of Lazy(Of IHost)) Or use Lazy(of IHost) if you want to do a <Import()>
Related
I have a command class with a dependency type-hinted in the constructor:
class RunAnalyticsCommand extends Command
{
public function __construct(Analytics $analytics)
{
//
}
}
The constructor for the Analytics class looks like this:
class Analytics
{
public function __construct(Odoo $odoo, ChannelInterface $channel)
{
//
}
}
In a service provider, I've instructed the application what to instantiate for the Odoo class. If I create an instance of Analytics like this, it works fine. It gets the Odoo instance from the container and uses the channel that I pass in.
$analytics = app(Analytics::class, ['channel' => new ChannelA]);
Now, I'm trying to use contextual binding to accomplish all of this "behind the scenes". I write the following in my service provider's register method:
$this->app->when(RunAnalyticsCommand::class)
->needs(Analytics::class)
->give(function () {
return app(Analytics::class, ['channel' => new ChannelA]);
});
However, now when I run the RunAnalyticsCommand, I get an error that Maximum function nesting level of '256' reached, aborting!
I'm assuming this happens because the give callback is trying to resolve the same Analytics class, and the container treats that call as if it was also coming from the RunAnalyticsCommand class, so it just keeps trying to resolve the same thing over and over.
Is this the expected behavior or a bug with contextual binding? Shouldn't the call to resolve the class from within the give callback not behave as if it were originating from the RunAnalyticsCommand? Is there some other way to tell the container to resolve without using the contextual binding?
I usually use parameters like this:
public function test($parameter)
{
echo 'Parameter value: ' . $parameter;
}
While looking at laravel service container I see this code.
public function __construct(UserRepository $users)
{
$this->users = $users;
}
According to the documentation it uses reflection.But i dont understand.
I dont know how the parameter UserRepository $users works. Is that an alias or something?
This is called type-hinting and is used to inject dependencies in a constructor or to validate the right type of argument is passed to a function. The injection simply means that if the class is called with the make method, Laravel will automatically provide an instance of the class required by your constructor.
For example if you have a function public function something(string $something) it would throw an error if any other type than a String is passed to this function, making sure the right data is used.
From the laravel documentation:
Alternatively, and importantly, you may "type-hint" the dependency in the constructor of a class that is resolved by the container, including controllers, event listeners, queue jobs, middleware, and more. In practice, this is how most of your objects should be resolved by the container.
For example, you may type-hint a repository defined by your application in a controller's constructor. The repository will automatically be resolved and injected into the class:
Laravel has a great service container and it makes all dependency injections, so you don't need to pass a class a parameter, laravel do it for you.
without container you have to pass this parameter
class A {
public $foo;
public function __construct (Foo $foo){
$this->foo
}
$classA = new A((new Foo))
When laravel encounter with these classes, it resolves them.
Also you can define manually these classes using singleton() or bind() methods
$this->app->singleton('FooBar', function($app)
{
return new FooBar($app['SomethingElse']);
});
Or you may use interfaces. You can bind implemented class for to the interface and laravel when encounter with that interfance, it will resolve as you wish
$this->app->bind('App\ICacheManager', 'App\RedisManager');
public $redis;
public function __contruct(ICacheManager $redis){
$this->redis = $redis;
}
for more further check out laravel service container
I need a way to load objects via IoC provider depending on a request parameter. Right now I'm loading my objects directly with App::make(xy, [$urlParamter] which I want to refactor, so that I can use dependency injection the way it is supposed to. To describe my current architecture I need to show you quiet some information and in the end you find my concrete questions I have about it.
I'm building up a general CMS framework which provides an import architecture that is extendable with a custom import implementation.
Now I'm struggling with properly loading the concrete classes via IoC container, because they always depend on the selected import.
To dig into my problem, here is my entry point in routes.php
Route::get('/import', ['as' => 'overview', 'uses' => '\CMSFramework\Http\Controllers\Import\ImportController#index']);
This generates a view where the user selects a concrete import to be triggered. After selecting a concrete import, the user should get individual views to prepare the appropriate import (i.e. Upload a CSV file, select an area to import, etc.)
In my concept an import implementation consist of:
A controller class, to implement specific (peraration-) tasks like uploading a CSV file. It inherits from a base controller of the cms framework
An import "business" or "service" class, that implements how the data is getting imported (and may further delegate to queued jobs etc.)
The CMS framework part consists of:
A base controller class for all common/shared import tasks like (start the prepared import, clean all working data, etc.)
A base service class ImportBase where all implementations inherit from. It provides an interface to receive a progress for any import and implements shared operations like cleaning up working data, etc.)
An ImportStatus class which is part of the ImportBase-Class via $ImportBase->status() to handle all runtime status informations (like "is the job still running, what is the progress). This class also provides a containter for a so called "payload" that allows any conrete import implementation to push and fetch custom status informations (ie. any sub-process has been finished)
So back to my IoC architecture. After the user selected a concrete import, the following route delegates the action to the custom import implementation's controller. If it's a framework supported standard-action like via URL /import/<importkey>/clean, the inherited BaseController of the cms framework takes over and handles the request
Route::get('/import/{key}/{method}', ['uses' => function($key, $method) {
return App::make('\\MadeleinePim\\Http\\Controllers\\Import\\'.ucfirst(camel_case($key)).'Controller')->$method($key);
}]);
I know that this direct binding via a naming convention can be improved (maybe via a custom configuration file), but for now this works for me.
Now I need to show an example of how I tried to implement a concrete import target in my controller via /import/<importkey>/seedCsvDataToDatabase:
public function seedCsvDataToDatabase($key)
{
// The IoC binding is shown in next code snippet. I did not found a good way to use method injection because
// of the route-specific parameters that control the responsible import implementation
$import = \App::make(Import::class, [$key]);
// Now trigger the import service operation of that concrete import implementation (probably bad design here)
$import->seed();
// Now, that this preparation task is done, I use the ImportStatus object which is part of the Import to store
// status informations. With this I can then decided in which step the user is (Think of it like a wizard to
// prepare any import)
$import->status()
->set(ConcreteImport::STATUS_SEEDED, true)
->set(ConcreteImport::STATUS_SEEDED_DURATION_SECONDS, (microtime(true) - $time_start) / 60);
// Back to controller method that determines in which status the import is to delegate/redirect to different
// views.
return redirect('/import/<importkey>');
}
My IoC binding for the Import class:
$this->app->singleton(Import::class, function ($app, array $parameters) {
$importKey = head($parameters);
// There is a config file that provides the class names of the concrete import implementations
$importClassName = config()->get('import.' . $importKey);
if (!$importClassName) {
throw new ImportNotFoundException($importKey, "Import with key '{$importKey}' is not setup properly'");
}
$importReflectionClass = new \ReflectionClass($importClassName);
return $importReflectionClass->newInstance($importKey);
});
And finally, the lazy loading of the import status, which is encapsulated in the ImportStatus object looks like this
public function status()
{
if (!$this->status) {
$this->status = \App::make(ImportStatus::class, [$this->key()]);
}
return $this->status;
}
I hope that demonstrates the way I try to resolve my import objects from the IoC container.
My learning so far is, that this is not the right way to inject my objects.
Is the assumption right, that I should not pass the $importKey at runtime to the App::make() and rather should try to make this independ?
My failed attempt on this was to make the IoC binding smarter and let it access the Request to properly inject my concrete import object with the required $importKey, like (pseudo code!):
$this->app->bind(ImportStatus::class, function(Container $app) {
// Did not find a good way to access the {key}-part of my route /import/{key}/{method}
$key = $app->make(Request::class)->get('key'); // Does not work like this
return new \Scoop\Import\ImportStatus($key);
});
Does this approach can work like this?
Can I somehow pass through the $importKey from my route to the ServiceProvider (or better pull it from there?)
Is there a better solution to initialize my concrete import implementations?
----------
UPDATE 1
For my lattest idea to access the Route in my IoC Binding, I got this way working:
$this->app->singleton(Import::class, function (Container $app) {
$importKey = \Route::current()->getParameter('key');
$importClassName = config()->get('import.' . $importKey);
$importReflectionClass = new \ReflectionClass($importClassName);
return $importReflectionClass->newInstance($importKey);
});
Nevertheless the idea of #Sandyandi N. dela Cruz to use a router binding prevents the direct coupling between the Binding and the Request which still doesn't feel right. Using router-binding to couple a request parameter to an implementation, sounds more appropriate.
I think you've dwelt to much on the IoC container there. Why not implement the Factory pattern and do a route binding instead of creating multiple controllers to handle different Imports? Crude example as follows:
Create a route binder - edit your app/Provider/RouteServiceProvider.php's boot() method
public function boot(Router $router)
{
parent::boot($router);
// Add the statement below.
$router->bind('import', 'App\RouteBindings#import');
}
Create the App\RouteBindings class as app/RouteBindings.php
Create an import() method with the following:
public function import($importKey, $route)
{
switch ($importKey) {
case 'import_abc':
return new ImportAbc;
break; // break; for good measure. ;)
case 'import_xyz':
return new ImportXyz;
break;
// and so on... you can add a `default` handler to throw an ImportNotFoundExeption.
}
}
Create a route for resolving an Import class.
Route::get('import/{import}/{method}', 'ImportController#handleImport');
Here, {import} will return the proper Import concrete class based on your URL.
In your ImportController's handleImport() you can do the following:
public function handleImport(Import $import, $method)
{
// $import is already a concrete class resolved in the route binding.
$import->$method();
}
So when you hit: http://example.com/import/import_abc/seed, the route binding will return a concrete class of ImportAbc and store it in $import on your handleImport() method, then your handleImport() method will execute: $import->seed();. Tip: you should probably move other controller logic such as $import->status()->set() into the Import class. Keep your controllers thin.
Just make sure your Import classes have the same signature.
It's kinda like Laravel's Route Model Binding except you create the logic for the bindings.
Again, this is just a crude example but I hope it helps.
Our project allows the users to create custom theme files. Because of the way the project is structured, we have to render these files and save the output. The project uses Symfony2.
In order to render this Twig template and save the output to another file, I use a service which takes #templating as its argument.
The services.yml defines the service like this:
theme_renderer:
class: ApiBundle\Service\ThemeRenderer
arguments: [ #templating ]
This gives me a TwigEngine object that I can use like this:
public function __construct(TwigEngine $templateEngine) {
$this->templateEngine = $templateEngine;
}
public function renderTheme($filePath, $themeSettings) {
...
$renderedFileContents = $this->templateEngine->render($sourceFilePath, $themeSettings);
...
}
This works fine.
However, if the template contains an {{ asset('images', 'some_image') }} tag, the rendering fails. The exception is:
An exception has been thrown during the rendering of a template ("There is no "some_image" asset package.") in "<template_file_path_here>" at line 2
I need to be able to give a custom (CDN actually) URL for the rendering of the asset() tag. How would I go about doing this?
I think exception message There is no "some_image" asset package. is clear. Second argument of asset function is package name. Packages for templating component are defined under framework.templating key in Symfony configuration (etc. config.yml).
http://symfony.com/doc/current/reference/configuration/framework.html#packages
# app/config/config.yml
framework:
# ...
templating:
packages:
avatars:
base_urls: 'http://static_cdn.example.com/avatars'
Then you can use asset('my_image.jpg', 'avatars'). So, I suppose you have not defined package some_image or configured it improperly.
I would like to have a method available to all Views in my app.
I would like to be able to make calls like this:
<span>${ getDynamicText() }</span>
The most obvious ways (to me) to implement this are:
Call the method in the controller and and pass it to the View.
Make the method static on some Util class and call it from the code ${ UtilClass.getDynamicText() }
Using meta programming to somehow make the method available to all Views.
The benefit of #3 is that the change would only have to be made in one place. #1 would have to be made in each controller action; and #2 would need an import on every View page which wants to use the method.
So is there a way to add a method to be available to all views in my app?
I have to admit I don't know in a lot of detail how .gsp files are processed behind-the-scenes so maybe they don't have a corresponding class and therefore can't be manipulated in this way. Links to good articles/docs will get extra good karma.
GSPs are compiled into classes that extend org.codehaus.groovy.grails.web.pages.GroovyPage, so you can add methods to that metaclass and they'll be available to all GSPs. The best place to do this is in BootStrap.groovy (or in a plugin's doWithDynamicMethods closure):
import org.codehaus.groovy.grails.web.pages.GroovyPage
class BootStrap {
def init = { servletContext ->
GroovyPage.metaClass.getDynamicText = { ... }
}
}
The recommended way to reuse functionality across GSPs is to define it as a tag, e.g.
class MyTagLib {
static namespace = 'my'
def dynamicText = {attrs ->
out << 'not very dynamic'
}
}
You can then call this tag in a GSP using:
<my:dynamicText/>
4th way: make a class/service that have method '.getDynamicText' and put it's intance into request at before filter ( request.setAttribute('x', myDynamicTextGeneratorObject) )
Now you can use x.dynamicText in any GSP
This is how I would do it:
Add a new class to your controllers folder containing your method
Do a grails install-templates
Navigate to the templates: \src\templatesscaffolding
Add the extends part to the controller template: class ${className}Controller extends NewController
re-generate your controllers
You can now use the method in every class and gsp.