Load objects with parameters from Laravel IoC container

Question

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.

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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)

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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?

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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.

Answer 1

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:

1. 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');
}

2. Create the App\RouteBindings class as app/RouteBindings.php
3. 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.
    }
}

4. 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.

5. 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.