Programmatically load UserControl with reference in web.config

Question

I register usercontrols in Web.config as below. How do i dynamically load usercontrol with tagname header from code-behind into a placeholder? I Use ASP.NET 4.0

<configuration>
  <system.web>
    <pages>
      <controls>
        <add tagPrefix="blogUc" src="~/Controls/Header/Header.ascx" tagName="header"/>
      </controls>
    </pages>
  </system.web>
</configuration>

Answer 1

Here is a good article How to Create Instances of ASP.Net UserControls Programmatically. do not forget to put a reference to the namespace that the UserControl is in in the code-behind file.

// Reference to namespace in Code-Behind file
using MyNamespace.UserControls;

// In code behind class
protected MyUserControl userControl1 = null;

Answer 2

You could programmatically read pages Section from web.config and load the controls you like.

Reference: http://msdn.microsoft.com/en-us/library/system.web.configuration.tagprefixcollection.aspx

Here is the code that might help you. (note- its looping through all Controls collections, which may be a performance problem if you have long list of controls)

PagesSection pagesSection = (PagesSection)WebConfigurationManager.GetWebApplicationSection("system.web/pages");

foreach (TagPrefixInfo tag in pagesSection.Controls)
{
    if (tag.TagName == "header")
    {
        UserControl userControl=  (UserControl) Page.LoadControl(tag.Source);
        PlaceHolder1.Controls.Add(userControl);
        break;
    }
}

Answer 3

Call the TemplateControl.ParseControl method:

Control control = TemplateControl.ParseControl("<blogUc:header runat='server' />");
this.placeHolder.Controls.Add(control);