MVC6 TagHelpers with one-time

Question

In older HTML helpers, you can use MVC IDisposableto wrap content - for example, the assistant BeginFormautomatically wrapped it with a *stuff*closing tagform

<% using (Html.BeginForm()) {%>
   *stuff*
<% } %> 

Is it a content wrapper supported with MVC6 TagHelpers? For example, I would like this

<widget-box title="My Title">Yay for content!</widget-box>

to expand into a botstrap widget with a wrapper divs:

<div class="widget-box">
    <div class="widget-header">
        <h4 class="widget-title">My Title</h4>
    </div>
    <div class="widget-body">
        <div class="widget-main">
            Yay for content!
        </div>
    </div>
</div>

Is this possible with TagHelpers?

Solution . I baked @DanielJG the answer to a working demo on github that consumes WidgetBoxTagHelper.cs (will remain valid with Beta / RC / RTM, as I use lib in my working application)

Answer 1

ITagHelper ( @NTaylorMullen, TagHelper - , ), Process ProcessAsync, Dispose.

, , . , widget ( ):

[HtmlTargetElement("widget-box")]
public class WidgetTagHelper : TagHelper
{
    public string Title { get; set; }

    public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
    {
        var outerTag = new TagBuilder("div");
        outerTag.Attributes.Add("class", output.TagName);
        output.MergeAttributes(outerTag);
        output.TagName = outerTag.TagName;

        //Create the header
        var header = new TagBuilder("div");
        header.Attributes.Add("class", "widget-header");
        header.InnerHtml.Append(this.Title);
        output.PreContent.SetHtmlContent(header);

        //Create the body and replace original tag helper content
        var body = new TagBuilder("div");
        body.Attributes.Add("class", "widget-body");
        var originalContents = await output.GetChildContentAsync();
        body.InnerHtml.Append(originalContents.GetContent());
        output.Content.SetHtmlContent(body);
    }
}

:

<widget-box title="My Title">Yay for content!</widget-box>

:

<div class="widget-box">
    <div class="widget-header">My Title</div>
    <div class="widget-body">Yay for content!</div>
</div>

, @addTagHelper _ViewImports.cshtml. , :

@addTagHelper *, WebApplication2

OLD beta7 code

• - [TargetElement].
• TagBuilder SetInnerText, .

:

[TargetElement("widget-box")]
public class WidgetTagHelper : TagHelper
{
    private IHtmlEncoder encoder;
    public WidgetTagHelper(IHtmlEncoder encoder)
    {
        this.encoder = encoder;
    }

    public string Title { get; set; }

    public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
    {
        var outerTag = new TagBuilder("div");
        outerTag.Attributes.Add("class", output.TagName);
        output.MergeAttributes(outerTag);
        output.TagName = outerTag.TagName;

        //Create the header
        var header = new TagBuilder("div");
        header.Attributes.Add("class", "widget-header");
        header.SetInnerText(this.Title);
        output.PreContent.SetContent(header);

        //Create the body and replace original tag helper content
        var body = new TagBuilder("div");
        body.Attributes.Add("class", "widget-body");
        var originalContents = await context.GetChildContentAsync();           
        using (var writer = new StringWriter())
        {
            body.TagRenderMode = TagRenderMode.StartTag;
            body.WriteTo(writer, encoder);
            originalContents.WriteTo(writer, encoder);
            body.TagRenderMode = TagRenderMode.EndTag;
            body.WriteTo(writer, encoder);
            output.Content.SetContent(writer.ToString());
        }                            
    }
}

OLD beta5 code

• InnerHtml.
• -, html, ToHtmlString.

:

[TargetElement("widget-box")]
public class WidgetTagHelper: TagHelper
{
    public string Title { get; set; }

    public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
    {
        var outerTag = new TagBuilder("div");
        outerTag.Attributes.Add("class", output.TagName);
        output.MergeAttributes(outerTag);
        output.TagName = outerTag.TagName;

        //Create the header
        var header = new TagBuilder("div");
        header.Attributes.Add("class", "widget-header");
        header.InnerHtml = this.Title;
        output.PreContent.SetContent(header.ToHtmlString(TagRenderMode.Normal).ToString());

        //Create the body and replace original tag helper content
        var body = new TagBuilder("div");
        body.Attributes.Add("class", "widget-body");
        var originalContents = await context.GetChildContentAsync();
        body.InnerHtml = originalContents.GetContent();
        output.Content.SetContent(body.ToHtmlString(TagRenderMode.Normal).ToString());
    }
}