great article about Viewstate<\/a>, I wondered if I could do it better now. I worked up a simple example using no Viewstate where values persist across postbacks. Going to the page new resets everything. <\/p>\nThe one piece I don’t like is that it uses session for a control count. But it’s a single Int32 per user that get’s stored in session, so it could be worse. Anyway, here’s the code…<\/p>\n
Note: the aspx page has a placeholder (phOne) and two buttons (btnAdd) and (btnRemove). EnableViewstate is false on phOne.<\/em><\/p>\n\r\nusing System;\r\nusing System.Web.UI;\r\nusing System.Web.UI.WebControls;\r\n\r\nnamespace Web\r\n{\r\n public partial class Dynamic : System.Web.UI.Page\r\n {\r\n private const string KeyNumControls = \"DynamicPage_NumControls\";\r\n private const int DefaultControlCount = 2;\r\n\r\n protected override void OnInit(EventArgs e)\r\n {\r\n CreateControls(NumberOfControls);\r\n base.OnInit(e);\r\n }\r\n\r\n protected override void OnLoad(EventArgs e)\r\n {\r\n if (!Page.IsPostBack)\r\n {\r\n CreateControls(DefaultControlCount);\r\n }\r\n }\r\n\r\n private void CreateControls(int controlCount)\r\n {\r\n NumberOfControls = controlCount;\r\n while(phOne.Controls.Count > NumberOfControls)\r\n {\r\n RemoveLastControl();\r\n }\r\n while(phOne.Controls.Count < NumberOfControls)\r\n {\r\n CreateControl();\r\n }\r\n }\r\n\r\n private void RemoveLastControl()\r\n {\r\n phOne.Controls.RemoveAt(phOne.Controls.Count - 1);\r\n }\r\n\r\n private void CreateControl()\r\n {\r\n phOne.Controls.Add(new TextBox { EnableViewState = false });\r\n }\r\n\r\n protected int NumberOfControls\r\n {\r\n get\r\n {\r\n Session[KeyNumControls] = Session[KeyNumControls] ?? \r\n DefaultControlCount;\r\n return (int)Session[KeyNumControls];\r\n }\r\n set { Session[KeyNumControls] = value; }\r\n }\r\n\r\n protected void BtnAddClick(object sender, EventArgs e)\r\n {\r\n NumberOfControls += 1;\r\n CreateControl();\r\n }\r\n\r\n protected void BtnRemoveClick(object sender, EventArgs e)\r\n {\r\n NumberOfControls -= 1;\r\n RemoveLastControl();\r\n }\r\n }\r\n}<\/code>\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"I worked on a project a couple of years ago using dynamic controls in an Asp.Net WebForms environment. Managing dynamic controls can be a real hassle. So when I read Dave Reed’s great article about Viewstate, I wondered if I could do it better now. I worked up a simple example using no Viewstate where […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23,34,18,24],"tags":[82,69,100],"class_list":["post-236","post","type-post","status-publish","format-standard","hentry","category-aspnet","category-microsoft","category-programming","category-web","tag-asp-net","tag-linkedin","tag-webforms"],"_links":{"self":[{"href":"http:\/\/hoolihan.net\/blog-tim\/wp-json\/wp\/v2\/posts\/236","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/hoolihan.net\/blog-tim\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/hoolihan.net\/blog-tim\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/hoolihan.net\/blog-tim\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/hoolihan.net\/blog-tim\/wp-json\/wp\/v2\/comments?post=236"}],"version-history":[{"count":0,"href":"http:\/\/hoolihan.net\/blog-tim\/wp-json\/wp\/v2\/posts\/236\/revisions"}],"wp:attachment":[{"href":"http:\/\/hoolihan.net\/blog-tim\/wp-json\/wp\/v2\/media?parent=236"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/hoolihan.net\/blog-tim\/wp-json\/wp\/v2\/categories?post=236"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/hoolihan.net\/blog-tim\/wp-json\/wp\/v2\/tags?post=236"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}