I've created a template control what I am running into difficults is during the Page_Load event on my web page I cannot access the child controls in the two possible templates. 
What I would like to be able to do is set the value or make some changes to the control at runtime but I have not been successful in gaining code access to the control, for example the TEXTBOX1 control in the EditTemplate template.    
Does anyone know a good way to preform this task, let alone if I am even using the correct event
Example of HTML Render

 <aspSample:TextLabelControl ID="CustTest" runat="server">
<EditTemplate>
   <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
</EditTemplate>
<ViewTemplate>
   <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
</ViewTemplate>
</aspSample:TextLabelControl>
My Test Control Code:
1    using System;
2    using System.ComponentModel;
3    using System.Web.UI;
4    using System.Web.UI.WebControls;
5    using System.Web.UI.Design;
6    
7    
8    
9    namespace Samples.AspNet.CS.Controls.TextLabelControl 
10   {
11       [Designer(typeof(TextLabelControlDesigner)),
12       ToolboxData("&lt;{0}:TextLabelControl runat=server></{0}:TextLabelControl>"),
13      ParseChildren(true)]
14       public sealed class TextLabelControl : WebControl, INamingContainer
15       {
16   
17           // Field for the templates
18   
19           private ITemplate editTemplate;
20           private ITemplate viewTemplate;
21           private Boolean actionControl;
22           private string valueControl;
23           
24   
25           public TextLabelControl()
26           {
27           }
28   
29   [PersistenceMode(PersistenceMode.InnerProperty), 
30   TemplateContainer(typeof(TemplateControl)), 
31   TemplateInstance(TemplateInstance.Single) ]
32   
33           public ITemplate EditTemplate
34           {
35   
36               get { return editTemplate; }
37               set { editTemplate = value; }
38   
39           }
40   
41   [PersistenceMode(PersistenceMode.InnerProperty), 
42   TemplateContainer(typeof(TemplateControl)), 
43   TemplateInstance(TemplateInstance.Single) ]
44   
45           public ITemplate ViewTemplate
46           {
47   
48               get { return viewTemplate; }
49               set { viewTemplate = value; }
50   
51           }
52   
53           public Boolean Edit
54           {
55               get { return actionControl; }
56               set { actionControl = value; }
57           }
58   
59           public string Value
60           {
61               get { return valueControl; }
62               set { valueControl = value; }
63           }
64   
65           protected override void CreateChildControls()
66           {
67   
68               this.Controls.Clear();
69   
70               //EnsureChildControls();
71   
72               ITemplate template;
73   
74               if (actionControl == true)
75               {
76                   template = editTemplate;
77               }
78               else
79               {
80                   template = viewTemplate;
81               }
82   
83               PlaceHolder pan = new PlaceHolder();
84               template.InstantiateIn(pan);
85               this.Controls.Add(pan);
86   
87               //base.CreateChildControls();
88           }
89   
90       }
91   
92   
93       public class TextLabelControlDesigner : ControlDesigner
94       {
95           TemplateGroupCollection col = null;
96   
97           public override void Initialize(IComponent component)
98           {
99               // Initialize the base
100              base.Initialize(component);
101              // Turn on template editing
102              SetViewFlags(ViewFlags.TemplateEditing, true);
103          }
104  
105          // Add instructions to the placeholder view of the control
106          public override string GetDesignTimeHtml()
107          {
108              return CreatePlaceHolderDesignTimeHtml("Click here and use " +
109                  "the task menu to edit the templates.");
110          }
111  
112  
113          public override TemplateGroupCollection TemplateGroups
114          {
115              get
116              {
117  
118                  if (col == null)
119                  {
120                      // Get the base collection
121                      col = base.TemplateGroups;
122  
123                      // Create variables
124                      TemplateGroup tempGroup;
125                      TemplateDefinition tempDef;
126                      TextLabelControl ctl;
127  
128                      // Get reference to the component as TemplateGroupsSample
129                      ctl = (TextLabelControl)Component;
130  
131                      // Create a TemplateGroup
132                      tempGroup = new TemplateGroup("Template Set A");
133  
134                      // Create a TemplateDefinition
135                      tempDef = new TemplateDefinition(this, "Template Edit",
136                          ctl, "EditTemplate", true);
137  
138                      // Add the TemplateDefinition to the TemplateGroup
139                      tempGroup.AddTemplateDefinition(tempDef);
140  
141                      // Create another TemplateDefinition
142                      tempDef = new TemplateDefinition(this, "Template View",
143                          ctl, "ViewTemplate", true);
144  
145                      // Add the TemplateDefinition to the TemplateGroup
146                      tempGroup.AddTemplateDefinition(tempDef);
147  
148                      // Add the TemplateGroup to the TemplateGroupCollection
149                      col.Add(tempGroup);
150  
151                  }
152  
153                  return col;
154              }
155          }
156  
157          // Do not allow direct resizing unless in TemplateMode
158          public override bool AllowResize
159          {
160              get
161              {
162                  if (this.InTemplateMode)
163                      return true;
164                  else
165                      return false;
166              }
167          }
168      }
169  
170  }
171  
 

Hi,
From the code you provided, the code works well. Actually, if you take a look at the custom server control you provided, you can find there’s a active template designed in that control, only if you set the Edit property to true, the EditTemplate will be the active template, otherwise, ViewTemplate is the active one.
So based on the control you provided, you can use it in two ways:
Suppose you have declared your custom server control on aspx page in the following way:
<cc1:TextLabelControl ID="TextLabelControl1" runat="server">
            <EditTemplate>
                    <asp:TextBox ID="textbox1" Text="abc" runat="server"></asp:TextBox>
            </EditTemplate>
            <ViewTemplate>
                    <asp:Label ID="Label" runat="server" Text="Hello"></asp:Label>
            </ViewTemplate>
        </cc1:TextLabelControl>
 Scenario 1: Set Edit property to false (or don’t set the Edit property), the ViewTemplate will actually take effect. 
Label lb = this.TextLabelControl1.FindControl("Label") as Label;
TextBox tb = this.TextLabelControl1.FindControl("textbox1") as TextBox;

Response.Write(tb.Text); // Null exception occurs.
Response.Write(lb.Text); // Output: Hello

Scenario 2: Set Edit property to true, the EditTemplate will actually take effect. 
this.TextLabelControl1.Edit = true;
Label lb = this.TextLabelControl1.FindControl("Label") as Label;
TextBox tb = this.TextLabelControl1.FindControl("textbox1") as TextBox;

Response.Write(tb.Text); // Output: abc
Response.Write(lb.Text); // Null exception occurs.

Thanks.
Michael Jin.
Microsoft Online Community Support

Please remember to mark the replies as answers if they help and unmark them if they provide no help.