Assume we have a $node object and it has some reference field, we get to that field with 

$node->get($field)->referencedEntities();

where we get array of entites we can loop now, se lets say this reference field is even paragraph which has another reference field in it which is taxonomy term, we will loop this field like this

So if you are using entity_create to create new entity programmatically you may also want to have some validations, lets say you implemented that some field is unique and you don't want it to have more then one of the same value and you set that up with   ->addConstraint('UniqueField')

In D7 we used drupal_http_request . to retrieve remote data from other sites and then manipulated in in drupal, well there is no more of that function, we are using HTTP Guzzle from Symfony in drupal8  https://www.drupal.org/node/1862446

Coding a cron job in drupal 8 is pretty easy. All you have to do is go to your module folder, open .module file and add hook_cron function, so lets add some content with our hook_cron

To have integer go to BigInt type you will need to use setSettings in your BaseFieldDefinition for your custom entity, with this you will have space for 19 digits numbers, with unsigned property making this all positive numbers.

Since we already wrote about how to make custom entity(data model) we will want to configure base fields we are adding, first thing you will want is to configure what fields are used for view and form part.

In previous blog post we talked about how to create custom drupal entity(content entity), here are some reasonings when to do such a thing and why.

To create data models like in some other platforms you need to use Content Entity.  Drupal org tutorial about this is broken at this point 18/2018 so use this instead

This solution is useful If you want to have something like standard and premium users and show different content for each role. What we mean here is to show just part of the node for normal user and full node for premium users. So how do we do this? We build 2 different view modes for that node type.

I wont get into how to make custom tokens in drupal 8, look here for that info
https://stefvanlooveren.me/blog/how-create-custom-image-token-drupal-8

Originally you would just put some kind of value like this and have it as plain string