asp.net: dynamic control creation

Sometimes you have to dynamically create controls. For standard elements, everything is simple:

         Label testLabel = new Label ()
         {
             Text = "TEST"
         };
         Page.Controls.Add (testLabel);

This code will add an element of type Label with the text "TEST".
For user items, things are a little more complicated, but also easy.

First, it’s necessary to add a reference to the page to which the control will be added (instead of register, which is used when we add control during design):

 <% @ Reference Control = "~ / ctrls / MyWebCtrl.ascx"%>

Comment: as rightly noted by ostapbender , Reference must be declared when the asp.net site project model is used, if you use the asp.net web application, then such an ad is admissible, but useless because in such a project model, initially all parts work in one namespace and “know” about each other.

Then, to instantiate the class of control in your logic, you need to use LoadControl:

 ctrls_MyWebCtrl ctrl = (ctrls_MyWebCtrl) LoadControl ("~ / ctrls / MyWebCtrl.ascx"); 

Now you can set all the properties of the object or call the necessary methods. The ready control is added to the ControlCollection container on the page; usually, the standard PlaceHolder control is used for this.

 PlaceHolder1.Controls.Add (ctrl); 

One remark, it is recommended to explicitly specify the class name when creating the control:

 <% @ Control ... ClassName = "ctrls_MyWebCtrl"%>

This value will be used in the dynamic creation of the control; if it is not specified, the value will be formed from the name of the control file.
It's all.