ASP.NET Core introductory note 5, entry ASP.NET Core MVC Controller

Excerpt from https://www.cnblogs.com/ken-io/p/aspnet-core-tutorial-mvc-controller-action.html

 

I. Introduction

1, the main content tutorial

• ASP.NET Core MVC Controllers
• ASP.NET Core MVC Controller Operating Guide
• ASP.NET Core MVC controller action return type Introduction Introduction
• ASP.NET Core MVC controller return type operating exemplary Introduction
• ASP.NET Core MVC controller parameters mapping logic Description
• ASP.NET Core MVC controller parameter map / Get Example

2, this tutorial environmental information

Software Environment	Explanation
operating system	Windows 10
SDK	2.1.401
ASP.NET Core	2.1.3
HERE	Visual Studio Code 1.27
Browser	Chrome 69

Benpian the following code to adjust the code: https://github.com/ken-io/asp.net-core-tutorial/tree/master/chapter-02

3, pre-knowledge

You may need to pre-knowledge

• MVC framework / model description

https://baike.baidu.com/item/mvc

Two, ASP.NET Core MVC Controllers

1, ASP.NET Core MVC Controller Overview

In MVC Web framework, the routing module will match the received and forwarded for processing by a corresponding controller (Controller) request.
The role of the controller processing request is received, parses and executes the user input processing corresponding to the program logic, and then returns the corresponding output.

The user input may be QueryString, FormData, may be HTTP Header, HTTP Body.
The controller output format is usually: HTML, JSON, XML, plain text

2, the definition of the controller (Controller) of

All Controller classes must inherit directly or indirectly to Microsoft.AspNetCore.Mvc.ControllerBase. In order to match the view engines, ASP.NET Core MVC framework built  Microsoft.AspNetCore.Mvc.Controllerclass that provides some of the features needed to view engine. So, by default we can extend this class.

3, the controller (Controller) named

Controller class class name (ClassName) recommended to the Controllerending (not case-sensitive).
E.g:

• HomeController
• TestController

Controller routing module is removed as the end of the ControllerName.
Then the corresponding ControllerNameit were Home, Test. This is also the main route mapping to identify the Controller.

Of course, you can not as a controller to Controller class name (ClassName) fixed suffix, then the routing module will be fully qualified class name (ClassName) asControllerName

In ASP.NET MVC framework, the Controller (Controller) Controller to the class name as a suffix must, but this restriction is removed in ASP.NET Core MVC framework.

The following definitions Controller are possible:

//推荐
public class HomeController : Controller { //ControllerName=Home } public class HomeController : BaseController { //ControllerName=Home } public class Test : Controller { //ControllerName=Test } 

Three, ASP.NET Core MVC Controller Operating Guide

1, ASP.NET Core MVC Controller Operations Overview

Controller (Controller) Operation (Action) is after the controller receives a request with the actual method of application processing request / function.

Controller After receiving the request to find a route in accordance with the corresponding ActionName Action, then map the user's input to the Action parameter, after the completion of the final actual execution of Action returns the corresponding output.

2, the controller operation (Action) is defined

Action must be public non-static methods defined in the controller, for example:

public class HomeController : Controller { public IActionResult Index() { return Content("Hello World ！ -ken.io"); } public string Test() { return "test"; } public void DoSomething() { //DoSomething } } 

By default routing configuration:

• Action: Index () response / home / index request
• Action: Test () response / home / test request
• Action: DoSomething () response / home / dosomething request

A public non-static method if you define the Controller, but do not want this method to process the request, it can be marked as NonAction

public class HomeController : Controller { [NonAction] public void LogicMethod(){ } } 

3, the operation controller (Action) Return Type Description

ASP.NET Core MVC Action return type must be defined to achieve the Microsoft.AspNetCore.Mvc.IActionResulttype of interface, the frame itself provides a default implementation of this interface Microsoft.AspNetCore.Mvc.ActionResult, and provides ActionResult class subclasses for different content formats required output.

However, when the method defined Action, return type can also be defined as a string, int, etc., which will return a custom type stream before returning to the response frame is suitable to automatic packaging ActionResult subtypes.

Commonly used ActionResult subclasses described

Action Return Type	Controller built-in method	Explanation
ViewResult	View()	The view of the data referred to Razor view engine rendering
PartialViewResult	PartialView()	The view of the data referred to Razor view engine section view (PartialView) Rendering
ContentResult	Content()	Returns the custom text
JsonResult	Json()	Returns the serialization of the object JSON
file Hunger	File()	Back to be written in response to the binary output
RedirectResult	Redirect()	Redirected to the specified Url
RedirectToRouteResult	RedirectToAction(),RedirectToRoute()	Action or redirected to the specified route
EmptyResult	/	Will be packaged as EmptyResult return null in Action or Action define the return key is void

Four, ASP.NET Core MVC Action exemplary method return type

1, ready to work

New in the Controllers folder ActionResultTestController.csand inherited from the Controller class for testing.

using System;
using Microsoft.AspNetCore.Mvc;

namespace Ken.Tutorial.Web.Controllers { public class ActionResultTestController : Controller { } } 

Configuring the test controller dedicated routing Startup.cs

//配置ActionResult测试专用路由
routes.MapRoute(
    name: "ActionResultTest",
    template: "art/{action}", defaults: new { controller = "ActionResultTest"} ); 

2, ContentResult uses examples

Define the return ContentResult of Action

public IActionResult ContentTest() { return Content("Content Result Test --ken.io"); } 

Startup Items, browser access {host: port} / art / contenttest, see the following output:

ContentResult Test by ken.io

3, JsonResult uses examples

Define the return JsonResult of Action

public IActionResult JsonTest() { return Json(new { Message = "JsonResult Test", Author = "ken.io" }); } 

Startup Items, browser access {host: port} / art / jsontest, see the following output

{
  "message": "JsonResult Test",
  "author": "ken.io" } 

4, FileResult uses examples

Define the return of Action FileResult

public IActionResult FileTest() { var bytes = Encoding.Default.GetBytes("FileResult Test by ken.io"); return File(bytes, "application/text", "filetest.txt"); } 

Startup Items, browser access {host: port} / art / jsontest, will download files filetest.txt.
Contents of the file:

FileResult Test by ken.io

5, Redirect uses examples

Redirect the relevant definition of return Action

public IActionResult RedirectTest() { return Redirect("https://ken.io"); } public IActionResult RedirectToActionTest() { return RedirectToAction("jsontest"); } public IActionResult RedirectToRouteTest() { return RedirectToRoute("Default", new { Controller = "home", Action = "index" }); } 

Start the project browser to access the test:

• Access / art / redirecttest, will jump to  https://ken.io
• Access / art / redirecttoactiontest, will jump to / art / jsontest
• Access / art / redirecttoroutetest, will jump to /

Five, ASP.NET Core MVC Action method parameter mapping example

1, Action parameter map Description

Routing the request corresponding Controller process referred to, will find the corresponding Action Controller method, and from RouteData request data (QueryString, FormData, Header, etc.) or HTTP locate the value required for performing the method parameters.

If the parameter corresponding data is not found, and the parameter type is the type of null, the null value is passed as a parameter to the delivery, otherwise it will lead to a.

Additionally, Action parameter methods may not be defined, from the manual RouteData request data (QueryString, FormData, Header, etc.) or the corresponding HTTP GET parameter values.

2. Preparation

New in the Controllers folder ParamsMappingTestController.csand inherited from the Controller class for testing.

using System;
using Microsoft.AspNetCore.Mvc;

namespace Ken.Tutorial.Web.Controllers { public class ParamsMappingTestController:Controller { } } 

Configuring the test controller dedicated routing Startup.cs

//配置参数映射测试专用路由
routes.MapRoute(
    name: "ParamsMappingTest",
    template: "pmt/{action}/{id?}", defaults: new { controller = "ParamsMappingTest"} ); 

3, an example of basic parameter map

Action Definition receives the routing parameters

public IActionResult GetId(int id) { return Content($"Action params mapping test by ken.io, id:{id}"); } 

? Start the application, browser access / pmt / getid / 1024 or / pmt / getid id = 1024, will see the following output:

Action params mapping test by ken.io, id:1024 

Or increase in the HTTP Header id = 1024 parameters like Tool post PostMan access / pmt / getid and sends a request, will see the same output

4, an example of a mapping array Parameter

Action Definition receiving array parameter

public IActionResult GetArray(string[] id) { var message = "Action params mapping test by ken.io,id:"; if (id != null) { message += string.Join(",", id); } return Content(message); } 

? Application launch, browser access / pmt / getarray / 1,2 or / pmt / getarray id = 1,2, you will see the following output:

Action params mapping test by ken.io,id:1,2 

Or the like accessible via PostMan tool post / pmt / getarray form and set the parameters and sends a request, we will see the same output

5, an example of a custom type of parameter map

Creating Models folder in the project root directory, and create a class file Person.cs

public class Person { public string Name { get; set; } public int Age { get; set; } } 

Receiving a definition of a custom parameter Action

public IActionResult GetPerson(Person person) { return Json(new { Message = "Action params mapping test by ken.io", Data = person }); } 

Application launch, browser access / pmt / getperson name = ken & age = 18, will see the following output?:

{
  "message": "Action params mapping test by ken.io",
  "data": { "name": "ken", "age": 18 } } 

Or access / pmt / getperson by PostMan tool post and the like provided form the parameters and sends a request, you will see the same output

6, an array of custom types exemplary parameter mapping

Receiving a definition of a custom type of array parameter Action

public IActionResult GetPersonList(List<Person> person) { return Json(new { Message = "Action params mapping test by ken.io", Data = person }); } 

Start the application, browser access /pmt/getpersonlist?person[0].name=ken&person[0].age=18&person[1].name=tom&person[1].age=20
will see the following output:

{
  "message": "Action params mapping test by ken.io",
  "data": [ { "name": "ken", "age": 18 }, { "name": "tom", "age": 20 } ] } 

Or the like accessible via PostMan tool post / pmt / getpersonlist form and set the parameters and sends a request, we will see the same output

7, JSON type parameter mapping example

Action Definition type parameter receiving JSON

public IActionResult GetPersonJson([FromBody]Person person) { return Json(new { Message = "Action params mapping test by ken.io", Data = person }); } 

Start the application, this time we can only test the tool by PostMan

First set Content-Type = application / json

JSON then set the parameters and sends a request form, you will see a corresponding output

8, exemplary parameters manually obtain

Defined parameters manually obtain Action

public IActionResult GetByHand() { return Json(new { Id = RouteData.Values["id"], Name = Request.Query["name"] }); } 

? After the application starts, browser access / pmt / getbyhand / 1024 name = ken & name = tom & age = 18
will see the following output:

{
  "id": "1024",
  "name": [ "ken", "tom" ] } 

RouteData.Values [ "id"]: acquiring data from the routing data
Request.Query [ "name"]: Get data from Url parameters
Request.Form [ "name"]: acquiring data from the form parameter