CODEWITHSUNDEEP
asp.netasp.net-mvc-2asp.net-ajax
Evan Davis
Evan Davis

Reputation: 36612

Dynamically add items to a collection in MVC2 using EditorFor()

I'm trying to do this: Editing a variable length list, ASP.NET MVC 2-style

In the post he mentions that it could be done with less code using Html.EditorFor(), but that it would be more difficult because of the indexes. Well, that's exactly what I want to do, and I don't know where to begin.

I'm an ASP.NET novice who just completed the Nerd Dinner tutorial before jumping into a project at work, so any help would be appreciated.

Update 1: Instead of generating a GUID for each item in the collection, I'd like to generate incremental indexes starting with 0. Right now the field names look like "gifts[GUID].value"; I would like them to be "gifts[0].value","gifts1.value" etc. but I don't understand how the collection keeps track and generates these indices.

Upvotes: 2

Views: 812

Answers (2)

sonyisda1
sonyisda1

Reputation: 434

In response to your update about generating indexes instead of GUIDs, the original linked article had a few comments from others that tried to solve the same issue but none of them worked for me. What I found was the collection with index was referenced in the following location:

html.ViewContext.ViewData.TemplateInfo.HtmlFieldPrefix

So I wrote a helper function to parse out the index (and if there is a problem then the GUID would be generated)

public static string GetCollectionItemIndex(this HtmlHelper html, string collectionName)
     {
     int idx;
     string sIdx;

     if (Int32.TryParse(Regex.Match(html.ViewContext.ViewData.TemplateInfo.HtmlFieldPrefix, @"\d+").Value, out idx))
        {
        sIdx = idx.ToString();
        }
     else
        {
        sIdx = Guid.NewGuid().ToString();
        }

     return sIdx;
     }

I edited the BeginCollectionItem(..) function to call this helper function when setting the item index:

     string itemIndex = idsToReuse.Count > 0 ? idsToReuse.Dequeue() : GetCollectionItemIndex(html, collectionName);

Hope this helps someone else!

Upvotes: 1

Darin Dimitrov
Darin Dimitrov

Reputation: 1039498

Well, you begin by defining an editor template (~/Views/Shared/EditorTemplates/Gift.ascx):

<%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<MyApp.Models.Gift>" %>
<div class="editorRow">
    <% using(Html.BeginCollectionItem("gifts")) { %>
        Item: <%= Html.TextBoxFor(x => x.Name) %> 
        Value: $<%= Html.TextBoxFor(x => x.Price, new { size = 4 }) %> 
    <% } %>
</div>

And then replace the RenderPartial call with EditorForModel:

<% using(Html.BeginForm()) { %>
    <div id="editorRows">
        <%= Html.EditorForModel() %>
    </div>
    <input type="submit" value="Finished" />
<% } %>

Once you've tried this you may come back and ask if you have any problems by explaining the symptoms.

Upvotes: 0

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