Call helper functions in override block Magento 2

Question

I am trying to call helper function in override block

Whenever i am trying to add __construct in block is not loading.

Here is my code code of block

<?php
namespace Company\Module\Block\Adminhtml\Order\View;
class Items extends \Magento\Sales\Block\Adminhtml\Order\View\Items
{
    protected $_helper;
    public function __construct(
        \Company\Module\Helper\Data $helper
    ) {
        $this->_helper = $helper;
    }
    public function callhelper(){
        $this->_helper->somefuntion();
    }
}

Here is my code code of helper

<?php
namespace Company\Module\Helper;
class Data extends \Magento\Framework\App\Helper\AbstractHelper
{
    public function somefuntion()
    {
        echo 'Hello';
    }
}

Answer 1

At first thank you for your helps. I have found way how can i call helper in override block in magento 2

In my case i have override block \Magento\Sales\Block\Adminhtml\Order\View\Items in my module and want to access helper function of my module.

First we need to check if their is constructor in main class i.e. \Magento\Sales\Block\Adminhtml\Order\View\Items.php in my case their is no constructor defined in Items.php so i have checked class Items from which it is extending and found that its extending from \Magento\Sales\Block\Adminhtml\Items\AbstractItems.php their is constructor defined i have copied that constructor in my override class i.e. Company\Module\Block\Adminhtml\Order\View\Items.php and set all original constructor arguments to parent constructor here is code

constructor code of \Magento\Sales\Block\Adminhtml\Items\AbstractItems class which is extended by \Magento\Sales\Block\Adminhtml\Order\View\Items.php

public function __construct(
    \Magento\Backend\Block\Template\Context $context,
    \Magento\CatalogInventory\Api\StockRegistryInterface $stockRegistry,
    \Magento\CatalogInventory\Api\StockConfigurationInterface $stockConfiguration,
    \Magento\Framework\Registry $registry,
    array $data = []
) {
    $this->stockRegistry = $stockRegistry;
    $this->stockConfiguration = $stockConfiguration;
    $this->_coreRegistry = $registry;
    parent::__construct($context, $data);
}

constructor code of override block i.e. Company\Module\Block\Adminhtml\Order\View\Items.php

public function __construct(
    \Magento\Backend\Block\Template\Context $context,
    \Magento\CatalogInventory\Api\StockRegistryInterface $stockRegistry,
    \Magento\CatalogInventory\Api\StockConfigurationInterface $stockConfiguration,
    \Magento\Framework\Registry $registry,
    \Company\Module\Helper\Data $helper,
    array $data = []
) {
    $this->_helper = $helper;
    parent::__construct($context, $stockRegistry, $stockConfiguration, $registry, $data);
}

Cleared cache and generations from var folder and its working fine.

Answer 2

Try replacing your block constructor with

public function __construct(
    \Magento\Backend\Block\Template\Context $context,
    \Company\Module\Helper\Data $helper,
    array data = []
) {
    $this->_helper = $helper;
    parent::__construct($context, $data);
}

Since you're ultimately extending \Magento\Sales\Block\Adminhtml\Items\AbstractItems you'll need to initiate that block for everything to load properly.