C# – Render Self-Closing Tag in ASP.NET custom control derived from Control

asp.netccustom-server-controlsfacebook

I'm working on a Facebook FBML controls library and would like to create my FBML controls somewhat patterned like the ASP.NET WebControls library. I have a base class that handles rendering by default; here's my render method:


        protected override void Render(HtmlTextWriter writer)
        {
            AddAttributesToRender(writer);

            if (UseXfbmlSemantics)
            {
                writer.RenderBeginTag(ElementName);
                writer.EndRender();
                writer.RenderEndTag();
            }
            else
            {
                writer.RenderBeginTag(ElementName);
                writer.RenderEndTag();
            }
        }

What I would like is for the rendering to be modified based on UseXfbmlSemantics – if it's true, it should render, for instance:

<fb:name uid="10300399458"></fb:name>

When it's false, it should render with a self-closing tag:

<fb:name uid="10300399458" />

I can get the "true" condition to work almost correctly, but the self-closing tag seems to be incompatible with the Render- set of methods. Unfortunately if that's the case it also means that the AddAttributesToRender pattern wouldn't work, either. What it's actually producing is this:


        <fb:name uid="10300399458">

        </fb:name>

How can I get HtmlTextWriter (or which HtmlTextWriter do I need to use) to make it render a self-closing tag? Or, at the very least, how can I make it not render that interim space (so that the opening and closing tags are immediately next to one another)?

Best Answer

Since this is the top SO question that comes up when searching for "HtmlTextWriter self closing tag", this is for anyone coming here that wants to know how to do it:

writer.WriteBeginTag("tag");
writer.WriteAttribute("attribute", "attribute value");
// ... add other attributes here ...
writer.Write(HtmlTextWriter.SelfClosingTagEnd);

For MVC v5.1 use Html.EnumDropDownListFor

@Html.EnumDropDownListFor(
    x => x.YourEnumField,
    "Select My Type", 
    new { @class = "form-control" })

For MVC v5 use EnumHelper

@Html.DropDownList("MyType", 
   EnumHelper.GetSelectList(typeof(MyType)) , 
   "Select My Type", 
   new { @class = "form-control" })

For MVC 5 and lower

I rolled Rune's answer into an extension method:

namespace MyApp.Common
{
    public static class MyExtensions{
        public static SelectList ToSelectList<TEnum>(this TEnum enumObj)
            where TEnum : struct, IComparable, IFormattable, IConvertible
        {
            var values = from TEnum e in Enum.GetValues(typeof(TEnum))
                select new { Id = e, Name = e.ToString() };
            return new SelectList(values, "Id", "Name", enumObj);
        }
    }
}

This allows you to write:

ViewData["taskStatus"] = task.Status.ToSelectList();

by using MyApp.Common

Asp.net-mvc – ASP.NET MVC – Set custom IIdentity or IPrincipal

Here's how I do it.

I decided to use IPrincipal instead of IIdentity because it means I don't have to implement both IIdentity and IPrincipal.

Create the interface

interface ICustomPrincipal : IPrincipal
{
    int Id { get; set; }
    string FirstName { get; set; }
    string LastName { get; set; }
}

CustomPrincipal

public class CustomPrincipal : ICustomPrincipal
{
    public IIdentity Identity { get; private set; }
    public bool IsInRole(string role) { return false; }

    public CustomPrincipal(string email)
    {
        this.Identity = new GenericIdentity(email);
    }

    public int Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

CustomPrincipalSerializeModel - for serializing custom information into userdata field in FormsAuthenticationTicket object.

public class CustomPrincipalSerializeModel
{
    public int Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

if (Membership.ValidateUser(viewModel.Email, viewModel.Password))
{
    var user = userRepository.Users.Where(u => u.Email == viewModel.Email).First();

    CustomPrincipalSerializeModel serializeModel = new CustomPrincipalSerializeModel();
    serializeModel.Id = user.Id;
    serializeModel.FirstName = user.FirstName;
    serializeModel.LastName = user.LastName;

    JavaScriptSerializer serializer = new JavaScriptSerializer();

    string userData = serializer.Serialize(serializeModel);

    FormsAuthenticationTicket authTicket = new FormsAuthenticationTicket(
             1,
             viewModel.Email,
             DateTime.Now,
             DateTime.Now.AddMinutes(15),
             false,
             userData);

    string encTicket = FormsAuthentication.Encrypt(authTicket);
    HttpCookie faCookie = new HttpCookie(FormsAuthentication.FormsCookieName, encTicket);
    Response.Cookies.Add(faCookie);

    return RedirectToAction("Index", "Home");
}

Global.asax.cs - Reading cookie and replacing HttpContext.User object, this is done by overriding PostAuthenticateRequest

protected void Application_PostAuthenticateRequest(Object sender, EventArgs e)
{
    HttpCookie authCookie = Request.Cookies[FormsAuthentication.FormsCookieName];

    if (authCookie != null)
    {
        FormsAuthenticationTicket authTicket = FormsAuthentication.Decrypt(authCookie.Value);

        JavaScriptSerializer serializer = new JavaScriptSerializer();

        CustomPrincipalSerializeModel serializeModel = serializer.Deserialize<CustomPrincipalSerializeModel>(authTicket.UserData);

        CustomPrincipal newUser = new CustomPrincipal(authTicket.Name);
        newUser.Id = serializeModel.Id;
        newUser.FirstName = serializeModel.FirstName;
        newUser.LastName = serializeModel.LastName;

        HttpContext.Current.User = newUser;
    }
}

Access in Razor views

@((User as CustomPrincipal).Id)
@((User as CustomPrincipal).FirstName)
@((User as CustomPrincipal).LastName)

and in code:

    (User as CustomPrincipal).Id
    (User as CustomPrincipal).FirstName
    (User as CustomPrincipal).LastName

I think the code is self-explanatory. If it isn't, let me know.

Additionally to make the access even easier you can create a base controller and override the returned User object (HttpContext.User):

public class BaseController : Controller
{
    protected virtual new CustomPrincipal User
    {
        get { return HttpContext.User as CustomPrincipal; }
    }
}

and then, for each controller:

public class AccountController : BaseController
{
    // ...
}

which will allow you to access custom fields in code like this:

User.Id
User.FirstName
User.LastName

But this will not work inside views. For that you would need to create a custom WebViewPage implementation:

public abstract class BaseViewPage : WebViewPage
{
    public virtual new CustomPrincipal User
    {
        get { return base.User as CustomPrincipal; }
    }
}

public abstract class BaseViewPage<TModel> : WebViewPage<TModel>
{
    public virtual new CustomPrincipal User
    {
        get { return base.User as CustomPrincipal; }
    }
}

Make it a default page type in Views/web.config:

<pages pageBaseType="Your.Namespace.BaseViewPage">
  <namespaces>
    <add namespace="System.Web.Mvc" />
    <add namespace="System.Web.Mvc.Ajax" />
    <add namespace="System.Web.Mvc.Html" />
    <add namespace="System.Web.Routing" />
  </namespaces>
</pages>

and in views, you can access it like this:

@User.FirstName
@User.LastName

Best Answer

Related Solutions

C# – How to create a dropdownlist from an enum in ASP.NET MVC

For MVC v5.1 use Html.EnumDropDownListFor

For MVC v5 use EnumHelper

For MVC 5 and lower

Asp.net-mvc – ASP.NET MVC – Set custom IIdentity or IPrincipal

Related Topic