form action using ASP AJAX Extensions

Staffan Eketorp

Vote:

As a user of EPiServer CMS you may have noticed that a lot of magic happens in a html rewrite filter. This filter never kicks in if you use update panels and ASP AJAX Extensions. Maybe you could live with not having nice links, but having the form action attribute erronously rewritten is a disaster. To overcome this limitation, here's a tip: use a control adapter for HtmlForm. This can look like the following In file HtmlFormAdapter.cs


namespace MyNamespace
{
    public class HtmlFormAdapter : ControlAdapter
    {
        protected override void Render(HtmlTextWriter writer)
        {
            HtmlForm form = Control as HtmlForm;
            if (form == null)
                throw new Exception("HtmlFormAdapter must be used to render a form. Check your .browser file adapter mappings");

            writer.WriteBeginTag("form");

            writer.WriteAttribute("name", form.Name);
            writer.WriteAttribute("method", form.Method);

            foreach (string key in form.Attributes.Keys)
                writer.WriteAttribute(key, form.Attributes[key]);

            writer.WriteAttribute("action", HttpContext.Current.Request.RawUrl);

            if (form.ID != null)
                writer.WriteAttribute("id", form.ClientID);

            writer.Write(HtmlTextWriter.TagRightChar);

            RenderChildren(writer);

            writer.WriteEndTag("form");
        }
    }
}

and in your ~/App_Browsers/AdapterMappings.browser file

#17710

Oct 05, 2007 10:53

Vote:

Thanks a bunch! This enabled us to drop a lot of less pretty workarounds! :) /Ted

#18543

Oct 05, 2007 14:06

Vote:

This solution seems to be causing a "Validation of viewstate MAC failed.." error. Not sure why, though.

#18544

Oct 06, 2007 16:48

Staffan Eketorp

Vote:

Try this code instead....my guess it is due to attributes getting removed from the original HtmlForm implementation and thus not being included in viewstate. This code ressembles the original code much more...


        protected override void Render(HtmlTextWriter writer)
        {
            HtmlForm form = Control as HtmlForm;
            if (form == null)
                throw new Exception("HtmlFormAdapter must be used to render a form. Check your .browser file adapter mappings");

            writer.WriteBeginTag("form");

            RenderAttributes(writer);

            writer.Write(HtmlTextWriter.TagRightChar);

            RenderChildren(writer);

            writer.WriteEndTag("form");
        }

        protected void RenderAttributes(HtmlTextWriter writer)
        {
            HtmlForm form = Control as HtmlForm;
            Page page = this.Page;

            if (form == null)
                throw new Exception("HtmlFormAdapter must be used to render a form. Check your .browser file adapter mappings");

            if (page == null)
                throw new Exception("HtmlFormAdapter must be used to render a form that is placed on a Page");

            writer.WriteAttribute("method", form.Method);
            form.Attributes.Remove("method");
            writer.WriteAttribute("action", HttpContext.Current.Request.RawUrl, true);
            form.Attributes.Remove("action");


            if (this.Browser.EcmaScriptVersion.Major > 0)
            {
                //Handle onSubmit scripts
                string clientOnSubmitEvent = "return typeof(WebFormOnSubmit) != 'undefined') ? WebForm_OnSubmit() : true;";
                string onSubmit = form.Attributes["onsubmit"];
                if (!string.IsNullOrEmpty(onSubmit))
                {
                    if (!onSubmit.EndsWith(";"))
                        onSubmit += ";";
                    page.ClientScript.RegisterOnSubmitStatement(typeof(HtmlForm), "OnSubmitScript", onSubmit);
                    form.Attributes.Remove("onsubmit");
                }
                
                writer.WriteAttribute("onsubmit", clientOnSubmitEvent);

                //Handle default button scripts
                if (!string.IsNullOrEmpty(form.DefaultButton))
                {
                    Control button = form.FindControl(form.DefaultButton);
                    if ((button == null) && (this.Page != null))
                    {
                        if (form.DefaultButton.IndexOfAny(new char[] { '$', ':' }) != -1)
                        {
                            button = this.Page.FindControl(form.DefaultButton);
                        }
                    }
                    if (!(button is IButtonControl))
                    {
                        throw new InvalidOperationException("Only controls that implement IButtonControl can be default buttons.");
                    }
                    
                    writer.WriteAttribute("onkeypress", "return WebForm_FireDefaultButton(event, '" + button.ClientID + "')");
                }
            }

            if (form.ID != null)
                writer.WriteAttribute("id", form.ClientID);

            form.Attributes.Render(writer);
        }

#18545

Oct 08, 2007 10:58

Staffan Eketorp

Vote:

If you don't want the script for onsubmit to work, you can of course ommit the printout (at least according to some conditions of yours). Meybe you don't care about default button behaviour. If so just remove that part

#18546

Oct 08, 2007 10:59

Staffan Eketorp

Vote:

I saw there was an error in the javascript in the middle of RenderAttributes...should be


        protected void RenderAttributes(HtmlTextWriter writer)
        {
            HtmlForm form = Control as HtmlForm;
            Page page = this.Page;

            if (form == null)
                throw new Exception("HtmlFormAdapter must be used to render a form. Check your .browser file adapter mappings");

            if (page == null)
                throw new Exception("HtmlFormAdapter must be used to render a form that is placed on a Page");

            writer.WriteAttribute("method", form.Method);
            form.Attributes.Remove("method");
            writer.WriteAttribute("action", HttpContext.Current.Request.RawUrl, true);
            form.Attributes.Remove("action");


            if (this.Browser.EcmaScriptVersion.Major > 0)
            {
                //Handle onSubmit scripts
                string clientOnSubmitEvent = "return (typeof(WebForm_OnSubmit) != 'undefined') ? WebForm_OnSubmit() : true;";
                string onSubmit = form.Attributes["onsubmit"];
                if (!string.IsNullOrEmpty(onSubmit))
                {
                    if (!onSubmit.EndsWith(";"))
                        onSubmit += ";";
                    page.ClientScript.RegisterOnSubmitStatement(typeof(HtmlForm), "OnSubmitScript", onSubmit);
                    form.Attributes.Remove("onsubmit");
                }
                
                writer.WriteAttribute("onsubmit", clientOnSubmitEvent);

                //Handle default button scripts
                if (!string.IsNullOrEmpty(form.DefaultButton))
                {
                    Control button = form.FindControl(form.DefaultButton);
                    if ((button == null) && (this.Page != null))
                    {
                        if (form.DefaultButton.IndexOfAny(new char[] { '$', ':' }) != -1)
                        {
                            button = this.Page.FindControl(form.DefaultButton);
                        }
                    }
                    if (!(button is IButtonControl))
                    {
                        throw new InvalidOperationException("Only controls that implement IButtonControl can be default buttons.");
                    }
                    
                    writer.WriteAttribute("onkeypress", "return WebForm_FireDefaultButton(event, '" + button.ClientID + "')");
                }
            }

            if (form.ID != null)
                writer.WriteAttribute("id", form.ClientID);

            form.Attributes.Render(writer);
        }

#18547

Oct 10, 2007 9:55

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form action using ASP AJAX Extensions