Question

是否可以从控制器调用View Component并将其渲染为字符串？我真的在寻找一些代码示例。任何帮助将不胜感激。

Answer 1

从beta7开始，现在可以直接从控制器返回ViewComponent。检查the announcement

的MVC / Razor部分

MVC中的新ViewComponentResult可以轻松返回结果来自动作的ViewComponent。这样可以轻松曝光 ViewComponent的逻辑作为独立端点。

所以现在返回示例视图组件的代码只需要：

public class HomeController : Controller
{
    public IActionResult Index()
    {
        return ViewComponent("My");
    }
}

Answer 2

你可以这样做但你必须应用以下内容，因为它是由DefaultViewComponentHelper渲染的。

您必须创建此实例并创建您需要IViewComponentSelector和IViewComponentInvokerFactory。

要做到这一点，我做了以下事情。

public class HomeController : Controller
    {
        Microsoft.AspNet.Mvc.DefaultViewComponentHelper helper = null;
        Microsoft.AspNet.Mvc.Razor.RazorView razorView = null;
        public HomeController(IViewComponentSelector selector,IViewComponentInvokerFactory factory,IRazorPageFactory razorPageFactory,IRazorPageActivator pageActivator,IViewStartProvider viewStartProvider)
        {
            helper = new DefaultViewComponentHelper(selector, factory);
            razorView = new Microsoft.AspNet.Mvc.Razor.RazorView(razorPageFactory, pageActivator, viewStartProvider);           
        }
        public IActionResult Index()
        {                  
            ViewContext context = new ViewContext(ActionContext, razorView, ViewData, null);
            helper.Contextualize(context);
            string st1 = helper.Invoke("My", null).ToString();
            return View();
        }
}

以下是我的示例View Component。

 public class MyViewComponent : ViewComponent
    {     

        public MyViewComponent()
        {

        }

        public IViewComponentResult Invoke()
        {
            return Content("This is test");
        }
    }

Answer 3

请参阅official ASP.NET article on ViewComponent

中的示例

在他们的示例中，视图组件直接从控制器调用，如下所示：

public IActionResult IndexVC()
{
    return ViewComponent("PriorityList", new { maxPriority = 3, isDone = false });
}

Answer 4

这是我创建的标记帮助程序，用于通过HTML语法嵌入组件。从这样的TagHelper调用应该与Controller的调用紧密匹配。

ViewComponent Tag Helper

using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewComponents;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using Microsoft.AspNetCore.Razor.TagHelpers;


namespace TagHelperSamples.Web
{
    [HtmlTargetElement("component")]
    public class ComponentTagHelper : TagHelper
    {
        private DefaultViewComponentHelper _componentHelper;

        [HtmlAttributeName("name")]
        public string Name { get; set; }

        [HtmlAttributeName("params")]
        public object Params { get; set; }

        [ViewContextAttribute] // inform razor to inject
        public ViewContext ViewContext { get; set; }

        public ComponentTagHelper(IViewComponentHelper componentHelper)
        {
            _componentHelper = componentHelper as DefaultViewComponentHelper;
        }

        public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
        {       
            _componentHelper.Contextualize(ViewContext);

            output.Content.AppendHtml(
                await _componentHelper.InvokeAsync(Name, Params)
            );
        }
    }
}

<强>用法

<component name="RecentComments" params="new { take: 5, random: true }"></component>

Answer 5

来自dotnetstep的代码更新了MVC 6.0.0-beta4（VS2015 RC）：

public class HomeController : Controller
    {
        Microsoft.AspNet.Mvc.ViewComponents.DefaultViewComponentHelper helper = null;

        public HomeController(IViewComponentDescriptorCollectionProvider descriptorProvider, IViewComponentSelector selector, IViewComponentInvokerFactory invokerFactory)
        {
            helper = new DefaultViewComponentHelper(descriptorProvider, selector, invokerFactory);
        }
        public IActionResult Index()
        {                  
            ViewContext context = new ViewContext(ActionContext, null, ViewData, null, null);
            helper.Contextualize(context);
            string st1 = helper.Invoke("My", null).ToString();
            return View();
        }
}

如何从控制器调用View组件

5 个答案: