Dapper Extensions Read Data


Most of the applications would perform the basic operation to retrieve data from the database and display the results. We have two tables in the database that contains the following data.

Database data

To retrieve the data from the database using Dapper Extensions, let's create two classes called Author and Book.

Here is the implementation of the Author class.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace DapperExtensionsDemo
{
    public class Author
    {
        public int Id { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public List<Book> Books { get; set; }
    }
}

The following is the implementation of the Book class.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace DapperExtensionsDemo
{
    public class Book
    {
        public int Id { get; set; }
        public string Title { get; set; }
        public string Category { get; set; }
        public int AuthorId { get; set; }
    }
}

In the Program class, define the static variable, which contains the connection string of the database.

static string ConnectionString = @"Data Source=(localdb)\ProjectsV13;Initial Catalog=BookStoreDb;Integrated Security=True;";

The first step is to create a member of type IDbConnection with the SqlConnection by passing the connection string.

private static List<Author> GetAllAuthors()
{
    using (IDbConnection db = new SqlConnection(ConnectionString))
    {
        db.Open();
        List<Author> authors = db.GetList<Author>().ToList();
        db.Close();

        return authors;
    }
}

The GetList extension method enables you to retrieve data from the database and populate data in your object model.

It also provides a Get method to retrieve a single record, as shown below.

private static Author GetAuthor(int id)
{
    using (IDbConnection db = new SqlConnection(ConnectionString))
    {
        db.Open();
        Author author = db.Get<Author>(id);
        db.Close();

        return author;
    }
}

Now call the above methods from the Main method.

static void Main(string[] args)
{
    Author author1 = GetAuthor(2);

    Console.WriteLine(author1.FirstName + " " + author1.LastName);

    List<Author> authors = GetAllAuthors();

    foreach (var author in authors)
    {
        Console.WriteLine(author.FirstName + " " + author.LastName);
    }
}

Let's execute the above code, and you will see the following output.

William Shakespeare
Cardinal Tom B. Erichsen
William Shakespeare
Robert T. Kiyosakiy