Using construct instead of object manager

Question

I'm running into an error while converting below code that uses object manager to injecting within construct instead.

In this example i have this code:

$objectManager->create('Magento\ConfigurableProduct\Model\ResourceModel\Product\Type\Configurable')->getParentIdsByChild($product->getId());

So I want to use the Magento\ConfigurableProduct\Model\ResourceModel\Product\Type\Configurable within the construct so assumed i would add to my current construct like below:

//1. Add variable
protected $catalogProductTypeConfigurable;
public function __construct(
 \Magento\Catalog\Block\Product\Context $context,
 \Magento\Catalog\Model\ResourceModel\Product\CollectionFactory $productCollectionFactory,
 \Magento\Catalog\Model\Product\Visibility $catalogProductVisibility,
 \Magento\Framework\App\Http\Context $httpContext,
//2. Add Class here next to variable defined before construct 
 \Magento\ConfigurableProduct\Model\ResourceModel\Product\Type\Configurable $catalogProductTypeConfigurable,
 array $data = []
) {
 $this->_productCollectionFactory = $productCollectionFactory;
 $this->_catalogProductVisibility = $catalogProductVisibility;
 $this->httpContext = $httpContext;
 //3. Also add here so this class is passed to our variable
 $this->catalogProductTypeConfigurable = $catalogProductTypeConfigurable;
 parent::__construct(
 $context,
 $data
 );
}

So steps 1 sets variable, 2 takes class and passes to construct, and 3 sets this to a local variable. This then allow me to use getParentsIdsByChild function from $this->catalogProductTypeConfigurable.

e.g.

$this->catalogProductTypeConfigurable->getParentIdsByChild($product->getId());

This however throws following error:

 PHP Fatal error: Uncaught TypeError: Argument 5 passed to Vendor\\Module\\Block\\CustomBlock::__construct() must be an instance of Magento\\ConfigurableProduct\\Model\\ResourceModel\\Product\\Type\\Configurable, array given

I would like any advice on how to do this correctly.

• Pmclain: Have you cleared 'var/generation'? The error looks like your new constructor argument isn't being passed, which is often caused by the generated code not yet being updated.
• harri: I am using developer mode is this still necessary? Ok yeah that seems to have fixed it however
• Pmclain: Yes. The dev docs contain more detail about which caches should be cleared and when during development devdocs.magento.com/guides/v2.1/howdoi/php/php_clear-dirs.html

Answer 1

So just to tie this question up the main issue i was facing was clearing var/generation as suggested in comment my Pmclain.

Example use of object manager

$objectManager->create('Magento\ConfigurableProduct\Model\ResourceModel\Product\Type\Configurable')->getParentIdsByChild($product->getId());

This states that we require the use of Magento\ConfigurableProduct\Model\ResourceModel\Product\Type\Configurable class to use the getParentIdsByChild method

Construct should be used instead of object manager directly however so follow below steps:

1. Define Variable before construct:

protected $catalogProductTypeConfigurable;

2. Pass class to construct and set to our variable defined in step 1:

public function __construct(
 \Magento\Catalog\Block\Product\Context $context,
 \Magento\Catalog\Model\ResourceModel\Product\CollectionFactory $productCollectionFactory,
 \Magento\Catalog\Model\Product\Visibility $catalogProductVisibility,
 \Magento\Framework\App\Http\Context $httpContext,
 //a. Add Class here followed by variable defined in step 1 
 \Magento\ConfigurableProduct\Model\ResourceModel\Product\Type\Configurable $catalogProductTypeConfigurable,
 array $data = []
) {
 $this->_productCollectionFactory = $productCollectionFactory;
 $this->_catalogProductVisibility = $catalogProductVisibility;
 $this->httpContext = $httpContext;
 //b. Also add here so this class is passed to our variable
 $this->catalogProductTypeConfigurable = $catalogProductTypeConfigurable;
 parent::__construct(
 $context,
 $data
 );
}

So the class is passed through construct method and set to $this->catalogProductTypeConfigurable

3. Using the method

This then allows the use of getParentIdsByChild method by using $this->catalogProductTypeConfigurable

e.g.

$this->catalogProductTypeConfigurable->getParentIdsByChild('1');

4. Clear Generation folder

Changing of classes requires var/generation to be cleared otherwise you may run into issue stated in my question. Delete this by running below from your Magento root directory.

rm -rf var/generation/*

Credit to step 4 goes to Pmclain for helping me in comments.