Updated partial view model values in contoller after form submit

Question

In my sample MVC application I have a model

class SampleModel
{
    public int Id { get; set; }
    public string Name { get; set; }
    public List<Certification> Certifications { get; set; }
}

class Certification
{
    public int Id { get; set; }
    public string CertificationName { get; set; }
    public int DurationInMonths { get; set; }
}

My View (I need the certification details to be shown in a partial view)

@model SampleApplication.Model.SampleModel
<!-- other code... -->
@using (Html.BeginForm("SaveValues","Sample", FormMethod.Post, new { id= "saveForm" }))
{
    @Html.HiddenFor(m => m.Id, new { id = "hdnID" }) 
    @Html.TextBoxFor(m => m.Name, new { id = "txtName" })
    @{Html.RenderPartial("_CertDetails.cshtml", Model.Certifications);}
    <input type="submit" id="btnSubmit" name="btnSubmit" value="Update"  />
}

Partial View

@model List<SampleApplication.Model.Certification>
<!-- other code... -->
@if (@Model != null)
{
    for (int i = 0; i < @Model.Count; i++)
    {
        @Html.HiddenFor(m => m[i].Id , new { id = "CId" + i.ToString() })
        @Html.TextBoxFor(m => m[i].CertificationName,new{ id ="CName" + i.ToString() })
        @Html.TextBoxFor(m => m[i].DurationInMonths,new{ id ="CDur" + i.ToString() })
    }
}

Controller

[HttpPost]
public ActionResult SaveValues(SampleModel sm)
{
    //Here i am not getting the updated Certification details (in sm)
}

How I get the updated values of partial view in my controller after the form post? I am able to get the updated certification values when I am not using partialview. Is this the right way or should I follow some other methods?

Answer 1

Oh Nooo... It was my mistake :( . I gave Certification List as my partialview model

 @model List<SampleApplication.Model.Certification>

But I should use the same model(Main page model) in the partial view also.

 @model SampleApp.Models.SampleModel  

In the partial view the coding will be like

        @for (int i = 0; i < @Model.Certifications.Count; i++)
        {
            @Html.HiddenFor(m => m.Certifications[i].Id, new { id = "CId" + i.ToString() })
            @Html.TextBoxFor(m => m.Certifications[i].CertificationName, new { id = "CName" + i.ToString() })
            @Html.TextBoxFor(m => m.Certifications[i].DurationInMonths, new { id = "CDur" + i.ToString() })<br /><br />
        }

Now i am getting the updated values in my controller.

Thanks @Chris Pratt for the hint.

Answer 2

If sm.Certifications is coming back null, that means that either nothing was posted for that, or the modelbinder was unable to attach the posted data properly.

In your partial, you're defining the fields properly with an indexer, but initially, Certifications is a null list, so this code is never actually be run. That means, elsewhere you have some JavaScript logic that is adding new Certification fields to the page, dynamically, and my guess is that the field names that JavaScript is generating do not follow the indexing convention that the modelbinder expects. All your fields should be in the format of:

ListProperty[index].PropertyName

So in your case, your JS should be generating names like:

Certifications[0].CertificationName

In order for the data to be bound properly.