Question

Software Engineering

1. How are controller actions triggered?

Answer 1

A controller is used to define and group a set of actions. An action (or action method) is a method on a controller which handles requests. Controllers logically group similar actions together. This aggregation of actions allows common sets of rules, such as routing, caching, and authorization, to be applied collectively.

Public methods on a controller, except those with the [NonAction] attribute, are actions. Parameters on actions are bound to request data and are validated using model binding. Model validation occurs for everything that's model-bound. The ModelState.IsValid property value indicates whether model binding and validation succeeded.

Action methods should contain logic for mapping a request to a business concern. Business concerns should typically be represented as services that the controller accesses through dependency injection. Actions then map the result of the business action to an application state.

Actions can return anything, but frequently return an instance of IActionResult (or Task<IActionResult> for async methods) that produces a response. The action method is responsible for choosing what kind of response. The action result does the responding.