Drupal 8.x

I have been working with Drupal 7 for 5-6 years and I have always been very happy that I found Drupal. 

I have two websites running Drupal 7 with no problems. The last couple of years I have tried to learn and use Drupal 8 to see if I could go over with my websites. 

Yesterday, the Bad Sunday, I was watching a webinar about how to use panels and other things in Drupal 8. They said that the distribution Lightning should be something very useful to learn more and understand Drupal 8 better. 

Hi,

I've created a content type for blogs in my site. I would like to add more than one author for each blog. I've created an entity reference field author in 'blog' content type. I would like to show a block of authors in the blog node page.
Any advice is appreciated

I'm trying to create my first model and controller.
The first erors.

Drupal\Component\Serialization\Exception\InvalidDataTypeException: Unable to parse at line 5 (near "'\Drupal\hello_world\Controller\HelloWorldController::HelloWorld'"). in Drupal\Component\Serialization\YamlSymfony::decode() (linea 40 di /home/mt1kibgh/drupal/core/lib/Drupal/Component/Serialization/YamlSymfony.php).

File hello_world.routing.yml

I have a workflow of 3 stages, i create a business rule to hide 2 fields in the stage 1 of workflow   and other business rule to make one field readonly   to apply to stage 2 of workflow.

My problem is that i dont know how apply the business rules to workflow.

My workflow

https://drive.google.com/open?id=1v69OPJdTPfSx3tLPYSPSDYuTIhrB0LFj

My business rules

I create with Profile module two profiles.

In one of that i have a reference to a Paragraph type, and in other a reference to a a content type.

With both i can create contents (with first profile i create paragraphs, with second a content type of course). From the same menu i can delete them, but in reality i can delete only the reference to them, not the nodes.

Now, i want create a view for paragraph or content of a specific profile, but when i do that system show also unreferenced nodes. How can i avoid that?

Hi,

I am new to Drupal development and would like to add a block in to my website to display a custom content type (lets say articles which has an image or is just text) same like as Twitter Block module (that displays twitter feeds).

Is there any such module available?

I should mention that I am using Drupal 8. Any help would be appreciated.

Thanks,