I want wrap this:
<textarea asp-for="@Model.Content" ...>
into reusable ViewComponent, where property will be parameter:
<vc:editor asp-for="@Model.Content" />
I was able to pass asp-for as parameter to the viewcomponent:
public class EditorViewComponent : ViewComponent
{
public IViewComponentResult Invoke(ModelExpression aspFor = null)
{
//when debugging, aspFor has correct value
return View(aspFor);
}
}
But I'm not able to evaluate it in component's view. This does not work:
<!-- ViewComponents/Editor/Default.cshtml -->
@model Microsoft.AspNetCore.Mvc.ViewFeatures.ModelExpression
<textarea asp-for="@Model" />
Any ideas?
I think you are mixing ViewComponents and TagHelpers:https://docs.microsoft.com/en-us/aspnet/core/mvc/views/view-components
View components are invoked in the following matter:
@await Component.InvokeAsync("EditorView", @Model.Property);
// or
<vc:[view-component-name]>
Try the following snippit:
<vc:editor for="@Model.Content" />
the tag helpers are only invoked like this:
<textarea asp-for="@Model.Content">
If you want to pass ModelExpression to underlying ViewComponent and then pass it to TagHelper, you have to do it using @TheModelExpression.Model:
<!-- ViewComponents/Editor/Default.cshtml -->
@model Microsoft.AspNetCore.Mvc.ViewFeatures.ModelExpression
<textarea asp-for="@Model.Model" />
As @JoelHarkes mentioned, in this particular case, custom taghelper could be more appropriate. Anyway, I still can render PartialView ala Template in the TagHelper:
[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());
}
}
the .cshtml template would then look exactly like in viewcomponent.