What's the difference between a ViewModel and Controller?

Question

What are the responsibilities of one vs the other? What kind of logic should go in one vs the other? Which one hits services and databases? How do I decide if my code should go in the viewmodel or the controller?

For the record, I am using ASP MVC, but since the question is architectural, I do not believe it matters what language or framework I am using. I'm inviting all MVC to respond

Answer 1

The ViewModel is a Pattern used to handle the presentation logic and state of the View and the controller is one of the fundamentals parts of any MVC framework, it responds to any http request and orchestrates all the subsequent actions until the http response.

The ViewModel Pattern: More info

In the ViewModel pattern, the UI and any UI logic are encapsulated in a View. The View observes a ViewModel which encapsulates presentation logic and state. The ViewModel in turn interacts with the Model and acts as an intermediary between it and the View.

View <-> ViewModel <-> Model 

The Controllers (Comes from the Front Controller Pattern): More Info

It "provides a centralized entry point for handling requests."

HTTP Request -> Controller -> (Model,View) 

--Plain Differences:--

• While the ViewModel is an optional pattern the Controller is a must, if you are going the MVC way.
• The ViewModel encapsulates presentation logic and state, The Controller orchestrates all the Application Flow.