Use javascript variable in razor: "name 'I' does not exist in the current context"

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I have a table of one column of an attribute List<string> strengthC

C#

<table>
<thead>
 <tr>
  <th>
     @Html.LabelFor(model => model.strengthC, htmlAttributes: new { @class = "control-label col-md-3" })
  </th>
 </tr>
</thead>
<tbody>
 <tr>
  <td>
     @Html.EditorFor(model => model.strengthC[0], new { htmlAttributes = new { @class = "form-control", @style = "background-color: Azure; opacity:0.9" } })
@Html.ValidationMessageFor(model => model.strengthC, "", new { @class = "text-danger" })
  </td>
 </tr>
</tbody>
</table>

I want to add new rows to the table with a counter 'i' that is the index of strength[i] using Javascript.

What I have tried:

C#

<script type="text/javascript">
var i = 0;
function newRow() {
   i += 1;
$('#mainTable tr:last').after('<tr><td>@Html.EditorFor(model => model.strengthC[i], new { htmlAttributes = new { @class = "form-control", @style = "background-color: Azure; opacity:0.9" } })
@Html.ValidationMessageFor(model => model.strengthC, "", new { @class = "text-danger" }</td></tr>');
    }
</script>

The problem here is that model.strengthC[i] doesn't accept 'i' as a parameter: "name 'i' does not exist in the current context"

Posted 16-Mar-18 3:58am

TempoClick

Updated 16-Mar-18 4:26am

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Comments

F-ES Sitecore 16-Mar-18 10:08am

You can't do that because your razor code runs on the server to generate html, which is then send to the browser to execute. Your model.strength[i] line is being executed on the server before the resulting js is sent to the browser to be executed, so "i" as a javascript concept doesn't yet exist, it is looking for a variable called "i" in your server-code.

You're going to have to create the html to add a new row normally. If you look at the source of your page you'll see how you need to construct the elements, it'll probably be an input with a name like "strength[0]", "strength[1]" etc, so you just need to create a new input with a name that is "strength[n]" where "n" is the next number in the sequence.

If you google "mvc create dynamic editor via javascript" you'll probably find sample code.

TempoClick 16-Mar-18 11:20am

But how to pass n to the javascript function and then use it in strengthC[]?

1 solution

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#realJSOP · Answer 1 · 2018-03-16T04:27:00

Solution 1

First, why are you worried about the index of the item you're editing? Seems weird given the nature of EditFor.

Don't do it on the client side. Do it this way:

HTML

@foreach(var item in Model)
{
    @* if you really need the index, you can do this in a foreach loop *@
    int index = Model.IndexOf(item);
    <tr>
        <td>
            @Html.EditFor(m=>m.strengthC[index],...)
            ...
        </td>
   </tr>
}

Posted 16-Mar-18 4:27am

#realJSOP

Comments

TempoClick 16-Mar-18 11:18am

I am inserting a new row with a button click. then I need to pass all the items inserted (strengthC[0], strengthC[1].....) to controller.

#realJSOP 16-Mar-18 13:42pm

You should still do that on the server side. MVC supports it.