Asp.Net Mvc Strongly Typed Views Complete Guide

Top 10 Questions and Answers on ASP.NET MVC Strongly Typed Views

1. What is a Strongly Typed View in ASP.NET MVC?

Example:

@model MyNamespace.MyModel
@Html.LabelFor(m => m.PropertyName)
@Html.EditorFor(m => m.PropertyName)

2. How do you create a Strongly Typed View in ASP.NET MVC?

Answer: Creating a strongly typed view in ASP.NET MVC is straightforward. You can do this either through scaffolding or manually.

Using Scaffolding:

• In Visual Studio, right-click on the "Views" folder.
• Select "Add" -> "View..."
• Enter a name for your view.
• In the "Model class" dropdown, choose the model you want to bind to.
• Select a template, and click "Add."

Creating Manually:

1. Create a new view.
2. Specify the model type at the top of the .cshtml file using the @model directive.
3. Create UI elements and bind them to model properties using HTML helpers.

Example:

@model MyNamespace.MyModel
<h2>@Model.PropertyName</h2>

3. Why should you use Strongly Typed Views?

Answer:

1. Type Safety: Strongly typed views help you catch errors at compile time, reducing runtime errors due to null references or incorrect data types.
2. IntelliSense Support: You can use IntelliSense to list properties and methods of your model, improving coding efficiency.
3. Clean and Maintainable Code: They make your code cleaner and more maintainable by ensuring that the view is aware of the data it needs to display.
4. HTML Helper Methods: They enable you to use HTML helper methods for generating form controls and input fields, reducing the likelihood of markup errors.
5. Automatic Conversion: Model binding automatically converts and assigns posted form data to the model, reducing manual data parsing code.

4. How do you handle multiple models in a Strongly Typed View?

Answer: In ASP.NET MVC, views are typically designed to work with a single model. However, there are a few ways to pass and handle multiple models in a single view:

ViewModel Approach: Create a composite view model that includes all the necessary models.

Example:

public class CompositeViewModel
{
    public MyModel1 Model1 { get; set; }
    public MyModel2 Model2 { get; set; }
}

In the view:

@model Namespace.CompositeViewModel

@Html.LabelFor(m => m.Model1.PropertyName)
@Html.EditorFor(m => m.Model1.PropertyName)

@Html.LabelFor(m => m.Model2.PropertyName)
@Html.EditorFor(m => m.Model2.PropertyName)

Tuple Approach: Use Tuples to combine multiple models.

Example:

public ActionResult MyAction()
{
    var model1 = new MyModel1();
    var model2 = new MyModel2();
    
    return View(Tuple.Create(model1, model2));
}

In the view:

@model Tuple<MyNamespace.MyModel1, MyNamespace.MyModel2>

@Html.LabelFor(m => m.Item1.PropertyName)
@Html.EditorFor(m => m.Item1.PropertyName)

@Html.LabelFor(m => m.Item2.PropertyName)
@Html.EditorFor(m => m.Item2.PropertyName)

5. Can you use Strongly Typed Views with Custom HTML Helpers?

Answer: Yes, you can certainly use strongly typed views with custom HTML helpers. When you create these helpers, you can specify a lambda expression that targets properties of the model, just like built-in HTML helpers.

Example of a Custom HTML Helper:

public static MvcHtmlString CustomInputFor<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, TValue>> expression)
{
    var metadata = ModelMetadata.FromLambdaExpression(expression, html.ViewData);
    var attributes = metadata.DataAnnotationsMetadata.GetMetadataAttributes();
    
    var inputBuilder = new TagBuilder("input")
    {
        Attributes = attributes.ToDictionary(attr => attr.Key, attr => attr.Value)
    };
    
    inputBuilder.Attributes["type"] = "text";
    inputBuilder.Attributes["name"] = ExpressionHelper.GetExpressionText(expression);
    inputBuilder.Attributes["value"] = metadata.Model?.ToString();
    
    return MvcHtmlString.Create(inputBuilder.ToString());
}

Usage in a Strongly Typed View:

@model MyNamespace.MyModel
@Html.CustomInputFor(m => m.PropertyName)

6. What are the advantages of using Razor Syntax with Strongly Typed Views?

Answer: Razor Syntax is the default view engine in ASP.NET MVC, and it offers several advantages when used with strongly typed views:

1. Simplicity: Razor is designed to be less verbose than ASPX syntax, which makes your views cleaner.
2. Implicit Casting: Razor does implicit casting, reducing the need to explicit convert objects, which makes code more compact.
3. Code Readibility: Razor keeps code and markup separate but close together, enhancing readability.
4. Performance: Razor is faster because it uses a code generation strategy rather than parsing at runtime like ASPX.
5. HTML Encoding: Razor handles HTML encoding automatically, providing an added layer of security by preventing XSS (Cross-Site Scripting) attacks.

7. How do you create a Validation Summary in a Strongly Typed View?

Answer: In a strongly typed view, you can create a validation summary by using the @Html.ValidationSummary() helper. This helper displays a summary of validation messages for the model.

Example:

@model MyNamespace.UserModel

@using (Html.BeginForm())
{
    @Html.ValidationSummary(true, "Please correct the following errors:")
    
    <div class="form-group">
        @Html.LabelFor(m => m.UserName)
        @Html.TextBoxFor(m => m.UserName, new { @class = "form-control" })
        @Html.ValidationMessageFor(m => m.UserName)
    </div>
    
    <div class="form-group">
        @Html.LabelFor(m => m.Password)
        @Html.PasswordFor(m => m.Password, new { @class = "form-control" })
        @Html.ValidationMessageFor(m => m.Password)
    </div>
    
    <div class="form-group">
        <input type="submit" value="Register" class="btn btn-primary" />
    </div>
}

In the controller, ensure you trigger validation by returning the view if ModelState.IsValid is false:

[HttpPost]
public ActionResult Register(UserModel model)
{
    if (ModelState.IsValid)
    {
        // Save to database or perform actions
        return RedirectToAction("Success");
    }
    
    // If we got this far, something failed, re-display form
    return View(model);
}

8. How can you access Model Properties in a Strongly Typed View?

Answer: Accessing model properties in a strongly typed view can be done using the Model keyword or through lambda expressions with HTML helpers.

Example:

@model MyNamespace.MyModel

<!-- Using Model -->
<h2>@Model.PropertyName</h2>

<!-- Using Lambda with HTML Helpers -->
@Html.LabelFor(m => m.PropertyName)
@Html.EditorFor(m => m.PropertyName)

<!-- Directly accessing Property -->
<p>@Model.PropertyName</p>

9. Can a Partial View be Strongly Typed in ASP.NET MVC?

Answer: Yes, a partial view in ASP.NET MVC can definitely be strongly typed. You define the model type for a partial view similarly to a full view using the @model directive.

Example of a Strongly Typed Partial View:

@model MyNamespace.UserModel

<div>
    <h2>User Information:</h2>
    <p>Name: @Model.UserName</p>
    <p>Email: @Model.Email</p>
</div>

You can then render this partial view in a different view:

@model MyNamespace.MainViewModel

<!-- Rendering Partial View -->
@Html.Partial("UserPartial", Model.User)

10. How do you handle nested objects in a Strongly Typed View?

Answer: Handling nested objects in a strongly typed view involves creating a model that contains the nested object and then accessing its properties within the view.

Example:

// Nested Model
public class Address
{
    public string City { get; set; }
    public string State { get; set; }
}

// Main Model
public class UserModel
{
    public string UserName { get; set; }
    public Address UserAddress { get; set; }
}

In the view, you can access the nested Address object properties like this:

@model MyNamespace.UserModel

<div>
    <h2>User Information:</h2>
    <p>Name: @Model.UserName</p>
    <p>City: @Model.UserAddress.City</p>
    <p>State: @Model.UserAddress.State</p>
</div>

When using form controls, you need to use proper binding for nested properties to ensure model binding works correctly:

@using (Html.BeginForm())
{
    @Html.LabelFor(m => m.UserName)
    @Html.EditorFor(m => m.UserName)
    
    @Html.LabelFor(m => m.UserAddress.City)
    @Html.EditorFor(m => m.UserAddress.City)
    
    @Html.LabelFor(m => m.UserAddress.State)
    @Html.EditorFor(m => m.UserAddress.State)
    
    <input type="submit" value="Submit" class="btn btn-primary" />
}

This setup ensures that the posted form data is correctly bound to the nested UserAddress object.