HtmlGenericControl(“br”) rendering twice

Question

I'm adding some content to a given web page from code behind. When I want to add a break after some text, I try to do that this way:

pDoc.Controls.Add(New Label With {.Text = "whatever"})
pDoc.Controls.Add(New HtmlGenericControl("br"))

,where pDoc is the Panel in which I'm adding the content. But it adds two br tags into the final HTML.

I've avoid this behaviour this way:

pDoc.Controls.Add(New Label With {.Text = "whatever" & "<br />"})

Anyway, I'm so curious and I want to know why

pDoc.Controls.Add(New HtmlGenericControl("br"))

is acting that way. I also think my approach is not too fancy.

Regards,

Answer 1

After some testing it looks like the reason is that HtmlGenericControl doesn't support self closing. On server side the HtmlGenericControl("br") is treated as:

<br runat="server"></br>

There is no </br> tag in HTML, so the browser shows it as there are two <br /> tags. Nice way out of this is to create HtmlGenericSelfCloseControl like this (sorry for C# code but you should have no issue with rewritting this in VB.NET):

public class HtmlGenericSelfCloseControl : HtmlGenericControl
{
    public HtmlGenericSelfCloseControl()
        : base()
    {
    }

    public HtmlGenericSelfCloseControl(string tag)
        : base(tag)
    {
    }

    protected override void Render(HtmlTextWriter writer)
    {
        writer.Write(HtmlTextWriter.TagLeftChar + this.TagName);
        Attributes.Render(writer);
        writer.Write(HtmlTextWriter.SelfClosingTagEnd);
    }

    public override ControlCollection Controls
    {
        get { throw new Exception("Self closing tag can't have child controls"); }
    }

    public override string InnerHtml
    {
        get { return String.Empty; }
        set { throw new Exception("Self closing tag can't have inner content"); }
    }

    public override string InnerText
    {
        get { return String.Empty; }
        set { throw new Exception("Self closing tag can't have inner text"); }
    }
}

And use it instead:

pDoc.Controls.Add(New Label With {.Text = "whatever"})
pDoc.Controls.Add(New HtmlGenericSelfCloseControl("br"))

As a simpler alternative (if you have reference to the Page) you can try using Page.ParseControl:

pDoc.Controls.Add(New Label With {.Text = "whatever"})
pDoc.Controls.Add(Page.ParseControl("br"))

Answer 2

Actually you can use;

pDoc.Controls.Add(new LiteralControl("<br/>"));

Whereas new HtmlGenericControl("br") adds two <br>, this will only add <br/> tag to your HTML so that you just have 1 space line. In this picture I added those breaks with that code block.

Also similar question here: Server control behaving oddly