/ASP.NET-Core-MVC-Trial-2

Primary LanguageC#

ASP.NET Core MVC RESTful API using EF Core DB First Approach

Basic RESTful CRUD app using ASP.NET Core 3.1 MVC and Entity Framework Core DB First Approach

Notes on creating models via EF Core's scaffolding

  1. First, you need to have Microsoft.EntityFrameworkCore.Tools to have access to the Scaffold-DbContext command.
  2. You also need to install a database provider for the database you are using. For this project, I'm using Microsoft SQL Server Express so I needed to have the Microsoft.EntityFrameworkCore.SqlServer data provide. These packages can be installed via the Nuget Package Manager

Package setup for EF Core

  1. Once you've installed the necessary packages, you now have access to the Scaffold-DbContext command in the Package Manager Console. See the documentation on Scaffold-DbContext here. Here is another tutorial link on the usage of Scaffold DbContext.

  2. To use the Scaffold-DbContext command, you also need to know the connection string for your database. The Scaffold-DbContext has two positional arguments - the connection string and the database provider (for this case, the database provider used is Microsoft.EntityFrameworkCore.SqlServer). The code below shows an example on how to use the Scaffold-DbContext in the Package Manager Console. The -OutputDir command sets the directory where the model files will be put in. In this case, it's placed under the Models folder.

    • Example usage of Scaffold-DbContext. In this example, we are generating models for all of the tables in the selected database by default and the output directory is set to Models via the -OutputDir optional argument. In this example, we are also using the -UseDatabaseNames option so that the generated table and column names in our models match exactly as what appears in the database. Another option that we are using here is the -Context option which specifies the name of the DbContext class to generate. So after running this scaffold, we should have an EmployeeContext.cs DbContext class inside our Models folder.

      Scaffold-DbContext "Data Source=LAPTOP-VRPV043O\SQLEXPRESS;Initial Catalog=testEFCore;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False;" Microsoft.EntityFrameworkCore.SqlServer -OutputDir Models -UseDatabaseNames -Context "EmployeeContext"

    • In this example, we are only generating a model for the Skills table using the -Tables optional argument

      Scaffold-DbContext "Data Source=LAPTOP-VRPV043O\SQLEXPRESS;Initial Catalog=testEFCore;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False;" Microsoft.EntityFrameworkCore.SqlServer -OutputDir Models -UseDatabaseNames -Context "EmployeeContext" -Tables "Skills"

    • If for example, you've already run the Scaffold-DbContext and you want to add another table to the models, you can use the -Force option to overwrite the existing DbContext. Note that you should add the previous tables already generated before in the -Tables option.

      Scaffold-DbContext "Data Source=LAPTOP-VRPV043O\SQLEXPRESS;Initial Catalog=testEFCore;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False;" Microsoft.EntityFrameworkCore.SqlServer -OutputDir Models -UseDatabaseNames -Context "EmployeeContext" -Tables "Skills","Employees" -Force

Notes on setting up Connection String in the dbContext class and the Startup.cs file

  1. Add the following in your Startup.cs

    • Add this in Startup.ConfigureServices() method

      ConnectionString = Configuration.GetConnectionString("testDB");
services.AddDbContext<EmployeeContext>(options => options.UseSqlServer(ConnectionString));

    • Add a static ConnectionString property. This is used to pass the ConnectionString to the DbContext.

      private static string ConnectionString { get; set; }

    • Add a getter method for the ConnectionString property.

      public static string GetConnectionString()
{
  return ConnectionString;
}

  2. In the DbContext file (in this project, it's EmployeeContext class), change the OnConfiguring method to use the ConnectionString from startup.cs

    optionsBuilder.UseSqlServer(Startup.GetConnectionString());

Notes on building REST APIs using ASP.NET Core

  1. HTTP PUT and DELETE are available by default in ASP.NET Core MVC unlike in ASP.NET MVC 5.
  2. See this link on the setup of the Startup.cs for REST APIs in ASP.NET Core

Todo:

  1. When deleting a skill resource, update also the employees with that skill (i.e. set to null value)