.NET Core第31天_Controller Action的各種不同回傳(ContentResult,ViewResult,RedirectResult,RedirectToActionResult,RedirectToRouteResult,FileResult)

.NET Core第31天_Controller Action的各種不同回傳(ContentResult,ViewResult,RedirectResult,RedirectToActionResult,RedirectToRouteResult,FileResult)_part1

- 8月 17, 2021

這裡一樣新增好一個專案

預設建立的專案可以看到每個action 回傳型別都為一個IActionResult的interface，每一個回傳型別都會去實作該介面，有泛型意味。

ContentResult

可以用於指定一班文字回傳或者不同MIME型態的內文

using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;
using Net5AppDiffAction.Models;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;

namespace Net5AppDiffAction.Controllers
{
    public class HomeController : Controller
    {
        private readonly ILogger<HomeController> _logger;

        public HomeController(ILogger<HomeController> logger)
        {
            _logger = logger;
        }

        public IActionResult Index()
        {
            return View();
        }

        public IActionResult Privacy()
        {
            return View();
        }

        [ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
        public IActionResult Error()
        {
            return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
        }


        public ContentResult GreetUser_GeneralStr()
        {
            return Content("Hello world from .net core mvc");
        }

        public ContentResult GreetUser_HTML()
        {
            return Content("<div><b>Hello world from .net core mvc</b></div>","text/html");
        }

        public ContentResult GreetUser_XML()
        {
            return Content("<div><b>Hello world from .net core mvc</b></div>", "text/xml");
        }

    }
}

效果

最常用的

ViewResult

回傳一個畫面

public ViewResult TodoList()
{
    ViewBag.Message = "Todo List test";
    return View();
}

效果

RedirectResult

網頁跳轉

有分兩種一般跳轉(status code:302)

跟永久跳轉(status code:301)

public RedirectResult GotoURL()
{
    return Redirect("http://www.google.com"); //HTTP status code : 302
}

public RedirectResult GotoURLPermanently()
{
    return RedirectPermanent("http://www.google.com"); //HTTP status code : 301
}

永久跳轉(status code:301)

通常若是要轉向到既有的檔案或自己站內的頁面

會建議用永久跳轉，有助於SEO成效。

如果資源已被永久刪除，將不再是先前的位置訪問。大部分Browser

都會緩存此響應並自動執行重定向，而無需再次請求原始資源。

一般跳轉(status code:302)

若想驗證回傳的status code可以下載Fiddler來自行測試

當Press Enter後即可從左側觀察的到status code回傳對應結果

RedirectToActionResult

跳轉到指定的action可傳相應的參數

public ViewResult TodoList(string Message = "Default Message for TodoList Test")
{
    ViewBag.Message = Message;
    return View();
}

public RedirectToActionResult GotoContactsAction()
{
    return RedirectToAction("TodoList", new { Message = "I am coming from a different action..." });
}

效果

RedirectToRouteResult

藉由route的跳轉

在startup.cs中做一些route的設置修改

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace Net5AppDiffAction
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllersWithViews();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }
            app.UseHttpsRedirection();
            app.UseStaticFiles();

            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllerRoute(
                    name: "TodoListRoute",
                    pattern: "GotoAbout",
                    defaults: new { controller = "Home", action = "TodoList" });


                endpoints.MapControllerRoute(
                    name: "default",
                    pattern: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}

這裡在HomeController.cs新增的這個action就是去透過指定route來做相應跳轉

public RedirectToRouteResult GotoAbout()
{
    return (RedirectToRoute("TodoListRoute"));
}

這裡要注意各自對應參數要一致

效果

FileResult

用於文檔下載

public FileResult DownloadFile()
{
    return File("/css/site.css","text/plain","download_newsite.css");
}

public FileResult ShowLogo()
{
    return File("./Images/logo.png","images/png");
}