Entity Data Model Update Records SqlCreating Model Classes with the Entity Framework (C#)by Microsoft. In this tutorial, you learn how to use ASP. NET MVC with the Microsoft Entity Framework. You learn how to use the Entity Wizard to create an ADO. NET Entity Data Model. Over the course of this tutorial, we build a web application that illustrates how to select, insert, update, and delete database data by using the Entity Framework. The goal of this tutorial is to explain how you can create data access classes using the Microsoft Entity Framework when building an ASP. NET MVC application. This tutorial assumes no previous knowledge of the Microsoft Entity Framework. By the end of this tutorial, you'll understand how to use the Entity Framework to select, insert, update, and delete database records. The Microsoft Entity Framework is an Object Relational Mapping (O/RM) tool that enables you to generate a data access layer from a database automatically. The Entity Framework enables you to avoid the tedious work of building your data access classes by hand. The s table records suppliers. It has 3 defined columns: sno -- supplier number, an unique identifier that is the primary key name -- the name of the supplier. EdNA (Education Names and Addresses) can be used to find name, address, administrator, and related information about the educational entities that PDE serves. In this tutorial, you learn how to use ASP.NET MVC with the Microsoft Entity Framework. You learn how to use the Entity Wizard to create an ADO.NET Entity Data Model. Entity–attribute–value model (EAV) is a data model to encode, in a space-efficient manner, entities where the number of attributes (properties, parameters) that. This tutorial shows how to build an entity and how to consume some out-of-band (OOB) entities in an integration scenario. You will also preview how these data. This article describes how to update multiple records at a time in ASP.NET MVC Applications. Update an Entity with ObjectContext: This article uses older version of EF Visit basic tutorials section if you are using Entity Framework 5.0 with VS2012. The Hierarchical Data Model. The Hierarchical Data Model structures data in a tree of records, with each record having one parent record and many children. DbContext is usually used with a derived type that contains DbSet <TEntity> properties for the root entities of the model. These sets are automatically initialized. In the late 1970s data-flow diagrams (DFDs) were introduced and popularized for structured analysis and design (Gane and. In order to illustrate how you can use the Microsoft Entity Framework with ASP. NET MVC, we'll build a simple sample application. We'll create a Movie Database application that enables you to display and edit movie database records. This tutorial assumes that you have Visual Studio 2. Visual Web Developer 2. Service Pack 1. You need Service Pack 1 in order to use the Entity Framework. You can download Visual Studio 2. Service Pack 1 or Visual Web Developer with Service Pack 1 from the following address: https: //www. Note. There is no essential connection between ASP. NET MVC and the Microsoft Entity Framework. There are several alternatives to the Entity Framework that you can use with ASP. NET MVC. For example, you can build your MVC Model classes using other O/RM tools such as Microsoft LINQ to SQL, NHibernate, or Sub. Sonic. Creating the Movie Sample Database. The Movie Database application uses a database table named Movies that contains the following columns: Column Name. Data Type. Allow Nulls? Is Primary Key? Idint. False. True. Titlenvarchar(1. False. False. Directornvarchar(1. False. False. You can add this table to an ASP. NET MVC project by following these steps: Right- click the App. Right- click the Movies table and select the menu option Show Table Data. You can enter fake movie data into the grid that appears. Creating the ADO. NET Entity Data Model. In order to use the Entity Framework, you need to create an Entity Data Model. You can take advantage of the Visual Studio Entity Data Model Wizard to generate an Entity Data Model from a database automatically. Follow these steps: Right- click the Models folder in the Solution Explorer window and select the menu option Add, New Item. In the Add New Item dialog, select the Data category (see Figure 1). Select the ADO. NET Entity Data Model template, give the Entity Data Model the name Movies. DBModel. edmx, and click the Add button. Clicking the Add button launches the Data Model Wizard. In the Choose Model Contents step, choose the Generate from a database option and click the Next button (see Figure 2). In the Choose Your Data Connection step, select the Movies. DB. mdf database connection, enter the entities connection settings name Movies. DBEntities, and click the Next button (see Figure 3). In the Choose Your Database Objects step, select the Movie database table and click the Finish button (see Figure 4). After you complete these steps, the ADO. NET Entity Data Model Designer (Entity Designer) opens. Figure 1 – Creating a new Entity Data Model. Figure 2 – Choose Model Contents Step. Figure 3 – Choose Your Data Connection. Figure 4 – Choose Your Database Objects. Modifying the ADO. NET Entity Data Model. After you create an Entity Data Model, you can modify the model by taking advantage of the Entity Designer (see Figure 5). You can open the Entity Designer at any time by double- clicking the Movies. DBModel. edmx file contained in the Models folder within the Solution Explorer window. Figure 5 – The ADO. NET Entity Data Model Designer. For example, you can use the Entity Designer to change the names of the classes that the Entity Model Data Wizard generates. The Wizard created a new data access class named Movies. In other words, the Wizard gave the class the very same name as the database table. Because we will use this class to represent a particular Movie instance, we should rename the class from Movies to Movie. If you want to rename an entity class, you can double- click on the class name in the Entity Designer and enter a new name (see Figure 6). Alternatively, you can change the name of an entity in the Properties window after selecting an entity in the Entity Designer. Figure 6 – Changing an entity name. Remember to save your Entity Data Model after making a modification by clicking the Save button (the icon of the floppy disk). Behind the scenes, the Entity Designer generates a set of C# classes. You can view these classes by opening the Movies. DBModel. Designer. Solution Explorer window. Don't modify the code in the Designer. Entity Designer. If you want to extend the functionality of the entity classes defined in the Designer. Selecting Database Records with the Entity Framework. Let's start building our Movie Database application by creating a page that displays a list of movie records. The Home controller in Listing 1 exposes an action named Index(). The Index() action returns all of the movie records from the Movie database table by taking advantage of the Entity Framework. Listing 1 – Controllers\Home. Controller. csusing System. Linq. using System. Web. Mvc. using Movie. Entity. App. Models. Movie. Entity. App. Controllers. . The constructor initializes a class- level field named . The expression . The To. List() method is used to convert the set of movies into a generic collection of Movie objects (List< Movie> ). The movie records are retrieved with the help of LINQ to Entities. The Index() action in Listing 1 uses LINQ method syntax to retrieve the set of database records. If you prefer, you can use LINQ query syntax instead. The following two statements do the very same thing: View. Data. Model = . There is no difference in performance between the two approaches – the only difference is style. The view in Listing 2 is used to display the movie records. Listing 2 – Views\Home\Index. Page Language=. Notice that an Edit and Delete link is displayed next to each record. Furthermore, an Add Movie link appears at the bottom of the view (see Figure 7). Figure 7 – The Index view. The Index view is a typed view. The Index view includes a & lt; %@ Page %> directive with an Inherits attribute that casts the Model property to a strongly typed generic List collection of Movie objects (List< Movie). Inserting Database Records with the Entity Framework. You can use the Entity Framework to make it easy to insert new records into a database table. Listing 3 contains two new actions added to the Home controller class that you can use to insert new records into the Movie database table. Listing 3 – Controllers\Home. Controller. cs (Add methods)public Action. Result Add(). . The view contains a form for adding a new movie database record (see Figure 8). When you submit the form, the second Add() action is invoked. Notice that the second Add() action is decorated with the Accept. Verbs attribute. This action can be invoked only when performing an HTTP POST operation. In other words, this action can only be invoked when posting an HTML form. The second Add() action creates a new instance of the Entity Framework Movie class with the help of the ASP. NET MVC Try. Update. Model() method. The Try. Update. Model() method takes the fields in the Form. Collection passed to the Add() method and assigns the values of these HTML form fields to the Movie class. When using the Entity Framework, you must supply a . The action verifies that both the Title and Director properties have values. If there is a validation error, then a validation error message is added to Model. State. If there are no validation errors then a new movie record is added to the Movies database table with the help of the Entity Framework. The new record is added to the database with the following two lines of code. The second line of code saves whatever changes have been made to the Movies being tracked back to the underlying database. Figure 8 – The Add view. Updating Database Records with the Entity Framework. You can follow almost the same approach to edit a database record with the Entity Framework as the approach that we just followed to insert a new database record. Listing 4 contains two new controller actions named Edit(). The first Edit() action returns an HTML form for editing a movie record. The second Edit() action attempts to update the database. Listing 4 – Controllers\Home. Controller. cs (Edit methods)public Action. Result Edit(int id). The following LINQ to Entities statement grabs the first database record that matches a particular Id: var movie. To. Update = . Notice that a white list is supplied to specify the exact properties to update. Next, some simple validation is performed to verify that both the Movie Title and Director properties have values. If either property is missing a value, then a validation error message is added to Model. State and Model. State. Is. Valid returns the value false. Finally, if there are no validation errors, then the underlying Movies database table is updated with any changes by calling the Save. Changes() method. When editing database records, you need to pass the Id of the record being edited to the controller action that performs the database update. Otherwise, the controller action will not know which record to update in the underlying database. The Edit view, contained in Listing 5, includes a hidden form field that represents the Id of the database record being edited. Listing 5 – Views\Home\Edit. Page Language=. You can use the controller action in Listing 6 to delete a particular database record. Listing 6 - - \Controllers\Home.
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