In this article I will explain with an example, how to update data into database using Dapper library in ASP.Net Core Razor Pages.
Note: For beginners in ASP.Net Core (.Net Core 7) Razor Pages, please refer my article ASP.Net Core 7 Razor Pages: Hello World Tutorial with Sample Program example.
 
 

Installing Dapper package using Nuget

In order to install Dapper library using Nuget, please refer my article Install Dapper from Nuget in Visual Studio.
 
 

Database

I have made use of the following table Customers with the schema as follows.
Update using Dapper in ASP.Net Core Razor Pages
 
I have already inserted few records in the table.
Update using Dapper in ASP.Net Core Razor Pages
 
Note: You can download the database table SQL by clicking the download link below.
          Download SQL file
 
 

Model

The Model class consists of following properties.
public class CustomerModel
{
    public int CustomerId { get; set; }
    public string Name { get; set; }
    public string Country { get; set; }
}
 
 

Namespaces

You will need to import the following namespaces.
using Dapper;
using System.Data.SqlClient;
 
 

Razor PageModel (Code-Behind)

The PageModel consists of following Handler methods.

Handler Method for handling GET operation

This Handler method is left empty as it is not required.
 

Handler Method for handling POST operation

This Handler method accepts CustomerModel class object as a parameter.
Inside this Handler method, first the connection is read from the ConnectionStrings section of the AppSettings.json file.
Note: For more details on how to read Connection String from AppSettings.json, please refer my article .Net Core 7: Read Connection String from AppSettings.json file.
 
Then, the SQL query and CustomerModel class object is passed to the Execute method of the Dapper library which then updates the record in the Customers Table.
Note: For more details on Execute method, please refer my article Understanding Dapper Execute in C# and VB.Net.
 
Finally, based on whether the record is updated or not an appropriate message is set into ViewData object.
public class IndexModel : PageModel
{
    public IConfiguration Configuration { get; set; }
 
    public CustomerModel Customer { get; set; }
 
    public IndexModel(IConfiguration configuration)
    {
        this.Configuration = configuration;
    }
    public void OnGet()
    {
    }
 
    public void OnPostSubmit(CustomerModel customer)
    {
        string sql = "UPDATE Customers SET Name=@Name, Country=@Country WHERE CustomerId=@CustomerId";
        string constr = this.Configuration.GetSection("ConnectionStrings")["MyConn"];
        using (SqlConnection con = new SqlConnection(constr))
        {
            int i = con.Execute(sql, customer);
            if (i > 0)
            {
                ViewData["Message"] = "Customer record updated.";
            }
            else
            {
                ViewData["Message"] = "Customer not found.";
            }
        }
    }
}
 
 

Razor Page (HTML)

HTML Markup

Inside the Razor Page, the ASP.Net TagHelpers is inherited.
The HTML Razor Page consists of an HTML Form consisting HTML Table, which contains of three TextBoxes and a Submit Button.
The Submit Button has been set with the POST Handler method using the asp-page-handler attribute.
Note: In the Razor PageModel, the Handler method name is OnPostSubmit but here it will be specified as Submit when calling from the Razor HTML Page.
 

Submitting the Form

When the Submit Button is clicked then, the ViewData object is checked for NULL and if it is not NULL then, the value of the ViewData object is displayed using JavaScript Alert Message Box.
@page
@model Dapper_Update_Core_Razor.Pages.IndexModel
@addTagHelper*, Microsoft.AspNetCore.Mvc.TagHelpers
@{
    Layout = null;
}
 
<!DOCTYPE html>
 
<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>Index</title>
</head>
<body>
    <form method="post">
        <table cellpadding="1" cellspacing="1">
            <tr>
                <td>
                    Id<br />
                    <input type="text" asp-for="Customer.CustomerId" style="width: 60px;" />
                </td>
                <td>
                    Name<br />
                    <input type="text" asp-for="Customer.Name" style="width: 150px;" />
                </td>
                <td>
                    Country:<br />
                    <input type="text" asp-for="Customer.Country" style="width: 150px;" />
                </td>
                <td>
                    <br />
                    <input type="submit" value="Update" asp-page-handler="Submit" />
                </td>
            </tr>
        </table>
    </form>
    @if (ViewData["Message"] != null)
    {
        <script type="text/javascript">
            window.onload = function () {
                alert("@ViewData["Message"]");
            };
        </script>
    }
</body>
</html>
 
 
 

Screenshot

Update using Dapper in ASP.Net Core Razor Pages
 
 

Downloads

Download Code