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Saturday, March 16, 2013

Html.Partial,Html.RenderPartial,Html.Action and Html.RenderAction in ASP.NET MVC

Html.Partial and Html.RenderPartial
        The Html.Partial helpers renders a partial view in to string.Typically, a partial view contains reusable markup you want to render from inside multiple different views. Partial has four overloads

public void Partial(string partialViewName);
public void Partial(string partialViewName, object model);
public void Partial(string partialViewName, ViewDataDictionary viewData);
public void Partial(string partialViewName, object model,
ViewDataDictionary viewData);
Example : 

The RenderPartial  is similar to Partial, but RenderPartial writes directly to the response
output stream instead of returning a string. For this reason, you must place RenderPartial inside
a code block instead of a code expression
Example : 
So, which should you use, Partial or RenderPartial
            In general, you should prefer Partial to RenderPartial because Partial is more convenient (you don’t have to wrap the call in a code block with curly braces). However, RenderPartial may result in better performance because it writes directly to the response stream.
Html.Action and Html.RenderAction
         Html.Action and Html.RenderAction are similar to Partial and RenderPartial.Action  executes a separate controller action and display the results.the only difference between Action and RenderAction is that RenderAction writes directly to the response.

Example :
      Imagine you are using the following controller

public class ActionDemoController : Controller {
public ActionResult Index() {
return View();
public ActionResult DisplayMenu() {
var menu = GetMenuFromSomewhere();
return PartialView(menu);

The Menu action builds a menu model and returns a partial view with just the menu:
@model Menu
@foreach (var item in Model.MenuItem) {
In your Index.cshtml view, you can now call into the Menu action to display the menu:
<head><title>Index with Menu</title></head>

<h1>Welcome to the Index View</h1>

       Notice that the Menu action is marked with a ChildActionOnlyAttribute. The attribute prevents the runtime from invoking the action directly via a URL. Instead, only a call to Action or RenderAction can invoke a child action. The ChildActionOnlyAttribute isn’t required, but is generally recommended for child actions.

Passing values to Action
       Sometimes you want to pass parameters in to the action.


public ActionResult Menu(MenuParameters param) {
return PartialView(

@Html.Action("Menu", new {
options = new 

{ Width=400, Height=500 } })

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