I have some related entities in my EF model, as show below in the form of “Reader” and “Category”, and the relationship between them, i.e. many to many.

When it came to proucing a view and action to perofrm the Create Reader action, I was somewhat puzzled as to how I could allow the user to select one or more categories for a reader. 

I started by having a view model that contained a list of all possible categories and then looping around these in my view and writing a check box out for each one.  When the form was submitted I looked through the form collection to find if any of the category check boxes had been selected.  I didn’t like this one bit and so I set out to find a cleaner way of carrying it out.

After some (quite a lot actually) searching, I stumbled accross the MultiSelectList type, which I could use in my ViewModel and then allow the default model binding to step in and do the leg work for me Great!

So, I created a view model, a simplified version of which you can see below;

    public class ReaderCreateViewModel : CustomViewModelBase
    {

        public ReaderCreateViewModel()
        {
            ReaderDetails = new Reader();
            CategoriesList = GetCategories(null);
        }

        public Reader ReaderDetails { get; set; }
        public MultiSelectList CategoriesList { get; private set; }
        public int[] SelectedCategories { get; set; }

        public MultiSelectList GetCategories(int[] selectedValues)
        {
            var te = new myEntities();
            List<Category> categories = te.Categories.ToList();
            return new MultiSelectList(categories, “id”, “Name”, selectedValues);
        }
    }

 As you can see from the code above, the view model contains my Reader entity, a list of type MultiSelectList, which is a list of available categories and an array of integers which represent the Id of any selected Categories.

Then to add a listbox to my view that will bind the MultiSelectList, I simply insert the following into my view.

            <p>
             <label for=”SelectedCategories”>Categories:</label>
        <%= Html.ListBox(“SelectedCategories”, Model.CategoriesList) %>
            </p>

Finally in my controller, I can simply check the SelectedItems object in my model for any selected Ids and add them to the Reader Categories list like this;

            if (model.SelectedCategories != null)
            {
                foreach (var selectedCat in model.SelectedCategories)
                {
                    int selectedCatId = selectedCat;
                    Category category = DataContext.Categories.Where(c => c.id                  == selectedCatId).FirstOrDefault();
                    reader.Categories.Add(category);
                }
            }

And that’s it.  Now there is probably a much better way of doing all or some of the above, but this worked perfectly for me when I needed it, so I hope it helps someone else out as well.  The final multi-select list box looked something like this;

Technorati Tags: ASP.NET MVC, Entity Framework, MVC

When I first started using MVC, I simply passed the ViewData required for the MasterPage along with every action, but even with a small site, this was a lot of code replication.

To solve this problem, we can create an ApplicationController class which inherits from the Controller class we all know and love.  Your applications’ controllers then in turn simply inherit from this new ApplicationController.

Below is a simple example of an ApplicationController.

namespace MvcSite.Controllers
{
    public abstract class ApplicationController : Controller
    {
        private MyEntities _dataContext = new MyEntities();

        public MyEntities DataContext
        {
            get { return _dataContext; }
        }

        public ApplicationController()
        {
            ViewData["categories"] = DataContext.Categories.ToList();
        }

    }
}

Hope this helps someone else as well. Certainly removed a headache for me!

Technorati Tags: ASP.NET MVC

Beta 2 brings many improvements to the table, including improvements in Sharepoint, WPF, ASP.NET, WinForms, as well as improvements to the core IDE and testing tools. I saw some of these IDE improvements at an event with Scott Gu in Manchester a couple of weeks ago and they look pretty cool.

Visual Studio now comes in several flavours, namely Premium, Professional and Ultimate and the good news is that TFS 2010 comes out of the box with all three.  Apparently it only takes 20 minutes to setup source control, bug and issue tracking and automated build with it.

Finally, another great piece of news is that this release also ships with a Go-live license, so this can be used for production projects if you wish

If you are a member of MSDN and want to download the beta now, you can get it from here.

For more information on the release visit Scott Gu’s blog where you he has started a series of posts on the new features in 2010 Beta 2.

Have any of you been using Beta 1? Will you be using Beta 2? What do you think of the way 2010 and .Net 4.0 are shaping up?

Technorati Tags: .NET 4.0, beta 2, visual studio 2010, vs2010

Scott Guthrie, Microsoft’s Corporate Vice Presedent and all round .Net Guru is coming to Manchester, UK, later this month to talk about what’s new with Visual Studio 2010, ASP.Net 4.0, Silverlight 3 and upcoming improvements to the MVC Framework!

Seating for this event, entitled Guathon 2009,  is very limited and as such you can only join the wait list at the moment, but I have been lucky enough to secure a place at what promises to be a fantastic workshop.

The announcement on the event home page over at DeveloperDeveloperDeveloper also has a funny section of “things you might not know about Scott Gu”, such as;

When Scott Guthrie throws exceptions, it’s across the room.

All arrays Scott Guthrie declares are of infinite size, because Scott Guthrie knows no bounds.

Scott Guthrie doesn’t have disk latency because the hard drive knows to hurry the hell up.

Scott Guthrie writes code that optimizes itself.

Scott Guthrie can’t test for equality because he has no equal.

Scott Guthrie doesn’t need garbage collection because he doesn’t call .Dispose(), he calls .DropKick().

For the rest of this amusing list and more info on the event or to add yourself to the wait list, visit the event home page.

Technorati Tags: ASP.Net, ASP.NET MVC, scott gu, scott guthrie, silverlight 3, visual studio 2010

Title:

Publisher: Wrox

Authors: Nick Beradi, Al Katawazi, Marco Bellinaso

It seems that recently every man and his dog have been talking about ASP.Net MVC and the many advantages it brings along with it.  I have to admit that, up until now, I have not really looked into it a great deal, except for watching a couple of sessions at last years MSDN Roadshow.  Anyway, I decided that it was about time I found out more about ASP.Net MVC and see if it really was worth all of the hype.

Why did I read THIS book?

The reason I chose this book was two fold – firstly, it claimed to give you a good grounding in using ASP.Net MVC to those with experience of ASP.Net Web Development.  Secondly, in the books’ own words it provided “solid, workable solutions to real work problems” (I was dubious about this claim….many books I have read have claimed to do this and failed miserably with the first couple of chapters).

First Impressions

Right from the very first chapter it starts off on the correct foot, giving an overview of the application you will create as you work through the book, that application being The Beer House, which is available for download as a starter kit.  The main attraction of this application to me was that it contained many of the features I often implement in my own applications, such as forums, article management and user profile / membership management.  The idea of reading a book that directly relates to my real-world programming was a big pull for me.

Thankfully, this book certainly does not try and force MVC down your throat as a must-use solution, instead giving an honest opinion that, yes MVC is very useful in many situations, but that in other situations, classic ASP.Net Web Forms may still be the more logical option.  This is a refreshing change from some of the other more self-righteous books I have had the des-pleasure of sampling where they simply see their subject matter and related methods as the only way to go.

What’s Covered?

I don’t think I can put the content of the book in better words that the book itself, so here are those very words;

All of the above is covered in ample detail and I really did find this book extremely useful when relating the MVC implementation with my tradition Web Forms methods.

I especially liked the fact that attention was paid to the design of the application you create.  Coming from a web design background I am often astounded by the lack of attention paid to this area and it was pleasing to see a chapter dedicated to this for the non-design minded developer.

The other thing I loved about this book was that as well as ensuring every detail was covered off when developing each solution for the Beer House application, the authors have made a clear effort to highlight when something more may be needed in different circumstances and provided sample code and examples where needed.

Source Code Problems

Probably the only bad thing I have to say about this book were the problems I had when attempting to get the source code to compile once I had downloaded it from the Wrox web site.  I think the main problem was that the code on the site was possibly an old version with several other versions kicking around the internet.  I am unsure as to which was the correct up-to-date copy.

However, all that said, with some tinkering, I did manage to get it to compile and what a lovely application it is.

The Final Verdict

I found this book to be an extremely concise and focused journey through ASP.Net MVC and a perfect introduction to the subject and I would highly recommend it to anybody who is looking for a good grounding in the subject.

This was also my first read of a book from the Problem – Design – Solution series from Wrox, and if the other books in the series are in a similar style, then I look forward to reading more as the straight forward style with real-world connections suited me down to the ground.  

You can find this book for sale on Amazon or from the Wiley web site.

Technorati Tags: ASP.Net, ASP.NET MVC, book review, C#, wrox