zainabed.com is collection of programming tutorials, created & maintained by Zainul Abedin Shaikh. These tutorials are predominantly focused on Programming Technology like Java, Java Web,Spring MVC, AngularJs,Elasticsearch, Android, JQuery, Web Design, Mongodb, PHP and MySQL.
MongoDB Aggregation Framework groups set of documents together and performs certain operation on this grouped documents and returns results in the form of documents.
MongoDB aggregation answer to those query which requires grouping of documents.
Aggregation framework works on three type of model
Single Purpose Aggregation Operations
Now let see how MongoDB Aggregation Framework works with simple example.
Suppose you are MongoDB application developer in a respected company and you have been given a MongoDB database that holds information about human population which is distributed according to cities and their states.
What is Abstract Factory design pattern? The intent or definition of Abstract Factory is “ Provide an interface for creating families of related or dependent objects without specifying their concrete classes ” It is kind of an obscure definition, in order to understand it we need to break it into meaningful pieces. 1. " Provide an interface " When we talk about Abstract Factory we talk about interface not abstract class , Basically this design pattern gives us an Interface, like Interface in Java, C# , Typescript (abstract class). Why interface? Whenever we talk about any design pattern, it emphasizes more on how we are going to use it rather than implement it. Interface is always the right type to prefer because concrete class creates tight coupling whereas an interface isolates it from the rest of the system. At runtime we can get different solution, without updating our code. For example interface SecurityFactory