ASP.NET MVC Series For Beginners: Part 2

The Model provides specific results as an output upon the request of the View to represent.

FIGURE 6: DEFINING MVC

Models

Returning to our project, we have created the preceding. Have a look at Models.

• A MVC Model is nothing but a class.
  
  Yes, it is true. Models are nothing, just typical classes. We can create a simple class and add properties and many things you want and then use this class as a Model. Whenever you create a Model just ensure it should be created under the Models folder just to make a standard approach.
  
• Both Controllers and Views can access Models.
• A Model can be used to pass data from a Controller to a View.

Add a Model

As we know Model is a class. In Solution Explorer move to the Models folder and add a new class, here is a sample Model:

Have a look into the preceding class, we have certain properties in the Student class. Now, think of a Student table (that is in your database). This table has a few columns. Now, return to our class defined above. StudentModel is a representation of our Student table and all the properties are the representation of all the table columns.

Attributes at a glance

After creating our data models, in other words after creation of our representation of tables, we need to control all the properties, like what kind of Data Type they could accept, how much length they could accept and so on.

The following are the main attributes available:

• Attributes to check DataTypes
  
  Let's add one more property in our model above.
  
  
  
  We added DateOfBirth and defined the type as a DateTime. Just think, we need only a Date and we are defining DateTime. For this we have Data Attributes.
  
  To do the same just add the following namespace:
  
  
  
  Now, you can add a Data Type attribute of DateType.Date as:
  
  
  
  There are many other important data types available:
  
  
  
  Let's have a look into the DataType attribute class: [ref.: http://goo.gl/4GvSlb ]
  It contains properties and methods. We are not going into depth, go to the link referred to above to get more.
  
• Attributes to Display
  
  Sometimes, we have requirements to display our data in some format that does not provide or is not a default format. To display in such a format we have Display attributes.
  
  Think; we need to show our DateOfBirth in some custom date format:
  
  
  
  Above, we applied a new DisplayFormat attribute to display our date in the format of yyyy-MM-dd (for example 2014-12-28) with the special thing ApplyFormatInEditMode = true. What does it specify? This is because we want to keep the same format during our editing. Cool, these attributes are really awesome!
  
• Attributes for validations
  
  • Required
    
    Think of a scenario where we need to force the user to enter the field. We use the Required attribute for that. In our above example we want FirstName in every scenario. So, we just use the attribute to make it required.
    
    
    
    Now, with this our user must enter a FirstName.
    
  • Length
    
    Think of a scenario that we need to limit the length for the FirstName.
    
    
    
    Now, the user must be limited by a maximum of 25 characters for First Name, otherwise the user will get an error message as defined.
    
    
    
    Also, we can define a minimum of characters for properties.
    
    
    
  • RegularExpression
    
    It allows us to use our own custom RegulatExpression. Let's say we need a Alphanueric Enrollment Number like:
    
    
    
    For more details of the Customization Model and more complex models refer to: http://goo.gl/8ZQCQP.

Q & A

In this session we have covered a great Q&A section, I am trying to cover each and every question. Please add any question I missed.

I do not have Visual Studio 2015 installed on my System.

I am not going into depth about this, refer to this article for the installation of VS 2015: http://goo.gl/BGFWYw.

Choosing ASP.NET MVC over ASP.NET Web-Forms

There are numerous reasons to choose ASP.Net for web development over ASP.Net Web forms including the following:

• ASP.NET MVC is a web framework and is based on the MVC pattern.
• No view state (performance is better in ASP.NET MVC).
• Completely testable.
• Integration with the client side (easily handshake with client-side scripting like jQuery and so on).

Flexibility (provides various view engines that render HTML; the Razor View Engine is the most famous).

Let's think of a scenario where we are writing an application in ASP.NET Web Forms and there are two classes for one thing. Let's say a default page that includes Default.aspx and Default.aspx.cs pages and our designer page.

A designer page has all the server control and aspx pages that contain visualization of our server controls (UI part) and finally our cs page (class) contains all the functionality and other logics. Our class is based on the ASP.NET Page life cycle (for complete details refer to: MSDN).

We can't completely test our Web Forms. To make it properly testable at some instance, we need to implement some other UI Design pattern viz. MVP, MVVM, MVC.

If we are implementing the MVC UI Pattern in our Web Forms then why don't we use the ASP.NET MVC framework that is already using this pattern and provides everything required to create web apps.

Define Model View Controller

Here is the conclusion of what we discussed (for the ASP.Net MVC framework).

Models

• The MVC model is typically a class (of C# or VB.NET).
• Both the Controller and the View can access the Model.
• A Model can be used to pass data from the Controller to the View.
• The main purpose of a View is to display the data in a page using the Model.

Views

• A View is nothing but a page (you can say a web page) and it does not have any code-behind.
• All page-specific HTML generation and formatting can be done inside the View.
• A request to a view can be made only from a Controller's action method.

Controllers

• A Controller is typically a class (of C# or VB.Net) and inherits from “system.mvc.controller”.
• Within this class, methods can be implemented and called as action methods. These are responsible for responding to the browser and/or for calling Views.
• A Controller class can access and use a Model class to pass data to the Views.

Routes

A system works on a pattern matching mechanism. A route matches an incoming request to meet a specific pattern and allows once matched else denied.

Conclusion

In this article I tried to cover all the things we discussed about Models and Demo applications. Also, I included some questions/discussions and answers. I am continuously receiving emails with more questions and I will provide more questions/discussions and answers very soon.

Until now, we discussed Models, data attributes and complex models.

We will continue in the next session.