How can you use MVVM patterns to develop more efficient web applications?

MVVM enforces a clear separation of concerns within your application. The Model represents the data and business logic, the View handles the presentation and user interface, and the ViewModel acts as an intermediary to connect the Model and View. This separation makes it easier to manage, test, and maintain different aspects of your application.

If you’re accustomed to MVC (Model, View, Controller) it may be helpful to map it to MVVM as follows: Model is more or less the same. It’s not user-facing, it’s usually optimized for persistence. Think database rows. Views in MVVM are akin to a union of MVC Views + MVC Controllers: interactive user facing components for both presentation and interaction. ViewModels don’t really map to MVC. If you’re old school you may have heard of “beans”. Often it’s useful to populate your front-end view template with an object that has a different schema than your database models. ViewModels are where this translation between back-end and front-end data happens.

MVVM was introduced (mostly) to fight Java EE and other server side rendering technologies. One of the most famous footers in Java EE forums of all times was something like: "Java EE was sexy until we finally realized that sending html formatted strings to browsers was not that sexy at all". MVVM and data binding was the new thing. Instead of sending a pre-formatted thing into browser, you'd send an object and a template how to render that object. Also, the template contained not only directions how to render, but also how to interact. This was the main division from old school server side things.

MVVM also contributes to improved code reusability and maintainability. By separating the concerns into distinct layers, it promotes a clear separation of responsibilities, making it easier to understand and modify individual components. Additionally, MVVM facilitates easier unit testing, as the view model can be tested independently from the view layer. Overall, MVVM is a powerful design pattern that enhances the development process and promotes cleaner, more efficient code.

Model:- Holds the data. View:- To receive data from View Model and UI Operation. View Model:- Never knows what view does, all business logic goes here. So easy to write the testable code for your logic.

One of the key benefits of MVVM is its ability to reduce code complexity and dependencies by meticulously separating the concerns of each layer. This not only enhances the readability of our code but also makes it more maintainable and scalable. This is a crucial aspect to consider, as it directly impacts the efficiency of our development team and the long-term sustainability of our product.

From a development and testing perspective, MVVM offers a remarkable advantage by providing the flexibility to use different tools and frameworks for each layer. This enables our team to leverage the strengths of popular technologies such as Angular, React, or Vue for the view layer, and .NET, Java, or Python for the model layer. This adaptability not only enhances the developer experience but also opens up opportunities for innovation and staying current with industry trends.

MVVM has several benefits, some of them are mentioned below Separation of Concerns: MVVM divides code into Model (data), View (UI), and ViewModel (presentation logic). Testability: Components can be tested independently, enhancing unit testing. Code Reusability: ViewModel's business logic can be reused across different Views. Maintainability: Clear structure facilitates easy understanding, modification, and extension. Data Binding: Enables automatic synchronization between View and ViewModel. Scalability: Suitable for both small and large projects due to its modular nature. Ease of Maintenance: Changes to UI or logic don't strongly affect each other.

The key advantage of MVVM over MVC and MVP is that it introduces an observable patten which separates the model from the view completely and uses notifications to alert on data changes. Along with the other benefits mentioned, this also results in cleaner dependencies, unidirectional communication and two-way data binding.

Using the MVVM design pattern promotes a clear separation of labor among different roles within a development team, supports robust unit testing by decoupling the UI from the logic, and, through data binding. MVVM helps to minimize boilerplate synchronization code. This separation enables designers to focus on UI improvements without needing a deep understanding of the model, which can significantly improve the user experience. MVVM's emphasis on loose coupling and reusability of components further streamlines development, making it a go-to choice for complex applications with dynamic user interfaces.

There are plenty of third-party frameworks available to provide MVVM support in web, mobile, and desktop. If you are new to MVVM and do not want to roll your own framework, do some research into these available frameworks and begin there. Once you are familiar with how MVVM is implemented in solutions, you can then make a decision if the third-party framework is sufficient or if you need to enhance or create your own support structure.

First question that I would ask is "Should you use MVVM"? And if your answer is yes, then how would you map it to modern distributed, autoscaling app that in best cases is a web assembly in your browser? If wasm, then we're back in the early 2000's and we can think of MVVM. And actually, most frameworks delivering WASM operate in this approach directly. I'm a fan of Blazor from MS. Every component has its internal model, or can be fed a model to render. If I had to guess, Steve Sanderson has something to do with Blazor since I'm seeing a lot of references from the good old Knockout days, when jQuery still was the king. Knockout was one of the AngularJS competitors back in a day to promote MVVM in javascript apps.

As long as you are using a framework it doesn't really matter which one, just pick one you like working in. The larger the community the easier it will be to find examples, packages and support. I have used Angular, React, Vue.js as well as a few others. Since we have developed a strong preference for Typescript, React and Angular are our top choices as they both have built in support for Typescript.

Depending on your solution, it can make a difference which framework you start with. Be sure to research each framework and select one that meets the needs of your requirement. Picking the wrong framework can be a costly mistake. Libraries and capabilities really do matter in MVVM.

From Microsoft, you can try WPF or the present UWP can get you pretty well up to speed with MVVM. The Silverlight/XAML era data binding is still there. The engine luckily, has changed. But. You can see MVVM in Modern Angular as well. Equally in React. You fetch something from the server. That being your Model. Then you turn it aroung with some metadata into to a ViewModel and data-bind it with some dark witchcraft and black magic into View which suprisingly shows you smiles up or smiles down depending on your inputs. Without actually writing a line of code that tells your browser to do so, it's pretty fair to call it `magic`.

If you really want to learn in-depth then you should take a formal class. If you are seeking knowledge, use sites like Pluralsight, LinkedIn learning and many others that provide short learning path videos on this topic and many others. I'm still a book junkie so I tend to buy a good book on my the topic. I like paper and I learn best when I can bend pages, highlight and markup with my pen and highlighter areas. Do what helps you learn the best and then spend hours actually hands on trying it out.

While MVVM brings technical advantages, it's essential to consider the specific requirements of your project and the frameworks or platforms you are working with. The choice of architectural pattern should align with the goals and constraints of your application development.

MVVM is just one of many design patterns. I would recommend picking up a book on software design patterns to learn about other patterns that can make your software solution more maintainable, scalable, and efficient.

I worked in a role in the past where testability was really important to us. But our application was being developed on a closed system with poor support for UI testing. Using MVVM, we were able to get as close as possible to UI testing using TDD and BDD against the View Models. This improved the code coverage and overall quality of our application.

View-Model and Controller are not all that different in reality. All that's changed here is that the logic for constructing and mapping the data to the view is inside the view-model. You still have to query the database, you still have to have try/catch blocks around datalayer objects. You still have to test all of this. It doesn't matter which architecture you use, whether mvc or mvvm or some other mv*, you will always be dealing with the same problems as always: accessing the database, loading the records, handling exceptions, and mapping the data to the view. Most performance issues come from poorly written datalayer objects with poor try/catch structures.

MVVM is powerful, but may be overkill for small applications. Despite what the article here suggests, MVVM is not specific to web development, it's a general purpose design pattern and can be used for web, desktop and mobile development. It is heavily used by Xamarin.Forms, .NET MAUI and Windows Presentation Foundation (WPF).