Category: Entity Framework

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JumpStart # 17–Difference between IEnumerable<T> and IQueryable<T> in EntityFramework SQL

IQueryable basically generates the complete expression tree and then executes it to get results, where are it is not true in IEnumerable scenario. But still IQueryable is inherited from IEnumerable. IQueryable’s extension methods take expressions based on which expression trees are build, while for IEnumerable’s extensions methods takes functions based on which results are enumerated and published. From afore said reasons, IEnumerable is better on Collections stored in memory, where as IQueryable can optimize performance of Remote Data Sources like Databases.

11

ASP.Net MVC–Simple Application Security using Password Hashing before storing it to Database

The intended application got some secured products in the Sql DB (here the table is Products). Users can login to the DB and can only retrieve products thorough MVC Application. So User first needs to Register to the application, then he can login to the application to retrieves the secured information of the products.

The main attention of the complete process flow is “Registration”, especially Password field. Storing Password as a string into DB is considered as not a good practice, so first we generate a Password Salt using Cryptography, then we use the original Password String along with Password Salt to hash it into a more secured format using a Hashing algorithm. and finally it is stored in the Users table of Sql DB.

While Authenticating User, we get the Password String from User login, then check the DB for Username, get the User Entity from the DB, fetch the Password Salt associated with the User, Combine the Password string and Password Salt to generate the Password Hash, then finally cross check the generated Hash with that of the DB version. If both matches, Authenticate the user or else notify him as Invalid Login.

3

Implementing MVP Pattern using UserControls with WCF Database Operations in Entity Framework and LINQ – Part III

In this part of the tutorial, we carry on with the construction of MVP Pattern. First we start with the creation of View interfaces for the UserControls (which we created in PART II). Then we create the presenter classes, which will take the corresponding instances of views and then manipulate the view using Model classes (there by achieving code portability). Once we are done with the presenter classes, we implement the View interfaces in the codebehind of the UserControls. Finally we create a sample ASP.Net web page (typically webform), and use the UserControls for database transactions.

4

Implementing MVP Pattern using UserControls with WCF Database Operations in Entity Framework and LINQ – Part II

In this part of the tutorial – We first code for the CustomerService.cs by implementing ICustomerService.cs interface. We use LINQ queries to code database transactions. Then we create a host application (here it is a Console application) which operates the WCF service. Then we create a sample website for implementing MVP Pattern to access WCF. In the website, we implement some UserControls for fetching/updating/deleting records from the database.

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Implementing MVP Pattern using UserControls with WCF Database Operations in Entity Framework and LINQ – PART I

First we create a database – ‘CustomersDB’ – with a table in it – ‘Customers’. This table Customers holds the basic data related to each and every customer. Then we create the entity model for this CustomersDB using ADO.Net Entity Framework. After that we create a WCF service with minimal end point configuration to access ServiceContracts which do basic database operations. Instead of coding the data access methods (of the class implementing ServiceContract) in traditional ADO.Net queries, we tend to use LINQ for the same. Once the service is ready, we host it using a Console App. With this we complete the backend of the article. Now we implement the MVP pattern for better separation of UI from its code with the help of presenter class. So we create an interface for both model and view and then implement them in their respective class. Finally we create a UI with some UserControls in it for adding/editing/deleting customers from the front end.

11

Create a Simple WCF Service Client against Pubs Database using EF, LINQ – Part II

1) In this tutorial (which is PART – II), we create a small website in ASP.Net 4.0 and we shall use a WebForm (named: PubsServiceTestPage.aspx) as a client to our service (which we created in former tutorial).
2) We Use the inline model of Webform (not the codebehind model).
3) We perform the actions using our client like, Getting all the Authors and display them in the Dropdownlist for selections, Selecting a Author and display his corresponding books using a Repeater, Modify and save the book details back to database etc.
4) To test the Client, we need the service to be running in the server, that can be simply manipulated by starting another instance of VS 2010 and running (Ctrl + F5) the PubsService.svc.cs.

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Create a Simple WCF service against Pubs Database using EF, LINQ – Part I

1) In this tutorial we create a simple WCF service which is used to retrieve and save data from Pubs Database (Microsoft sample database).
2) The service also demos on how to use EF 4.0 and LINQ against database coding, with no requirement of writing SQL queries.
3) The continuation of this tutorial shows on how to create a client (say a WebForm in a website) to utilize this service.