Do something on Page Load in ASP.NET MVC

Question

I have a dropdown on my homepage that I need to bind to a data source when the page loads. I have a basic controller for the page:

public class HomeController : Controller
{
    public ActionResult Index()
    {
        return View();
    }
}

I'd like to do something like this on the view page:

<select id="ddlCities">
    <% foreach (var item in ViewData.Model.Cities) { %>
        <option value='<%= item.CityID %>'><%= item.CityName %></option>
    <% } %>
</select>

So do I need to modify my Index() function to return a View Model? I'm coming from Web Forms and a little confused about how this works.

jim tollan · Accepted Answer · 2010-09-30 19:58:17Z

3

Steven,

You can do it even simpler than that. Just use the html helper:

<%=Html.DropDownList("ddlCities", ViewData["Cities"])%>

this 'should' work for you, as long as your model has an ienumerable list called Cities.

of course, your 'best' course of action would be to have a strongly typed model that was passed to your view, such as:

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<SubSonic.Web.Models.Country>" %>

(in your Model, Country would have a collection of Cities - you get the drift :))

but the above would still work.

edited Sep 30, 2010 at 19:58

answered Sep 30, 2010 at 19:52

jim tollan

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1 Comment

Steven Over a year ago

I think this is the best solution for what I'm trying to do here. Thanks.

Henrik P. Hessel · Accepted Answer · 2010-09-30 19:50:36Z

3

You should take a look into Action Filters.

You can overwrite methods of the ActionFilterAttribute class for different states of an "action" life cycle.

OnActionExecuting – This method is called before a controller action is executed.
OnActionExecuted – This method is called after a controller action is executed.
OnResultExecuting – This method is called before a controller action result is executed.
OnResultExecuted – This method is called after a controller action result is executed.

edited Sep 30, 2010 at 19:50

answered Sep 30, 2010 at 19:36

Henrik P. Hessel

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3 Comments

Buildstarted Over a year ago

Be careful though because OnActionExecuted isn't always called.

Henrik P. Hessel Over a year ago

Yeah, maybe my solution is a bit too much for his problem. But always good know about the existence of these methods.

Steven Over a year ago

I agree with Henrik, this may be a tad complicated for what I'm trying to do. Thanks for the answer though, I didn't know about Action Filters.

Rony · Accepted Answer · 2010-09-30 19:53:09Z

2

public class HomeController : Controller
{
    public ActionResult Index()
    {
        var cities = <data access code>

        return View(cities);
    }
}

@ Page Title='' Language='C#' MasterPageFile='~/Views/Shared/Site.Master' Inherits=System.Web.Mvc.ViewPage<IEnumerable<City>> 

<select id="ddlCities">
    <% foreach (var item in ViewData.Model.Cities) { %>
        <option value='<%= item.CityID %>'><%= item.CityName %></option>
    <% } %>
</select>

answered Sep 30, 2010 at 19:53

Rony

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2 Comments

Steven Over a year ago

That would work if I only had to bind that dropdown, but I have several other dropdowns that I need to bind to data sources when the page loads. Sorry, should've been more specific.

Rony Over a year ago

you can either make your model more complex to hold those collections or pass the collection to the view within a ViewData dictionary like this ViewData["cities"] = ... ViewData["countries"] =... and in the view you can cast it back foreach (var item in(IEnumerable<City>) ViewData["cities"])

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