In this blog, I am going to provide a walk-through on developing a web application using ASP.NET Core 3.0, connecting it to a database (database-first) using the Entity Framework Core 3.0 command, and performing CRUD operations using scaffolding (code generator). I am going to develop a sample application for inventory management with basic operations.
ASP.NET Core is a web framework from Microsoft. It is an open-source, cross-platform, cloud-optimized web framework that runs on Windows using .NET Framework and .NET Core, and on other platforms using .NET Core. It is a complete rewrite that unites ASP.NET MVC and Web API into a single programming model and removes system-related dependencies. This helps in deploying applications to non-Windows servers and improves performance.
This blog post will discuss the following:
- Database creation
- Create an ASP.NET Core application
- Install necessary NuGet packages
- Connect application to database
- Scaffold CRUD operations
- Run application
Note: In this demo application, I have used ASP.NET Core 3.0 Preview 8, Entity Framework Core 3.0 Preview 8, with Visual Studio 2019 16.3.0 Preview 2.0.
A .NET Core application can be developed using these IDEs:
- Visual Studio
- Visual Studio Code
- Command Prompt
Here, I am using Visual Studio to build the application. Be sure that the necessary software is installed:
- Visual Studio 2019 16.3.0 Preview 2.0
- NET Core 3.0 Preview 8
- SQL Server 2017
Let’s create a database on your local SQL Server. I hope you have installed SQL Server 2017 in your machine (you can use SQL Server 2008, 2012, or 2016, as well).
Step 1: Open Visual Studio 2019.
Step 2: Open SQL Server Object Explorer and click Add SQL Server.
Adding SQL Server
Step 3: Here we have an option to choose from the local machine’s SQL Server, connected via network, and the Azure SQL database. I have chosen the local SQL Server instance. I provide the SQL Server details and click Connect. The SQL Server will be listed in Explorer.
Establishing connection to the database server
SQL Server listed in Solution Explorer
Step 4: Right-click on a database node and create a new database (Inventory).
Step 5: Now we have the database in place. Click on our database and choose New Query.
Step 6: For this application, I am going to create a table called Products with basic attributes. Paste the following SQL query into the Query window to create a Products table.
Create Table Products( ProductId BigInt Identity(1,1) Primary Key, Name Varchar(100) Not Null, Category Varchar(100), Color Varchar(20), UnitPrice Decimal Not Null, AvailableQuantity BigInt Not Null, CratedDate DateTime Default(GetDate()) Not null)
Step 7: Click the Run icon to create the table. Now we have the table needed for our application.
Create an ASP.NET Core application
Follow these steps to create an ASP.NET Core application.
Step 1: In Visual Studio 2019, click on File -> New -> Project.
Step 2: Choose the Create a new project option.
Step 3: Select the ASP.NET Core Web Application template.
Step 4: Enter project name and click Create.
Step 5: Select .NET Core and ASP.NET Core 3.0 and choose the Web Application (Model-View-Controller) template.
Uncheck the Configure for HTTPS under the Advanced options (in a development environment, we have no need of SSL).
Click Create. Then the sample ASP.NET Core application will be created with this project structure.
Install NuGet packages
The following NuGet packages should be added to work with the SQL Server database and scaffolding. Run these commands in Package Manager Console:
- Install-Package Microsoft.VisualStudio.Web.CodeGeneration.Design -Version 3.0.0-preview8-19413-06 This package helps generate controllers and views.
- Install-Package Microsoft.EntityFrameworkCore.Tools -Version 3.0.0-preview8.19405.11 This package helps create database context and a model class from the database.
- Install-Package Microsoft.EntityFrameworkCore.SqlServer -Version 3.0.0-preview8.19405.11 The database provider allows Entity Framework Core to work with SQL Server.
ASP.NET Core has a feature called scaffolding, which uses T4 templates to generate code of common functionalities to help keep developers from writing repeat code. We use scaffolding to perform the following operations:
- Generate entity POCO classes and a context class for the database.
- Generate code for create, read, update, and delete (CRUD) operations of the database model using Entity Framework Core, which includes controllers and views.
Connect application with database
Run the following scaffold command in Package Manager Console to reverse engineer the database to create database context and entity POCO classes from tables. The scaffold command will create POCO class only for the tables that have a primary key.
Scaffold-DbContext “Server=ABCSERVER;Database=Inventory;Integrated Security=True” Microsoft.EntityFrameworkCore.SqlServer -OutputDir Models
- Connection—Sets connection string of the database.
- Provider—Sets which provider to use to connect database.
- OutputDir—Sets the directory where the POCO classes are to be generated.
In our case, the Products class and Inventory context class will be created.
Open the Inventory Context class file. You will see the database credentials are hard coded in the OnConfiguring method.
It’s not good practice to have SQL Server credentials in C# class, considering the security issues. So, remove this OnConfiguring method from context file.
And move the connection string to the appsettings.json file.
Then we can register the database context service (InventoryContext) during application startup. In the following code, the connection string is read from the appsettings file and passed to the context service.
Then this context service is injected with the required controllers via dependency injection.
Perform CRUD operations
Now we set up the database and configure it to work with Entity Framework Core. We’ll see how to perform CRUD operations.
Right-click on the controller folder, select add new item, and then select controller. Then this dialog will be displayed.
Select the MVC Controller with views, using Entity Framework option and click Add.
We need to choose a database model class and data context class, which were created earlier, and click Add.
That’s it, we’re done. The scaffolding engine uses T4 templates to generate code for controller actions and views in their respective folders. This is the basic version of code; we can modify it as needed.
Please find the files created,
Now we have fully functional CRUD operations on the Products table.
Then, change the default application route to load the Products Controller instead of the home controller. Open the Startup.cs file and under the Configure method, change the default controller to Products.
With the help of the scaffolding engine, developers need not write CRUD operations for each database model.
Click Run to view the application. A new browser tab will open and we’ll be able to see the product listing page. Since there is no product in the inventory, it’s empty.
Click Create New to add new products to the inventory.
After entering the details, click Create. Now we should see newly created products in the listing page as in the following screenshot. I have added three more products.
Click Details to view the product details.
Click Edit to update product details.
Click Delete to delete a product. Confirmation will be requested before it’s deleted from the database.
Without writing a single line of code, we are able to create an application with basic CRUD operations with the help of the scaffolding engine.
I have shared the sample application in this GitHub location. Extract the application, change the connection string in the appsettings.json file that points to your SQL Server, and run the application.
In this blog, we have learned how to create an ASP.NET Core application and connect it to a database to perform basic CRUD operations using Entity Framework Core 3.0 and a code generation tool. I hope it was useful. Please share your feedback in the comments section below.
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