Getting index value on razor foreach

问题:

I'm iterating a List<T> in a razor foreach loop in my view which renders a partial. In the partial I'm rendering a single record for which I want to have 4 in a row in my view. I have a css class for the two end columns so need to determine in the partial whether the call is the 1st or the 4th record. What is the best way of identifying this in my partial to output the correct code?

This is my main page which contains the loop:

@foreach (var myItem in Model.Members){

        //if i = 1
        <div class="grid_20">
        <!-- Start Row -->

        //is there someway to get in for i = 1 to 4 and pass to partial?
        @Html.Partial("nameOfPartial", Model)

        //if i = 4 then output below and reset i to 1
        <div class="clear"></div>
        <!-- End Row -->
        </div>

}

I figure I can create a int that I can update on each pass and render the text no problem here but it's passing the integer value into my partial I'm more concerned about. Unless there's a better way.

Here is my partial:

@{
switch()
case 1:
        <text>
        <div class="grid_4 alpha">
        </text>
break;
case 4:
        <text>
        <div class="grid_4 omega">
        </text>
break;
default:
        <text>
        <div class="grid_4">
        </text>
break;
}

        <img src="Content/960-grid/spacer.gif" style="width:130px; height:160px; background-color:#fff; border:10px solid #d3d3d3;" />
        <p><a href="member-card.html">@Model.Name</a><br/>
        @Model.Job<br/>
        @Model.Location</p>
</div>

Not sure if I'm having a blonde day today and this is frightfully easy but I just can't think of the best way to pass the int value in. Hope someone can help.

回答1:

 @{int i = 0;}
 @foreach(var myItem in Model.Members)
 {
     <span>@i</span>
     i++;
 }

回答2:

//this gets you both the item (myItem.value) and its index (myItem.i)
@foreach (var myItem in Model.Members.Select((value,i) => new {i, value}))
{
    <li>The index is @myItem.i and a value is @myItem.value.Name</li>
}

More info on my blog post http://jimfrenette.com/2012/11/razor-foreach-loop-with-index/

回答3:

Or you could simply do this:

@foreach(var myItem in Model.Members)
{    
    <span>@Model.Members.IndexOf(myItem)</span>
}

回答4:

Take a look at this solution using Linq. His example is similar in that he needed different markup for every 3rd item.

foreach( var myItem in Model.Members.Select(x,i) => new {Member = x, Index = i){
    ...
}

回答5:

Is there a reason you're not using CSS selectors to style the first and last elements instead of trying to attach a custom class to them? Instead of styling based on alpha or omega, use first-child and last-child.

http://www.quirksmode.org/css/firstchild.html

回答6:

IndexOf seems to be useful here.

@foreach (myItemClass ts in Model.ItemList.Where(x => x.Type == "something"))
    {
       int currentIndex = Model.ItemList.IndexOf(ts);
       @Html.HiddenFor(x=>Model.ItemList[currentIndex].Type)

...

回答7:

Very Simple:

     @{
         int i = 0;
         foreach (var item in Model)
         {
          <tr>
          <td>@(i = i + 1)</td>`
          </tr>
         }
      }`

回答8:

All of the above answers require logic in the view. Views should be dumb and contain as little logic as possible. Why not create properties in your view model that correspond to position in the list eg:

public int Position {get; set}

In your view model builder you set the position 1 through 4.

BUT .. there is even a cleaner way. Why not make the CSS class a property of your view model? So instead of the switch statement in your partial, you would just do this:

<div class="@Model.GridCSS">

Move the switch statement to your view model builder and populate the CSS class there.

回答9:

In case you want to count the references from your model( ie: Client has Address as reference so you wanna count how many address would exists for a client) in a foreach loop at your view such as:

 @foreach (var item in Model)
                        {
                            <tr>
                                <td>
                                    @Html.DisplayFor(modelItem => item.DtCadastro)
                                </td>

                                <td style="width:50%">
                                    @Html.DisplayFor(modelItem => item.DsLembrete)
                                </td>
                                <td>
                                    @Html.DisplayFor(modelItem => item.DtLembrete)
                                </td>
                                <td>
                                    @{ 
                                        var contador = item.LembreteEnvolvido.Where(w => w.IdLembrete == item.IdLembrete).Count();
                                    }
                                    <button class="btn-link associado" data-id="@item.IdLembrete" data-path="/LembreteEnvolvido/Index/@item.IdLembrete"><i class="fas fa-search"></i> @contador</button>
                                    <button class="btn-link associar" data-id="@item.IdLembrete" data-path="/LembreteEnvolvido/Create/@item.IdLembrete"><i class="fas fa-plus"></i></button>
                                </td>
                                <td class="text-right">
                                    <button class="btn-link delete" data-id="@item.IdLembrete" data-path="/Lembretes/Delete/@item.IdLembrete">Excluir</button>
                                </td>
                            </tr>
                        }

do as coded:

@{ var contador = item.LembreteEnvolvido.Where(w => w.IdLembrete == item.IdLembrete).Count();}

and use it like this:

<button class="btn-link associado" data-id="@item.IdLembrete" data-path="/LembreteEnvolvido/Index/@item.IdLembrete"><i class="fas fa-search"></i> @contador</button>

ps: don't forget to add INCLUDE to that reference at you DbContext inside, for example, your Index action controller, in case this is an IEnumerable model.