We will create a filter that filters a node which is the latest one created. This is interesting when used in connection with other filters especially taxonomy term for a specific vocabulary. For example show me all articles with term Backend except the latest one with any term in the vocabulary. 

Let's explain it further, I have a vocabulary Articles which contains terms (Backend, Frontend & DevOps). When I create a new article I can assign one or more terms to it since some articles may belong to multiple terms like both Backend & Frontend and so on.

Now I want to show the latest article on front page which is easy to achieve using the existing Views filters (Authored on field) and limit result to one. But I don't want to show this latest article in any list of Backend, Frontend or DevOps since this has been already shown on front page and I don't want a duplicate link/article.

Now a million dollar comment is that the Backend list doesn't know if the latest article on front page is selected from this list or not and so are Frontend & DevOps lists. They are simply filtered on corresponding taxonomy terms (backend, frontend, devops). 

In simple words and yet in simple SQL this is the problem of sub-query i.e first we find the latest article with a sub-query and then filter it in the main query like nid != latest article id.

A pseudo code would look something like the following: 

SELECT * FROM CONTENT_TYPES
WHERE field_tags  = Backend
AND NID != ( SELECT NID FROM CONTENT_TYPES ORDER BY authored_on DESC LIMIT 1);

In this article I would like to create a simple Drupal ( MVC ) module. The big question here is how to resize an image to user required size. Well we can do so by creating an Image style in Drupal and can choose it for any rendering image. That works but we can create a limited number of image sizes/styles this way.

I wanted to have a plethora of image sizes available to users for example ranging from 16 pixels to 4800 pixel and this would result in 22 million different styles which is not feasible using Drupal GUI Image styles.

At the same time I wanted to use the Drupal builtin modules for Image Styles and Image Effects. Hence I ended up with creating/configure the image styles on the fly (at run time). This way we don't need to save any of the image style in Drupal DB.

The user simply asks for a dimension, our module will create an object (OOP), resize it and then provide that image to the user through the API.

In this article we will mention the most important functions that Drupal provides out of the box.