MVC Controller

MVC Controller

A controller is responsible for controlling the way that a user interacts with an MVC application.

                

A controller determines what response to send back to a user when a user makes a browser request.

·         It is Just a class that implements IController

·         Use the View Method to display the View.

·         Public methods are the action methods

Explanation: In MVC, we write the code in service oriented pattern. Anything you write as service oriented, every method you write in controller should be public, globally accessed because we will have multiple layers.

·         Apply [NonAction] attribute to turn this off

Explanation:

[NonAction]

Public void Add ()

This method will be public to your project, but not accessible to other project.

·         Invoking via routing mechanisms(**********)

Explanation: MVC says we will have friendly Uri

Uri—uniform resource identifier

Today it is not URL, today they are URI

What is routing:

Is the process where requested URL is mapped to MVC Controller method resulting in the simple URL’S to invoke methods

Aspx request—handler->aspx engine

Webserveràhandleràextensions

Webserver are based on handler and handlers are based on extensions

Routing will do the mapping to webserver understandable format.

How mapping is performed

Based on routing instructions that the developers provide .

In every mvc project ,that we create by default following route instructions is added

Note: By default one route instruction is added.

Where is the route mapping code written?

The route mapping code is written in the “global.asax” file.

Why Routing Instructions

Because mvc works with routing, so we have one routing instruction by default.

E.g.: http://localhost/Demo/Message

Local hostà routing

Is the mediator between webserver handler and URL

For example, consider the following URL:  /Job/Details/3

• This URL is parsed into three parts like this:

Controller = Job Controller

Action = Details & Id = 3

The default route includes default values for all three segments. The default Controller is Home Controller,

The default Action is Index,

And the default Id is an empty string.

Controllers

Core Action Functionality

What are the different types of results in MVC?

In MVC, we will not have the return types as string, int, etc.

Actions methods should return an Action Result

• ViewResult ‐ if you want to show a View

• ContentResult ‐ directly returning content

• RedirectResult to redirect to a new URL

• RedirectToRouteResult ‐ redirect to route

• EmptyResult ‐ null object pattern

• JsonResult ‐ returning a Json

• JavaScriptResult - script that can be executed on the client

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1.    FileContentResult - Returns a file to the client

2.    FileStreamResult - Returns a file to the client, which is provided by a Stream

3.    FilePathResult - Returns a file to the client