Understanding how DropDownListFor is working in MVC3

Question

I\'m new to MVC3 and have been working on a small site using EF and \'Code First\'. I\'m trying to do a few things in a view dealing with a drop down list and am wondering w

Answer 1

I want a user to be able to select a rule from the dropdownlist, and depending upon which rule was selected, I would like a label on the page to show the rule name (without posting)

You will need javascript here. jQuery would be perfect for the job. I would start by providing a deterministic id for the dropdown because if you run this view inside a template there could be prefixes added to the id which would ruin our javascript id selectors (see below):

@Html.DropDownListFor(
    x => x.D1K2N3CARules,
    new SelectList(Model.D1K2N3CARules, "ID", "Rule"),
    new { id = "ruleDdl" }
)

then provide some container which will receive the selected value:

<div id="ruleValue" />

and finally in a separate javascript file subscribe for the change event of the dropdown list and update the container with the selected value/text:

$(function() {
    // subscribe for the change event of the dropdown
    $('#ruleDdl').change(function() {
        // get the selected text from the dropdown
        var selectedText = $(this).find('option:selected').text();

        // if you wanted the selected value you could:
        // var selectedValue = $(this).val();

        // show the value inside the container
        $('#ruleValue').html(selectedText);
    });
});

I also need to be able to send the selected rule onto the next page.

You could put your dropdown inside a form

@using (Html.BeginForm("NextPage", "Foo"))
{
    @Html.DropDownListFor(
        x => x.D1K2N3CARules,
        new SelectList(Model.D1K2N3CARules, "ID","Rule")
    )    
    <input type="submit" value="Go to the next page" />
}

and the NextPage controller action will receive the selected value.