1 - Infos About Store

Get Current store Id :
inject \Magento\Store\Model\StoreManagerInterface $storeManage

 
$this->storeManager = $storeManager;
 

and get the id with :

 
$id = $this->storeManager->getStore()->getId();
 

get base Url :

 
$baseUrl = $this->storeManager->getStore()->getBaseUrl();
 

you can inject \Magento\Framework\UrlInterface and use use constants of class as parameters (UrlInterface::URL_TYPE_LINK) :

 
    const URL_TYPE_LINK = 'link';
    const URL_TYPE_DIRECT_LINK = 'direct_link';
    const URL_TYPE_WEB = 'web';
    const URL_TYPE_MEDIA = 'media';
    const URL_TYPE_STATIC = 'static';
    const URL_TYPE_JS = 'js';
 

get base currency code  or (getBaseCurrency() , getDefaultCurrencyCode(), getDefaultCurrency()):

 
$baseCurrency = $this->storeManager->getStore()->getBaseCurrencyCode();
 

get current currency code or (getCurrentCurrency(), getAvailableCurrencyCodes(),getAllowedCurrencies()) :

 
$currentCurrency = $this->storeManager->getStore()->getCurrentCurrencyCode();
 

Retrieve base media directory path :

 
$baseMediaDir  = $this->storeManager->getStore()->getBaseMediaDir();
 

Retrieve base static directory path :

 
$baseStaticDir  = $this->storeManager->getStore()->getBaseStaticDir();
 

For other function like website_id , group_id, code name or secure test got to class Magento\Store\Model\Store and explore …

2 – Cart Data

inject Magento\Checkout\Model\Cart $cart

 
$this->cart = $cart;
 

 

get total number items:

 
$cartCount = $this->cart->getItemsCount();
 

- get quote data :

 
$cartQuote= $this->cart->getQuote()->getData();
print_r($cartQuote);
 

you cant get  [base_currency_code]  [store_currency_code]  [quote_currency_code]  [grand_total] or [base_grand_total] and many others see all details inside print_r

 
echo $cartQuote['base_grand_total'];
 

- iterate items of cart from session :
inject Magento\Checkout\Model\Session $session
$this->session  =  $session;

 
foreach ($this->session->getQuote()->getAllItems() as $item) {
    echo $item->getName();
}
 

-clear quote

 
$this->session ->clearQuote();
 

 

3 - Catalog:

inject \Magento\Framework\Registry $registry
$this->registry = $registry;
-get current category :

 
$category = $this->registry->registry('current_category');
 

get cuurent category id:

 
$cid = $this->registry->registry('current_category')->getId();
 

get current category level:

 
$level = $this->registry->registry('current_category')->getLevel();
 

 

-get current product :

 
$pid  =$this->registry->registry('current_product');
 

retrieve crosssell products from current product:

 
        $products = [];
        foreach ($this->registry->registry('current_product')->getCrossSellProducts() as $product) {
            $products[$product->getId()] = ['position' => $product->getPosition()];
        }
        print_r($products);
 

retrieve related products from current product:

 
        $products = [];
        foreach ($this->registry->registry('current_product')->getRelatedProducts() as $product) {
            $products[$product->getId()] = ['position' => $product->getPosition()];
        }
        print_r($products);
 

retrieve upsell products from current product:

 
        $products = [];
        foreach ($this->registry->registry('current_product')->getUpSellProducts() as $product) {
            $products[$product->getId()] = ['position' => $product->getPosition()];
        }
        print_r($products);
 

test if current product is registered:

 
            if ($this->registry->registry('current_product')) {
                $product = $this->registry->registry('current_product');
            } else {
                throw new \LogicException('Product is not defined');
            }
 

4 - CMS

inject \Magento\Framework\Registry $registry
$this->registry = $registry;
-get current cms page :

 
$page = $this->registry->registry('cms_page');
 

get id of current cms page:

 
$cmsId = $this->registry->registry('cms_page')->getId();
 

test if cms page exist in table :

 
        if ($this->registry->registry('cms_page')->getId()) {
            return $this->registry>registry('cms_page')->getTitle();
        } else {
            return __('New Page');
        }
 

 

5 - View

inside any block that extend \Magento\Framework\View\Element\Template you can use :

 
//getting assets elements url from your extension in current theme
$loader = $this->getViewFileUrl("ibnab_lazy::images/loader.svg");
//or getting from assets of current theme :
$js = $this->getViewFileUrl("js/my.js");