How to change <link> tag in the page source on server side?

Question

So, I have a detail page for a tridion site which has a url of the form : www.abc.com.detail.aspx/1234 which is a dynamic page and 1234 here is the id of the component which the page is rendering. Now, I need to build canonical tag for the same in the page source. Currently, I am making the tag with 'href' as: www.abc.com.detail.aspx in the page source by taking the publish location of the page in its page template, but i want to show the complete url along with its ID to be rendered in the page source on the run time.

I have used jquery in my page's user control but that would only help modifying the tag on client side.

What would be the best way to implement this?

Answer 1

In case of Dynamic page, There's not much you can do from CMS side.You can use below sample:

using System.Web.UI.HtmlControls;

HtmlLink canonicalLink = new HtmlLink();
canonicalLink.Attributes.Add("rel", "canonical");

string absolutePath = Request.Url.AbsolutePath.ToLower();
//The default.aspx should not be present in the canonical Url.
 if (absolutePath.Contains("default.aspx"))
       {
         absolutePath = absolutePath.Replace("default.aspx", string.Empty);
       }
  canonicalLink.Attributes.Add("href", (CheckSecureRequest() ? "https://" :
                            "http://") + Request.Url.Host + absolutePath);


// Add the tag to Page header, ID=Head1
      this.Head1.Controls.Add(canonicalLink);

You need to set the value of absolutePath as per your own requirement.

Also, in case of a static page in CMS, you can achieve something similar as below:

1.) Add the below code in Page's DWT. Use a metadata schema for every page. Here I was using a schema with field CustomCanonicalURL where I used to set the URL just in case it has something to be completely different.

<!-- TemplateBeginIf cond="(Page.Metadata.CustomCanonicalURL!='')" -->
 <input type="hidden" id="hdnCustomCanonicalUrl"
       value="@@Page.Metadata.CustomCanonicalURL@@" runat="server" />
<!-- TemplateEndIf -->

Now read the value of this hidden field again at runtime:

 HtmlInputHidden hdnCustomCanonicalUrl = null;
 string CustomCanonicalUrl = string.Empty;
 ContentPlaceHolder headContentPlaceHolder = (ContentPlaceHolder)this.Page.Master.FindControl("pageContent");

if (headContentPlaceHolder != null)
 {
    hdnCustomCanonicalUrl = (HtmlInputHidden)headContentPlaceHolder.FindControl("hdnCustomCanonicalUrl");
 if (hdnCustomCanonicalUrl != null)
      {
         if (!string.IsNullOrEmpty(hdnCustomCanonicalUrl.Value))
               {
                 CustomCanonicalUrl = hdnCustomCanonicalUrl.Value;
               }
      }
 }

   HtmlLink canonicalLink = new HtmlLink();
   canonicalLink.Attributes.Add("rel", "canonical");
   if (!string.IsNullOrEmpty(CustomCanonicalUrl))
   canonicalLink.Attributes.Add("href", CustomCanonicalUrl);

[ All the above .NET code were placed in the master file with the names for ContentPlaceholder you can simply guess from above sample. The corresponding Content controls were simply placed in Page's DWT . ]