Drupal 8.x

Hi,

Before saving a node with a title, I want to check if the node with given title and language already exists or not. I have seen examples with hook_form_alter(), but I am not following much. And obviously not working. This is what my code looks like:

I have created a menu on Drupal 8 and I want it to display like a collapsible menu. There should be an icon in front of parent links. A click on the icon should open the children's elements, and when it is clicked again, it should close them. However, with the normal meu module, everything is expanded, and I do not know how to make it collapsible. I have tried using jsTree menu as well but I have not been successful either. I wanted to know if there is a module that can do this? Please do note that I am not using Taxonomy to make this menu. Thanks in advance.

In my bartik two columns frontpage, teaser text from each column A post "glues" to the next post's pic (the one in column B). And this is aesthetically unacceptable. 

One way to resolve that, would be to add a tiny (a few pixels wide) white border in each pic, but then the pic moves to the right and I don't like that either.

I believe the right thing to do is create a "corridor" of a few pixels width between the two columns: a space where no letter can go.

I have a module mostly built that provides custom entity access checking via a class inheriting from EntityAccessCheck. The ::access method is called properly and works well in most cases. This module includes a UI that lets an admin specify, for a given entity, what operations are available to each user. The problem is that, if I use ListBuilder::getOperations($entity) and ListBuilder::getDefaultOperations when generating this interface, the ListBuilder class checks what operations the current user has access to. Instead, I need a list of all operations.

Hello, I wanted to know if there was a module that can perform searches on a taxonomy page? Actually, i have a menu with taxonomy terms and the contents of those links are on the taxonomy pages themselves. However, the core search of Drupal does not work on taxonomy, and I am having issues using SearchApi. I hope you could suggest a module that I could use to perform searches on the website that I am developing. Thanks in advance.

I want to display the rendered entity of a group in the TWIG of a node.

In my type of node, I have a field that refers to the rendered entity of the parent group node--article--menu.html.twig :

{{ content.group_content }}

Here is the contents of the TWIG file of the group, the node must render this code without additional markup group--personnel--node-menu.html.twig :