Magento 2: Check condition on Click of "Proceed to Checkout"

Question

May be I need to create Event Observer. I would like to check Product's Type Condition & Display Message Accordingly on Shopping Cart Page.

  <event name="controller_action_predispatch_XXX_XX_XX">
  <observer name="checkcout_page" instance="Custom\Module\Observer\CheckShoppingCartObserver" />
  </event>

http://www.advancedcheckout.com/blog/list-event-magento2.html/

https://cyrillschumacher.com/magento2-list-of-all-dispatched-events/

It's not giving event information when it's gonna execute on, on which place/page?

What will be method i need use instead of XXX.

Answer 1

You have to just use controller_action_predispatch_checkout_index_index action to check before checkout index page is load.

 <event name="controller_action_predispatch_checkout_index_index">
    <observer name="checkcout_page" instance="Custom\Module\Observer\CheckShoppingCartObserver" />
 </event>

If you want to fire event before any action is called you have to use controller_action_predispatch_XX_XX_XX

If you want to fire event after any action is called you have to use action event controller_action_postdispatch_XX_XX_XX

In above section XX_XX_XX is handlename/action of page. You can call any action in pre and post dispatch event for each page.

In your case checkout_index_index handler is used.

Just for example, If you want to do something before checkout cart page is load you have to use event controller_action_predispatch_checkout_cart_index

If you want to do something after checkout cart page is loaded, you need to define controller_action_postdispatch_checkout_cart_index action and set your logic in observer file.