MVC CRUD By wizard without writing a single line in 2 minute - Step 4

CRUD functionality is the basic of learning of any language which we will see in this article and we will see how easy it is with asp.net MVC. We already seen, how we created the listing page without writing a single line of HTML. Same we will do for insert, update and delete by using the wizard. We will not write a single line of code but use the wizard to create controller action methods and views for use.

Delete CategoryController in Controller folder and Category folder in Views because we will create all the insert, update, delete and detail by just clicking some buttons by using wizard without writing a single line of code. I want to show the power and magic of ASP.Net MVC and Entity Framework. Let's create all these features

• Right click on the controller folder
• Click Add => Controller
• See the bellow image
• select MVC 5 Controller with views, using Entity Framework
• Click Add
• It will open a new dialog, see the second image
• Provide Model Class: Category
• Provide Data context class: LearningContext
• Don't check "Use async controller action", you can check it latter on
• Check "Generate views"
• Check "Reference script libraries"
• Check "Use a layout page": navigate to the view to /views/shared/_layout.cshtml, it is the master page
• Controller name: CategoriesController (automatically entered when you select the model), leave it as it is

• Click Add

  

  

  Take a deep breath, all the magic is done, time to enjoy it. Run the application and navigate to http://localhost:12345/categories and try to use all the features Create New, Edit, Detail and Delete, we will see every thing is working as it should be.

  Isn't it like a magic, have you written any line of code, no, but result is great. Much talked let's try to understand entire code generated by wizard part by part.

Open the CategoriesController file see the very first line inside the class

private LearningContext db = new LearningContext();

Created an object of our LearningContext class to access the data from database.

// GET: Categories
public ActionResult Index()
{
   return View(db.Categories.ToList());
}

First action method Index, is used to show the list of categories which we created manually in our previous article but this time it is created by th wizard. It return a view with parameter list of categories. Right click inside this action and click on Go To View, we will see the html

@model IEnumerable<Advance.Learning.WebApp.Models.Category>
@{
    ViewBag.Title = "Index";
    Layout = "~/Views/Shared/_Layout.cshtml";
}
<h2>Index</h2>
<p>@Html.ActionLink("Create New", "Create")</p>
<table class="table">
    <tr>
        <th>@Html.DisplayNameFor(model => model.CategoryName)</th>
        <th>@Html.DisplayNameFor(model => model.IsActive)</th>
        <th></th>
    </tr>
    @foreach (var item in Model) {
    <tr>
        <td>@Html.DisplayFor(modelItem => item.CategoryName)</td>
        <td>@Html.DisplayFor(modelItem => item.IsActive)</td>
        <td>
            @Html.ActionLink("Edit", "Edit", new { id=item.CategoryId }) |
            @Html.ActionLink("Details", "Details", new { id=item.CategoryId }) |
            @Html.ActionLink("Delete", "Delete", new { id=item.CategoryId })
        </td>
    </tr>
    }
</table>

One thing we need to note that there is no code for paging and it is true, it don't have any paging option. Html.ActionLink is only the code which is new for us. It renders the anchor tag of html.

   // Code
   @Html.ActionLink("Edit", "Edit", new { id=item.CategoryId })
   // Finale result after rendering will be
   <a href="/categories/Edit/1">Edit</a>

It have 10 overloaded version so we need to check them what is the best fit for us in different situations.

Detail action method

// GET: Categories/Details/5
public ActionResult Details(int? id)
{
  if (id == null){
    return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
  }
  Category category = db.Categories.Find(id);
  if (category == null){
    return HttpNotFound();
  }
  return View(category);
}

It's simply expecting a parameter, if not pass returns bad request or if record for provided id not found returns not found otherwise returns the view with detail of that category id. Here is the HTML of the Detail page:

@model Advance.Learning.WebApp.Models.Category
@{
    ViewBag.Title = "Details";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

<h2>Details</h2>
<div>
    <h4>Category</h4>
    <hr />
    <dl class="dl-horizontal">
      <dt>@Html.DisplayNameFor(model => model.CategoryName)</dt>
      <dd>@Html.DisplayFor(model => model.CategoryName)</dd>
      <dt>@Html.DisplayNameFor(model => model.IsActive)</dt>
      <dd>@Html.DisplayFor(model => model.IsActive)</dd>
    </dl>
</div>
<p>
    @Html.ActionLink("Edit", "Edit", new { id = Model.CategoryId }) |
    @Html.ActionLink("Back to List", "Index")
</p>

Create method:

• Get: used to render the blank page
• Post: used to post and save the data into database

• ValidateAntiForgeryToken attribute is used to prevent cross-site request forgery attacks.

  MVC's anti-forgery support writes a unique value to an HTTP-only cookie and then the same value is written to the form. When the page is submitted, an error is raised if the cookie value doesn't match the form value.

It's important to note that the feature prevents cross site request forgeries. That is, a form from another site that posts to your site in an attempt to submit hidden content using an authenticated user's credentials. The attack involves tricking the logged in user into submitting a form.

// GET: Categories/Created
public ActionResult Create()
{
    return View();
}

// POST: Categories/Create
// To protect from overposting attacks, please enable the specific properties you want to bind to, for 
// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create([Bind(Include = "CategoryId,CategoryName,IsActive")] Category category)
{
    if (ModelState.IsValid)
    {
        db.Categories.Add(category);
        db.SaveChanges();
        return RedirectToAction("Index");
    }

    return View(category);
}

The [Bind] attribute will let you specify a list of property names for which binding is allowed. Otherwise anyone can post some invalid values say IsDeleted=true and if he would be lucky to guess your model then it will save this value with IsDeleted true.

Is check ModelState.IsValid, if not then add all the errors and return back to the same page otherwise save the data into database and return back to the listing page.

Create page HTML:

@model Advance.Learning.WebApp.Models.Category
@{
    ViewBag.Title = "Create";
    Layout = "~/Views/Shared/_Layout.cshtml";
}
<h2>Create</h2>
@using (Html.BeginForm()) 
{
    @Html.AntiForgeryToken()    
    <div class="form-horizontal">
        <h4>Category</h4>
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })
        <div class="form-group">
            @Html.LabelFor(model => model.CategoryName, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.CategoryName, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.CategoryName, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.IsActive, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                <div class="checkbox">
                    @Html.EditorFor(model => model.IsActive)
                    @Html.ValidationMessageFor(model => model.IsActive, "", new { @class = "text-danger" })
                </div>
            </div>
        </div>

        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                <input type="submit" value="Create" class="btn btn-default" />
            </div>
        </div>
    </div>
}

<div>
    @Html.ActionLink("Back to List", "Index")
</div>

@section Scripts {
    @Scripts.Render("~/bundles/jqueryval")
}

• First line of the html is @model .... is the model which we need to render the page
• ViewBag.Title: is the page title to pass to layout page
• Layout: which layout (master) page this view will use
• @using (Html.BeginForm()): to render html form tag without any parameter for now
• @Html.AntiForgeryToken(): which we already discussed
• @Html.ValidationSummary: to show all the error as a list
• @Html.LabelFor: to render the label from the model
• @Html.EditorFor: to render the textbox from model, note how is added the class
• @section Scripts: to add the script at the bottom of the layout page

Edit an existing record:

It need two action method one HttpGet to get the data by category Id and render the view with complete detail and other HttpPost to save the data back to database, it is very similar to our previous create action, see this

// GET: Categories/Edit/5
public ActionResult Edit(int? id)
{
    if (id == null)
    {
        return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
    }
    Category category = db.Categories.Find(id);
    if (category == null)
    {
        return HttpNotFound();
    }
    return View(category);
}

// POST: Categories/Edit/5
// To protect from overposting attacks, please enable the specific properties you want to bind to, for 
// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Edit([Bind(Include = "CategoryId,CategoryName,IsActive")] Category category)
{
    if (ModelState.IsValid)
    {
        db.Entry(category).State = EntityState.Modified;
        db.SaveChanges();
        return RedirectToAction("Index");
    }
    return View(category);
} 

Do see any new code which need to explain, I don't think so. Even if there is any, just egnore it for now because our next page we will create manually and will explain every line of code.

Delete a record:

Delete action method (Delete) is same as our other action methods but if you will note the DeleteConfirmed, it have some extra attributes. Why we need two different name for delete, if you can see closely both Delete and DeleteConfirmed both have only one parameter and a class cannot have two methods with same number and type of parameters, that's why it created a different name for two methods but to post will try to past the data to Detelet so it added [HttpPost, ActionName("Delete")] as attribute.

// GET: Categories/Delete/5
public ActionResult Delete(int? id)
{
    if (id == null)
    {
        return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
    }
    Category category = db.Categories.Find(id);
    if (category == null)
    {
        return HttpNotFound();
    }
    return View(category);
}

// POST: Categories/Delete/5
[HttpPost, ActionName("Delete")]
[ValidateAntiForgeryToken]
public ActionResult DeleteConfirmed(int id)
{
    Category category = db.Categories.Find(id);
    db.Categories.Remove(category);
    db.SaveChanges();
    return RedirectToAction("Index");
}

Delete page html:

@model Advance.Learning.WebApp.Models.Category

@{
    ViewBag.Title = "Delete";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

<h2>Delete</h2>

<h3>Are you sure you want to delete this?</h3>
<div>
    <h4>Category</h4>
    <hr />
    <dl class="dl-horizontal">
        <dt>
            @Html.DisplayNameFor(model => model.CategoryName)
        </dt>

        <dd>
            @Html.DisplayFor(model => model.CategoryName)
        </dd>

        <dt>
            @Html.DisplayNameFor(model => model.IsActive)
        </dt>

        <dd>
            @Html.DisplayFor(model => model.IsActive)
        </dd>

    </dl>

    @using (Html.BeginForm()) {
        @Html.AntiForgeryToken()

        <div class="form-actions no-color">
            <input type="submit" value="Delete" class="btn btn-default" /> |
            @Html.ActionLink("Back to List", "Index")
        </div>
    }
</div>

That's it for now. We will try the same feature for products listing, create, edit, detail and delete and will create all the page by adding code line by line to understand every part of the code in detail.

Questions and suggestions are always welcome.

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