How do I solve "Target [Interface] is not instantiable" in Laravel 4? - php

Question

My error message:
Illuminate \ Container \ BindingResolutionException
Target [Project\Backend\Service\Validation\ValidableInterface] is not instantiable.
I understand that interfaces and abstract classes are not instantiable so I know that Laravel should not be trying to instantiate my interface. Yet somehow it's trying to and I suspect this may be a binding issue...even though I believe I have bound it correctly and have registered it as a service provider.
I should mention that I have taken this example out of Chris Fidao's "Implementing Laravel" and it's almost identical!
This is the first couple of lines of my form class:
namespace Project\Backend\Service\Form\Job;
use Project\Backend\Service\Validation\ValidableInterface;
use Project\Backend\Repo\Job\JobInterface;
class JobForm {
/**
* Form Data
*
* #var array
*/
protected $data;
/**
* Validator
*
* #var \Project\Backend\Form\Service\ValidableInterface
*/
protected $validator;
/**
* Job repository
*
* #var \Project\Backend\Repo\Job\JobInterface
*/
protected $job;
public function __construct(ValidableInterface $validator, JobInterface $job)
{
$this->validator = $validator;
$this->job = $job;
}
This is the first few lines of my validator class:
namespace Project\Backend\Service\Form\Job;
use Project\Backend\Service\Validation\AbstractLaravelValidator;
class JobFormValidator extends AbstractLaravelValidator {
// Includes some validation rules
This is the abstract validator:
namespace Project\Backend\Service\Validation;
use Illuminate\Validation\Factory;
abstract class AbstractLaravelValidator implements ValidableInterface {
/**
* Validator
*
* #var \Illuminate\Validation\Factory
*/
protected $validator;
/**
* Validation data key => value array
*
* #var Array
*/
protected $data = array();
/**
* Validation errors
*
* #var Array
*/
protected $errors = array();
/**
* Validation rules
*
* #var Array
*/
protected $rules = array();
/**
* Custom validation messages
*
* #var Array
*/
protected $messages = array();
public function __construct(Factory $validator)
{
$this->validator = $validator;
}
This is the code where I bind it all to the app:
namespace Project\Backend\Service\Validation;
use Illuminate\Support\ServiceProvider;
use Project\Backend\Service\Form\Job\JobFormValidator;
class ValidationServiceProvider extends ServiceProvider {
public function register()
{
$app = $this->app;
$app->bind('Project\Backend\Service\Form\Job\JobFormValidator', function($app)
{
return new JobFormValidator($app['validator']);
});
}
}
This is then registered in app/config/app.php:
.....
'Project\Backend\Service\Validation\ValidationServiceProvider',
....
Finally these are the first few lines of my controller:
use Project\Backend\Repo\Job\JobInterface;
use Project\Backend\Service\Form\Job\JobForm;
class JobController extends \BaseController {
protected $jobform;
function __construct(JobInterface $job, JobForm $jobform)
{
$this->job = $job;
$this->jobform = $jobform;
}

Answer 1

You need to tell Laravel which instance it should use for a certain interface when injecting it into the constructor via type hinting.
You do this using the bind() method (in your service provider for example)
$app->bind('JobInterface', 'Job'); // Job being the class you want to be used
I highly recommend you watch the video here where Taylor Otwell, the creator of Laravel, explains this and some other things.

Answer 2

First you need to bind using
/app/Providers/AppServiceProvider.php
<?php namespace App\Providers;
use Illuminate\Support\ServiceProvider;
class AppServiceProvider extends ServiceProvider {
/**
* Bootstrap any application services.
*
* #return void
*/
public function boot()
{
//
}
/**
* Register any application services.
*
* #return void
*/
public function register()
{
//
$this->app->bind('JobInterface', 'Job');
}
}
Once you complete this change
Run composer update