asp.net mvc and model binding objects with sub objects

Question

I'm trying to get model bind a sub class in a form.

I have a Page class with a related PageContent class. There are many PageContent objects in a Page object. ie Page.PageContents

I return Page as the Model and I can see all the PageContent items.

However I'm a bit blurry on how to assign the PageContent items to the form so it'll keep it's model binding.

When I Post the Page model back into the controller, the PageContent list is empty.

Here is a snippet of the form:

<% using (Html.BeginForm("SavePage", "Admin")) {%>

    <fieldset>
        <legend>Fields</legend>
        <%=Html.Hidden("PageId", Model.PageId) %>
        <p>
            <label for="Title">Title:</label>
            <%= Html.TextBox("Title", Model.Title) %>
            <%= Html.ValidationMessage("Title", "*") %>
        </p>
        <p>
            <label for="SysName">SysName:</label>
            <%= Html.TextBox("SysName", Model.SysName) %>
            <%= Html.ValidationMessage("SysName", "*") %>
        </p>

        <% 
            int i = 0;
       foreach (var pageContent in Model.PageContents)

           { %>
            <div>
                <%=Html.Hidden("PageContents[" + i + "].PageContentId", pageContent.PageContentId) %>
                <%=Html.TextArea("PageContents[" + i + "].Content", pageContent.Content)%>                
            </div>
        <%
            i++;
       } %>

        <p>
            <input type="submit" value="Save" />
        </p>
    </fieldset>

<% } %>

I'm thinking I haven't made the PageContents aspect of the form correctly.

EDIT: Here is the basic controller method I POST to:

public ActionResult SavePage(Page page)
    {
        // do stuff with page.PageContents
        return View("PageEdit", page);
    }

I'm not using the Request.Form style

Please help :D

What is the type of Page.PageContents ? Is it an IList<PageContent> or an PageContent[] ? I never was able to bind to an array. — BMBM
– BMBM, Commented Nov 27, 2009 at 11:29
i'm using the direct DBML automagic clases. So its an EntitySet<>: EntitySet<PageContent> Page.PageContents — sf.
– sf., Commented Nov 27, 2009 at 11:33

Community · Accepted Answer · 2017-05-23 12:07:10Z

1

You said Page.PageContents is an EntitySet<PageContent> and that you are using auto-generated classes. So, I guess, you are using LINQ to SQL? If so, then you can use partial classes in order to add properties to the generated class

I remember that I had a similiar problem, I wasnt able to bind to EntitySet<T> properties. I think I fixed it by using a proxy / placeholder property which was an IList<T> what effectively set the actual property. So, in your case, that would look something like this:

// Your partial class, adding a property to the generated class
public partial class Page
{
    // Bind to this property
    public IList<PageContent> MyPageContents
    {
        set 
        { 
            var set = new EntitySet<PageContent>();
            set.AddRange(value);
            PageContents = set; 
        }
        get  { return PageContents; }
    }
}

// This and probably a lot more is created by LINQ to SQL
public partial class Page {
    // ...

    public EntitySet<PageContent> PageContents
    {
        get;
        set;
    }

    // ...
}

I think partial classes have to be in the same namespace as the auto generated class. More info here: Adding new methods to LINQ to SQL generated classes

And then, in your form, you bind to MyPageContents (you can use a better name of course) instead of PageContents.

Hopefully it works for you, it is quite some time ago since I last used LINQ to SQL.

edited May 23, 2017 at 12:07

CommunityBot

11 silver badge

answered Nov 27, 2009 at 11:45

BMBM

16.1k19 gold badges83 silver badges135 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

sf. Over a year ago

bam, it works :D cheers you are a star. Hopefully this little trick is fixed in mvc 2.0

Collectives™ on Stack Overflow

asp.net mvc and model binding objects with sub objects

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related