Sitecore Sublayouts rendering on a Sitecore MVC Page (Part 2)

Continued

Control 'ctl01_Button1' of type 'Button' must be placed inside a form tag with runat=server.

Enabling ViewState and PostBacks

1. We need a ViewState provider which is implemented as a hidden input field by the name of "__VIEWSTATE".
2. We need a way to execute an HTTP POST back to the page.
3. The execution of the sublayout/UserControl need access to the request context of the POST so it can process the postback data.

    private static void AddSublayoutToPage(TemplateControl page, string path, string datasource,
        IEnumerable<KeyValuePair<string, string>> parameters)
    {
        var dict = ToDict(parameters);
        var sublayout = CreateSublayout(page, path, datasource, dict);
        var form = CreateForm();
        form.Controls.Add(sublayout);
        page.Controls.Add(form);
    }

    private static HtmlForm CreateForm()
    {
        var formName = GetNextFormName();
        var form = new HtmlForm
        {
            Method = "POST",
            ID = formName,
            Name = formName
        };
        return form;
    }

    private static string GetNextFormName()
    {
        var formNo = 0;
        int countParse;
        if (HttpContext.Current.Items.Contains(CONTEXT_KEY) &&
                int.TryParse(HttpContext.Current.Items[CONTEXT_KEY].ToString(), out countParse))
            formNo = countParse;
        var formName = string.Concat("Form", formNo);
        HttpContext.Current.Items[CONTEXT_KEY] = ++formNo;
        return formName;
    }

public static IHtmlString RenderSitecoreSubLayout(this HtmlHelper html, string path, string datasource = null, RenderingParameters parameters = null)
{
    var page = new DummyPage { ViewStateEncryptionMode = ViewStateEncryptionMode.Never };
    AddSublayoutToPage(page, path, datasource, parameters);
    var result = ExecutePage(page);
    return html.Raw(result);
}

private static string ExecutePage(DummyPage page)
{
    page.ProcessRequest(HttpContext.Current);
    return page.Result;
}

private class DummyPage : Page
{
    public string Result { get; private set; }

    protected override void Render(HtmlTextWriter writer)
    {
        var buffer = new StringWriter();
        var stringWriter = new HtmlTextWriter(buffer);
        base.Render(stringWriter);
        Result = buffer.ToString();
    }
}