MVC Core 有没有更好的方法给 _Layout.cshtml 页传递数据

Question

在控制器中这样写

 public async Task< IActionResult > Index()    
{  
    ViewData["Title"] = "未命名";  
    return View();  
 }  

index.cshtml 页面中

@ViewData["Title"] 就可以得到字符 "未命名"

index.cshtml 使用 _Layout.cshtml 页

index.cshtml 可以跳转到 ProductCenter.cshtml 页

ProductCenter.cshtml 使用 _Layout.cshtml 页

public async Task< IActionResult > ProductCenter()    
 {  
       //注释   ViewData["Title"] 后 ProductCenter.cshtml  页无法得到 字符 "未命名"  
       //   ViewData["Title"] = "未命名";             
        return View();  
  }  

如果想每一个页面都可以得到 字符 "未命名" 。

那么每个IActionResult< IActionResult > 都需要有 ViewData["Title"] = "未命名";

这种方法太麻烦，有没有更简单的方法。

Answer 1

Hi @长生猫 ,

You could use session to transfer data from content page to layout page. Please refer the following steps:

1. Configure session state Add a call to AddSession in ConfigureServices
   Add a call to UseSession in Configure.
2. Configure the
   Add a call to AddHttpContextAccessor() in the ConfigureServices: to access HttpContext and access sesson value in the View Page. After the above configuration, the result as below:

   public void ConfigureServices(IServiceCollection services)  
   {  
       services.AddDistributedMemoryCache();  
   
       services.AddSession(options =>  
       {  
           options.Cookie.Name = ".AdventureWorks.Session";  
           options.IdleTimeout = TimeSpan.FromMinutes(10);  
           options.Cookie.HttpOnly = true;  
           options.Cookie.IsEssential = true;  
       });  
       services.AddHttpContextAccessor()  
       //services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();  
       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.UseSession();  
       app.UseEndpoints(endpoints =>  
       {  
           endpoints.MapControllerRoute(  
               name: "default",  
               pattern: "{controller=Home}/{action=Index}/{id?}");  
       });  
   }  
   

3. Set Session value in the Controller:

   public IActionResult Index()  
   {  
       if (string.IsNullOrEmpty(HttpContext.Session.GetString("Title")))  
       {  
           HttpContext.Session.SetString("Title", "Layout Title");  
       }  
       return View();  
   }  
   public IActionResult Privacy()  
   {  
       return View();  
   }  
   

4. Accesss the Session value in the Layout Page: Add the following code in the head:

   @using Microsoft.AspNetCore.Http  
   @inject IHttpContextAccessor HttpContextAccessor    
   

   Add the following code in the body:

   @if (!string.IsNullOrEmpty(HttpContextAccessor.HttpContext.Session.GetString("Title")))  
   {  
       var value = HttpContextAccessor.HttpContext.Session.GetString("Title");  
       <span>@value</span>  
   }  
   

The result as below: In the Index Action method, we set the session value, in the Privacy action method, there is no need to set session value again.

[Note]

• In the above sample, we are using session to store the value, please pay more attention to the Session Expired time. More detail information, see Session state.
• Currently in Microsoft Q&A we only support English, could you please edit your question into English? Thanks for your understanding.

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Best Regards,
Dillion