Asp.net MVC ModelState.Clear
- by Mr Grok
Can anyone give me a succinct definition of the role of ModelState in Asp.net MVC (or a link to one). In particular I need to know in what situations it is necessary or desirable to call ModelState.Clear().
Can anyone give me a succinct definition of the role of ModelState in Asp.net MVC (or a link to one). In particular I need to know in what situations it is necessary or desirable to call ModelState.Clear().
Bit open ended huh... sorry, I think it might help if tell you what I'm acutally doing:
I have an Action of Edit on a Controller called "Page". When I first see the form to change the Page's details everything loads up fine (binding to a "MyCmsPage" object). Then I click a button that generates a value for one of the MyCmsPage object's fields (MyCmsPage.SeoTitle). It generates fine and updates the object and I then return the action result with the newly modified page object and expect the relevant textbox (rendered using <%= Html.TextBox("seoTitle", page.SeoTitle)%) to be updated ... but alas it displays the value from the old model that was loaded.
I've worked around it by using ModelState.Clear() but I need to know why / how it has worked so I'm not just doing it blindly.
PageController:
[AcceptVerbs("POST")]
public ActionResult Edit(MyCmsPage page, string submitButton)
{
// add the seoTitle to the current page object
page.GenerateSeoTitle();
// why must I do this?
ModelState.Clear();
// return the modified page object
return View(page);
}
Aspx:
<%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<MyCmsPage>" %>
....
<div class="c">
<label for="seoTitle">
Seo Title</label>
<%= Html.TextBox("seoTitle", page.SeoTitle)%>
<input type="submit" value="Generate Seo Title" name="submitButton" />
</div>
