C# , MVC and querying db help required.

[Deleted member 66701]

Hi All.

I've been learning C# and MVC over the weekend and I've hit a stumbling block. I want to query my DB and return a list of books. I've nearly got it working, i.e.:-

However, as you can see the Author isn't returned.

My DB is set up as follows:-

The DBVontroller.cs class is as follows:-

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using Book_Database.Models;

namespace Book_Database.Controllers
{
    public class DBController : Controller
    {

        BookDBEntities BookDB = new BookDBEntities();

        //
        // GET: /DB/Title
        public ActionResult Title(
            )
        {
            var books = BookDB.Books.ToList();
            return View(books);
        }
      }
}

My Model class is as follows:-

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace Book_Database.Models
{
    public class Book
    {
        public int      BookId      { get; set; }
        public int      GenreId     { get; set; }
        public int      AuthorId    { get; set; }
        public string   Title       { get; set; }
        public decimal  Price       { get; set; }
        public string   BookArtUrl  { get; set; }
        public int      Year        { get; set; }
        public Genre    Genre       { get; set; }
        public Author   Author      { get; set; }
    }
}

and the view code is:-

@model IEnumerable<Book_Database.Models.Book>

@{
    ViewBag.Title = "Browse";
}

<div class="col-sm-9 col-sm-offset-3 col-md-10 col-md-offset-2 main">
    <h1 class="page-header">Dashboard</h1>

    <div class="row placeholders">
        <div class="col-xs-6 col-sm-3 placeholder">
            <a href="Title"><img src="~/images/dashboard_blue.png" class="img-responsive" alt="Generic placeholder thumbnail"></a>
            <h4>@Model.Count()</h4>
            <span class="text-muted">Books</span>
        </div>
        <div class="col-xs-6 col-sm-3 placeholder">
            <a href="Author"><img src="~/images/dashboard_turquoise.png" class="img-responsive" alt="Generic placeholder thumbnail"></a>
            <h4>29</h4>
            <span class="text-muted">Authors</span>
        </div>
        <div class="col-xs-6 col-sm-3 placeholder">
            <a href="Genre"><img src="~/images/dashboard_blue.png" class="img-responsive" alt="Generic placeholder thumbnail"></a>
            <h4>16</h4>
            <span class="text-muted">Genres</span>
        </div>
        <div class="col-xs-6 col-sm-3 placeholder">
            <a href="#"><img src="~/images/dashboard_turquoise.png" class="img-responsive" alt="Generic placeholder thumbnail"></a>
            <h4>14</h4>
            <span class="text-muted">Publishers</span>
        </div>
    </div>

    <h2 class="sub-header">Results by Title</h2>
    <div class="table-responsive">
        <table class="table table-striped">
            <thead>
                <tr>
                    <th>#</th>
                    <th>Title</th>
                    <th>Author</th>
                    <th>Price</th>
                    <th>Year</th>
                    <th>Publisher</th>
                </tr>
            </thead>
            <tbody>
                @foreach (var book in Model)                
                {
                    <tr>
                        <td>@book.BookId</td>
                        <td>@Html.ActionLink(book.Title,"Details", new { id = book.BookId })</td>
                        <td>[B][U]WANT AUTHOR HERE[/U][/B]</td>
                        <td>@book.Price</td>
                        <td>@book.Year</td>
                        <td></td>
                    </tr>
                }

            </tbody>
        </table>
    </div>
</div>

So how to I return the author value that I "think" I have in my model?


As I said, I've only started a couple of days ago, so please be gentle

 

[Deleted member 66701]

so @book.Author.Name is blank?

I tried that but I get the following on runtime:-

 

[Deleted member 66701]

Try updating your Book class as below to link the Book class to the Author class:

public class Book
    {
        public int      BookId      { get; set; }
        public int      GenreId     { get; set; }
        public int      AuthorId    { get; set; }
        public string   Title       { get; set; }
        public decimal  Price       { get; set; }
        public string   BookArtUrl  { get; set; }
        public int      Year        { get; set; }
        public Genre    Genre       { get; set; }
        public virtual Author   Author      { get; set; }
    }

You absolute beauty! Works a treat.

So what's the significance of the "virtual" bit then?

 

[Deleted member 66701]

Have a read regarding lazy loading etc. https://msdn.microsoft.com/en-gb/data/jj574232.aspx

Thanks!

And I thought there was a lot to learn with PHP! I'm always so daunted by new stuff - so much to learn - seems like you'll never get to know everything about it!