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MVC SaveChanges Model with Nested List?

Posted on 2013-10-27
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938 Views
Last Modified: 2013-11-06
I have a model with a List and need to save changes. The VS 2012 debugger shows the Edit action model contains all indexed data. I'm used editor templates to achieve this.
The action method posted does not error and does not save the 'Limit' property changes. Help!

[Models]
    public class BudgetEdit
    {
        public List<BudgetList> BudgetList { get; set; }
    }

    public class BudgetList
    {
        public string Name { get; set; }
        public Nullable<int> ItemID { get; set; }
        public decimal Limit { get; set; }
        public System.DateTime Posted { get; set; }
    }


 [Action]
    public ActionResult Edit(Models.BudgetEdit model)
    {            
         var r = context.Budgets.Select(x => x.ItemID == model.BudgetList.FirstOrDefault().ItemID);

          if (r != null)
          {
              TryUpdateModel(r);
              context.SaveChanges();
          }
          return View((model);
     }
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Comment
Question by:WorknHardr
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9 Comments
 
LVL 96

Expert Comment

by:Bob Learned
ID: 39606841
What does the view look like?  Is this supposed to be a POST method, with [HttpPost] attribute?
0
 

Author Comment

by:WorknHardr
ID: 39607380
okay, here's the View and Editor Template complete code.

Note: I renamed the above posted model from 'BudgetEdit' to 'BudgetEditView ' because it's more intuitive.

I included a 'For' loop in the Action to step-through each List item, although I still don't have the mapping correct yet.

I've been exploring AutoMapper (unsuccessfully) like so:

[Action]
  public ActionResult Edit(BudgetEditView model)
  {
        for (int i = 0; i < model.BudgetList.Count; i++)
            {
                Budget b = context.Budgets.Find(model.BudgetList(i).ItemID);
                AutoMapper.Mapper.Map(model.BudgetList, b);
                context.SaveChanges();
            }
  }      

[View]
@model BudgetProjectUI.BudgetEditView

 @using (Html.BeginForm("Edit", "Budget", FormMethod.Post))
        {
            @Html.ValidationSummary(false)

            <fieldset>
                <legend>Month/Year </legend>
                <table>
                    <thead>
                        <tr>
                            <td><b>Category</b></td>
                            <td></td>
                            <td><b>Limit</b></td>
                        </tr>
                    </thead>
                    <tbody>

                        @Html.EditorFor(model => @Model.BudgetList)

                    </tbody>
                </table>
            </fieldset>  
                                               
            <input type="submit" value="Save Changes" />

[Editor Template]
@model BudgetProjectUI.BudgetList

<table>
    <tr>        
        <td>@Html.HiddenFor(model => model.BudgetID)</td>
        <td>@Html.HiddenFor(model => model.ItemID)</td>
        <td>@Html.HiddenFor(model => model.CategoryID)</td>
        <td style="width:150px">
            @Model.Name

        </td>
        <td></td>
        <td></td>
        <td>
            <div style="width:50px">
                @Html.EditorFor(model => model.Limit)

            </div>
        </td>
    </tr>
</table>
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LVL 96

Expert Comment

by:Bob Learned
ID: 39607580
You have a submit button, but I don't see that the action method has an HttpPost attribute.

Here is some "light reading" that should explain the need for HttpPost:

When to use [HttpGet] vs. [HttpPost] in ASP.NET MVC
http://www.linkedin.com/groups/When-use-HttpGet-vs-HttpPost-43315.S.261572227
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Author Comment

by:WorknHardr
ID: 39607646
Hmmm, interestingly enough the VS 2012 debugger shows the Edit action model contains all indexed data.
0
 
LVL 96

Expert Comment

by:Bob Learned
ID: 39608761
I overlooked this line, which does the same thing:

@using (Html.BeginForm("Edit", "Budget", FormMethod.Post))

If you are using Entity Framework, it is possible to determine what changes are detected.

public static void TestEntityState(BaseEntity entity)
{
   var state = _dataContext.ObjectStateManager.GetObjectStateEntry(entity);
   var propertyList = state.GetModifiedProperties();

   foreach (var property in propertyList)
   {
       Console.WriteLine("Property {0} changed from {1} to {2}", 
           property,
           state.CurrentValues[property],
          state.OriginalValues[property]);
   }
}

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0
 

Author Comment

by:WorknHardr
ID: 39617948
Okay, here's my latest failed attempt to save a collection back to its model. I receive the following error on 'var' below.

Q. So it must be pure Lambda to not error?

 "Error: LINQ to Entities does not recognize the method 'BudgetProjectUI.BudgetList get_Item(Int32)' method, and this method cannot be translated into a store expression."


  public ActionResult Edit(BudgetEditView model)
  {
         for (int i = 0; i < model.BudgetList.Count; i++)
         {
                var changes = (from b in context.Budgets where b.BudgetID == model.BudgetList(i).BudgetID select b.Limit).First();

                changes = model.BudgetList(i).Limit;
                context.SaveChanges();
          }
   }
0
 
LVL 96

Accepted Solution

by:
Bob Learned earned 500 total points
ID: 39625797
I showed you that code, so that you could double check the changes applied to Entity Framework.  That way, you could check to see if Limit was included in the changeset.
0
 

Author Comment

by:WorknHardr
ID: 39627258
Understood! I hope MVC 5 has a better way to do these things. Until then I'll use a reliable FormCollection.
0
 

Author Closing Comment

by:WorknHardr
ID: 39627266
Thx for helping...
0

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