Observer to alter collection product collection

[morgan_tartreau1]

I've seen we're able to alter the rendering of the result in the product collection thanks to the event

 catalog_block_product_list_collection

I need it (I think) to show only product for a group of users.

My questions are :

1. What does exactly an event (or observer ?) do ?

2. How to use it in order to alter the result of the product collection in the front store ?

[Manthan Dave]

Hi @morgan_tartreau1

1. What does exactly an event (or observer ?) do ?

- RE : In a simple term i would say , when you would like to do your custom actions on before or after the magento's native functionality even you can use event observer , let's say you would like to show a popup when customer is successfully logged in into the system then you can create observer on the event customer_login and then write the code for your popup.

Refer this link for more details - https://devdocs.magento.com/guides/v2.2/extension-dev-guide/events-and-observers.html

2. How to use it in order to alter the result of the product collection in the front store ?

- here i would like to give working example link , refer this - https://magento.stackexchange.com/questions/114207/unable-to-update-product-collection-via-observer-...

Hope it helps !