:::moniker range="= aspnetcore-5.0"

In this section, classes are added for managing movies in a database. The app's model classes use Entity Framework Core (EF Core) to work with the database. EF Core is an object-relational mapper (O/RM) that simplifies data access. You write the model classes first, and EF Core creates the database.

The model classes are known as POCO classes (from "Plain-Old CLR Objects") because they don't have a dependency on EF Core. They define the properties of the data that are stored in the database.

View or download sample code (how to download).

Add a data model

Visual Studio

1. In Solution Explorer, right-click the RazorPagesMovie project > Add > New Folder. Name the folder Models.

2. Right-click the Models folder. Select Add > Class. Name the class Movie.

3. Add the following properties to the Movie class:

   [!code-csharp]

The Movie class contains:

• The ID field is required by the database for the primary key.

• [DataType(DataType.Date)]: The [DataType] attribute specifies the type of the data (Date). With this attribute:

  • The user isn't required to enter time information in the date field.
  • Only the date is displayed, not time information.

Visual Studio Code

1. Add a folder named Models.
2. Add a class to the Models folder named Movie.cs.

Add the following properties to the Movie class:

[!code-csharp]

The Movie class contains:

• The ID field is required by the database for the primary key.

• [DataType(DataType.Date)]: The [DataType] attribute specifies the type of the data (Date). With this attribute:

  • The user is not required to enter time information in the date field.
  • Only the date is displayed, not time information.

<a name="dc"></a>

Add NuGet packages and EF tools

[!INCLUDE]

Visual Studio for Mac

1. In the Solution Tool Window, control-click the RazorPagesMovie project, and then select Add > New Folder.... Name the folder Models.

2. Control-click the Models folder, and then select Add > New File....

3. In the New File dialog:

   1. Select General in the left pane.
   2. Select Empty Class in the center pane.
   3. Name the class Movie and select New.

4. Add the following properties to the Movie class:

   [!code-csharp]

The Movie class contains:

• The ID field is required by the database for the primary key.

• [DataType(DataType.Date)]: The [DataType] attribute specifies the type of the data (Date). With this attribute:

  • The user is not required to enter time information in the date field.
  • Only the date is displayed, not time information.

DataAnnotations are covered in a later tutorial.

Build the project to verify there are no compilation errors.

Scaffold the movie model

In this section, the movie model is scaffolded. That is, the scaffolding tool produces pages for Create, Read, Update, and Delete (CRUD) operations for the movie model.

Visual Studio

1. Create a Pages/Movies folder:

   1. Right-click on the Pages folder > Add > New Folder.
   2. Name the folder Movies.

2. Right-click on the Pages/Movies folder > Add > New Scaffolded Item.

3. In the Add Scaffold dialog, select Razor Pages using Entity Framework (CRUD) > Add.

4. Complete the Add Razor Pages using Entity Framework (CRUD) dialog:

   1. In the Model class drop down, select Movie (RazorPagesMovie.Models).
   2. In the Data context class row, select the + (plus) sign.
      1. In the Add Data Context dialog, the class name RazorPagesMovie.Data.RazorPagesMovieContext is generated.
   3. Select Add.

The appsettings.json file is updated with the connection string used to connect to a local database.

Visual Studio Code

• Open a command shell to the project directory, which contains the Program.cs, Startup.cs, and .csproj files. Run the following command:

  dotnetcliCopy

  dotnet aspnet-codegenerator razorpage -m Movie -dc RazorPagesMovieContext -udl -outDir Pages/Movies --referenceScriptLibraries -sqlite
  

<a name="codegenerator"></a> The following table details the ASP.NET Core code generator options.

Use the -h option to get help on the dotnet aspnet-codegenerator razorpage command:

dotnet aspnet-codegenerator razorpage -h

For more information, see dotnet aspnet-codegenerator.

[!INCLUDE]

Visual Studio for Mac

1. Create a Pages/Movies folder:

   1. Control-click on the Pages folder > Add > New Folder.
   2. Name the folder Movies.

2. Control-click on the Pages/Movies folder > Add > New Scaffolding....

3. In the New Scaffolding dialog, select Razor Pages using Entity Framework (CRUD) > Next.

4. Complete the Add Razor Pages using Entity Framework (CRUD) dialog:

   1. In the DbContext Class to use: row, name the class RazorPagesMovie.Data.RazorPagesMovieContext.
   2. Select Finish.

The appsettings.json file is updated with the connection string used to connect to a local database.

[!INCLUDE]

[!INCLUDE managed-identities-test-non-production]

Files created and updated

The scaffold process creates the following files:

• Pages/Movies: Create, Delete, Details, Edit, and Index.
• Data/RazorPagesMovieContext.cs

Updated files

• Startup.cs

The created and updated files are explained in the next section.

<a name="pmc"></a>

Create the initial database schema using EF's migration feature

The migrations feature in Entity Framework Core provides a way to:

• Create the initial database schema.
• Incrementally update the database schema to keep it in sync with the application's data model. Existing data in the database is preserved.

Visual Studio

In this section, the Package Manager Console (PMC) window is used to:

• Add an initial migration.
• Update the database with the initial migration.

1. From the Tools menu, select NuGet Package Manager > Package Manager Console.

2. In the PMC, enter the following commands:

   powershellCopy

   Add-Migration InitialCreate
   Update-Database
   

Visual Studio Code / Visual Studio for Mac

• Run the following .NET CLI commands:

  dotnetcliCopy

  dotnet ef migrations add InitialCreate
  dotnet ef database update
  

[!NOTE] For SQLite, column type for the Price field is set to TEXT. This is resolved in a later step.

For SQL Server, the preceding commands generate the following warning: "No type was specified for the decimal column 'Price' on entity type 'Movie'. This will cause values to be silently truncated if they do not fit in the default precision and scale. Explicitly specify the SQL server column type that can accommodate all the values using 'HasColumnType()'."

Ignore the warning, as it will be addressed in a later step.

The migrations command generates code to create the initial database schema. The schema is based on the model specified in DbContext. The InitialCreate argument is used to name the migrations. Any name can be used, but by convention a name is selected that describes the migration.

The update command runs the Up method in migrations that have not been applied. In this case, update runs the Up method in the Migrations/<time-stamp>_InitialCreate.cs file, which creates the database.

Visual Studio

Examine the context registered with dependency injection

ASP.NET Core is built with dependency injection. Services, such as the EF Core database context, are registered with dependency injection during application startup. Components that require these services (such as Razor Pages) are provided via constructor parameters. The constructor code that gets a database context instance is shown later in the tutorial.

The scaffolding tool automatically created a database context and registered it with the dependency injection container.

Examine the Startup.ConfigureServices method. The highlighted line was added by the scaffolder:

[!code-csharp]

The RazorPagesMovieContext coordinates EF Core functionality, such as Create, Read, Update and Delete, for the Movie model. The data context (RazorPagesMovieContext) is derived from Microsoft.EntityFrameworkCore.DbContext. The data context specifies which entities are included in the data model.

[!code-csharp]

The preceding code creates a DbSet<Movie> property for the entity set. In Entity Framework terminology, an entity set typically corresponds to a database table. An entity corresponds to a row in the table.

The name of the connection string is passed in to the context by calling a method on a DbContextOptions object. For local development, the Configuration system reads the connection string from the appsettings.json file.

Visual Studio Code / Visual Studio for Mac

Examine the Up method.

<a name="test"></a>

Test the app

1. Run the app and append /Movies to the URL in the browser (http://localhost:port/movies).

   If you receive the following error:

   consoleCopy

   SqlException: Cannot open database "RazorPagesMovieContext-GUID" requested by the login. The login failed.
   Login failed for user 'User-name'.
   

   You missed the migrations step.

2. Test the Create link.

   [!NOTE] You may not be able to enter decimal commas in the Price field. To support jQuery validation for non-English locales that use a comma (",") for a decimal point and for non US-English date formats, the app must be globalized. For globalization instructions, see this GitHub issue.

3. Test the Edit, Details, and Delete links.

[!INCLUDEs]

The next tutorial explains the files created by scaffolding.

Next steps

[!div class="step-by-step"] Previous: Get Started Next: Scaffolded Razor Pages

:::moniker-end