Magento – Magento2 Passing Arguments to class in Construct

dependency-injectionmagento-2.1object-managersolr

I am trying to instantiate the below class in my custom code

\Magento\Solr\Model\Client\Solarium

    public function __construct(
        \Magento\Solr\Model\Client\Solarium $solr
     )
{....}

However this is not working because this class requires arguments in its constructor and throws up error

We were unable to perform the search because of a search engine
misconfiguration.

But I am able to initialize using objectManager

$options = array(
            'hostname' => $this->_solrHelper->getSolrConfigData('server_hostname'),
            'login' => $this->_solrHelper->getSolrConfigData('server_username'),
            'password' => $this->_solrHelper->getSolrConfigData('server_password'),
            'port' => $this->_solrHelper->getSolrConfigData('server_port'),
            'path' => $path
        );
 $solrClient = $this->_objectManager->create('\Magento\Solr\Model\Client\Solarium', ['options' => $options]);

I am aware that using objectManager is not the right approach

So, how do I instantiate a class that requires parameters in its constructor?

Best Answer

Use a factory:

public function __construct(
    \Magento\Solr\Model\Client\SolariumFactory $solrFactory
 )

Don't worry if this class does not exist, Magento will generate it for you.

Then you can instantiate it like this:

$options = [ ... ];
$solr = $solrFactory->create(['options' => $options]);

Related Solutions

Magento 2 – Dependency Injection Constructor Arguments

I haven't actually tracked this down through code, but here's how I've come to reason about it, and the behavior described below appears to be true (even if the behind the scenes code used by the object manager is different). That said, your question leaves some important details out and is a little vague -- see comments below for some requested clarification that might clear things up.

When the object manager instantiates an object, it looks at your class's __construct method. If your class doesn't have a __construct method, then it looks at the next class's __construct method, etc. until it finds a class with a __construct. Once found, it uses those constructor parameters, and those paramaters only, to build a list of parameters to inject.

Put another way, the object manager will inject the parameters in the constructor PHP would normally call. Remember, PHP only calls one constructor. If you want a parent's constructor class to be called, you need to do parent::__construct(...). This means if the parent class needs a specific list of parameters, its your job to ensure they're also injected in your constructor (so that you can pass them on with parent::__construct).

Regarding your specific questions

Now for learning purposes i did this to see with is being injected (it doesn't take more then two arguments by default).

Your testing methodology seems like it might be a problem here. I tried creating a __construct method in a custom frontend controller that looked like this

public function __construct($a, $b)
{
    var_dump(get_class($a));
    var_dump(get_class($b));
}

And Magento/PHP yelled at me

Missing required argument $a of Pulsestorm\Commercebug\Controller\Lookup\Index

It's also unclear from your questions if these were frontend or backend controllers. If you include more specific code and expand on the steps you used to create your controller, someone may be able to help you understand why the constructor receives a Context object and a page factory object

Regarding the Magento\Sales\Controller\Adminhtml\Order\AbstractMassAction class: If your class extends this class, Magento will inject what parameters are in your __construct method. If your class doesn't have a __construct method, they you don't need to worry about what's injected. Magento will handle it for you via the parent class.

Magento 2 – Object Manager Passing Unexpected Object

TL;DR

If you see a an error with Interceptor.php be sure to empty /var/generation/ before you look further. It will save you lots of time.

Explanation

After some testing I found the underlying cause. When executing a custom controller for the first time Magento automatically generates files. So far so good. In my case just one. It's living in var\generation\ The full path in this example would be var\generation\Demo\Hello\Controller\Adminhtml\Order\MassPrint\Interceptor.php.

This class is extending your custom controller. So naturally it is calling the parent constuctor in its own constuctor. So if you make changes to your controller constructor this file must be regenerated to mach your new code. If you don't it will yield unwanted results. So be sure to at least delete the Interceptor class for that controller. Easier would be to empty the whole director so Magento will regenerate all files matching your new code.

rm -rf var/generation/*

Actually magento gives a very good clue where to look in the last part of the error message.

called in /var/generation/Demo/Hello/Controller/Adminhtml/Order/MassPrint/Interceptor.php on line 15

Best Answer

Related Solutions

Magento 2 – Dependency Injection Constructor Arguments

Magento 2 – Object Manager Passing Unexpected Object

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