使用 asp-for 作为参数的自定义 ViewComponent

Custom ViewComponent with asp-for as parameter

我要包装这个:

<textarea asp-for="@Model.Content" ...>

进入可重用的ViewComponent,其中属性将是参数:

<vc:editor asp-for="@Model.Content" />

我能够将 asp-for 作为参数传递给视图组件:

public class EditorViewComponent : ViewComponent
{
    public IViewComponentResult Invoke(ModelExpression aspFor = null)
    {
        //when debugging, aspFor has correct value
        return View(aspFor);
    }
}

但我无法在组件的视图中对其进行评估。这不起作用:

<!-- ViewComponents/Editor/Default.cshtml -->
@model Microsoft.AspNetCore.Mvc.ViewFeatures.ModelExpression
<textarea asp-for="@Model" />

有什么想法吗?

我认为您混合使用了 ViewComponents 和 TagHelpers:https://docs.microsoft.com/en-us/aspnet/core/mvc/views/view-components

查看组件

视图组件在以下事件中被调用:

@await Component.InvokeAsync("EditorView", @Model.Property);
// or
<vc:[view-component-name]>

试试下面的代码片段:

<vc:editor for="@Model.Content" />

标签助手

标签助手只能像这样调用:

<textarea asp-for="@Model.Content">

如果你想将 ModelExpression 传递给底层的 ViewComponent,然后再传递给 TagHelper,你必须使用 @TheModelExpression.Model:

<!-- ViewComponents/Editor/Default.cshtml -->
@model Microsoft.AspNetCore.Mvc.ViewFeatures.ModelExpression
<textarea asp-for="@Model.Model" />

正如@JoelHarkes 所提到的,在这种特殊情况下,自定义标签助手可能更合适。无论如何,我仍然可以在 TagHelper 中呈现 PartialView ala 模板:

[HtmlTargetElement("editor", Attributes = "asp-for", TagStructure = TagStructure.WithoutEndTag)]
public class EditorTagHelper : TagHelper
{
    private HtmlHelper _htmlHelper;
    private HtmlEncoder _htmlEncoder;

    public EditorTagHelper(IHtmlHelper htmlHelper, HtmlEncoder htmlEncoder)
    {
        _htmlHelper = htmlHelper as HtmlHelper;
        _htmlEncoder = htmlEncoder;
    }

    [HtmlAttributeName("asp-for")]
    public ModelExpression For { get; set; }

    [ViewContext]
    public ViewContext ViewContext
    {
        set => _htmlHelper.Contextualize(value);
    }


    public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
    {
        output.TagName = null;

        var partialView = await _htmlHelper.PartialAsync("TagHelpers/Editor", For);

        var writer = new StringWriter();
        partialView.WriteTo(writer, _htmlEncoder);

        output.Content.SetHtmlContent(writer.ToString());
    }
}

.cshtml 模板在 viewcomponent 中看起来完全一样。