In this article I will explain with an example, how to upload, read and display Excel file data using OLEDB in ASP.Net Core (.Net Core 7) MVC.
The uploaded Excel file data will be read using OLEDB library and the read data will be displayed in View using HTML Table (Grid) format.
Note: For beginners in ASP.Net Core (.Net Core 7), please refer my article ASP.Net Core 7: Hello World Tutorial with Sample Program example.
 
 

Download System.Data.OleDb DLL

There are two ways you can download the System.Data.OleDb DLL.
MSI Installer: Download Microsoft.ACE.OLEDB.12.0 provider for 32bit and 64bit.
Nuget: Install System.Data.OleDb Nuget Package.
 
 

Connection Strings in AppSettings.json file

The connection string to the Database and Excel file are saved in the AppSettings.json file.
Note: For more details about saving and reading connection strings in AppSettings.json file, please refer .Net Core: Read Connection String from AppSettings.json file.
 
The DataSource property has been assigned a Placeholder {0}, which will be replaced by actual path of the File.
{
 "ConnectionStrings": {
    "Excel03ConString": "Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Extended Properties='Excel 8.0;HDR=YES'",
    "Excel07ConString": "Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Extended Properties='Excel 8.0;HDR=YES'"
 }
}
 
 

Namespaces

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

Model

The Model class consists of following properties.
public class CustomerModel
{
    ///<summary>
    /// Gets or sets CustomerId.
    ///</summary>
    public int CustomerId { get; set; }
 
    ///<summary>
    /// Gets or sets Name.
    ///</summary>
    public string Name { get; set; }
 
    ///<summary>
    /// Gets or sets Country.
    ///</summary>
    public string Country { get; set; }
}
 
 

Controller

The Controller consists of following Action methods.

Action method for handling GET operation

Inside this Action method, simple the View is returned.
 

Action method for handling POST operation for uploading and reading Excel file

This Action method gets called when the Import Button is clicked and it accepts IFormFile class as a parameter.
Note: The name of the IFormFile parameter and the name of HTML FileUpload element must be exact same, otherwise the IFormFile parameter will be NULL.
 
First a check is performed if the file is selected or not, if selected then the selected file is saved into a Folder (Directory) named Uploads using IWebHostEnvironment interface.
Note: For more details about IWebHostEnvironment interface, please refer my article Using IWebHostEnvironment in ASP.Net Core.
          For more details on how to access Static Files in Core, please refer my article Static Files (Images, CSS and JS files) in ASP.Net Core.
 
Then, using the switch case statement, the Excel file extension is determined and the connection string is built.
A connection is established with the Excel file using OLEDB classes and the name of the first sheet is determined and the first sheet data is read into a DataTable.
Finally, a FOR EACH loop is executed over the DataTable and the records are copied into the Generic List collection of CustomerModel class objects which is then sent to the View.
public class HomeController : Controller
{
    private IWebHostEnvironment Environment;
    private IConfiguration Configuration;
    public HomeController(IWebHostEnvironment _environment, IConfiguration _configuration)
    {
        this.Environment = _environment;
        this.Configuration = _configuration;
    }
 
    public IActionResult Index()
    {
        return View();
    }
 
    [HttpPost]
    public IActionResult Index(IFormFile postedFile)
    {
        List<CustomerModel> customers = new List<CustomerModel>();
        if (postedFile != null)
        {
            //Create a Folder.
            string path = Path.Combine(this.Environment.WebRootPath, "Uploads");
            if (!Directory.Exists(path))
            {
                Directory.CreateDirectory(path);
            }
 
            //Save the uploaded Excel file.
            string fileName = Path.GetFileName(postedFile.FileName);
            string filePath = Path.Combine(path, fileName);
            string extension = Path.GetExtension(postedFile.FileName);
            using (FileStream stream = new FileStream(filePath, FileMode.Create))
            {
                postedFile.CopyTo(stream);
            }
 
            //Read the connection string for the Excel file.
            string constr = string.Empty;
            switch (extension)
            {
                case ".xls": //Excel 97-03.
                    constr = this.Configuration.GetConnectionString("Excel03ConString");
                    break;
                case ".xlsx": //Excel 07 and above.
                    constr = this.Configuration.GetConnectionString("Excel07ConString");
                    break;
            }
 
            DataTable dt = new DataTable();
            constr = string.Format(constr, filePath);
 
            using (OleDbConnection connExcel = new OleDbConnection(constr))
            {
                using (OleDbCommand cmdExcel = new OleDbCommand())
                {
                    using (OleDbDataAdapter odaExcel = new OleDbDataAdapter())
                    {
                        cmdExcel.Connection = connExcel;
 
                        //Get the name of First Sheet.
                        connExcel.Open();
                        DataTable dtExcelSchema;
                        dtExcelSchema = connExcel.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
                        string sheetName = dtExcelSchema.Rows[0]["TABLE_NAME"].ToString();
                        connExcel.Close();
 
                        //Read Data from First Sheet.
                        connExcel.Open();
                        cmdExcel.CommandText = "SELECT * From [" + sheetName + "]";
                        odaExcel.SelectCommand = cmdExcel;
                        odaExcel.Fill(dt);
                        connExcel.Close();
 
                        foreach (DataRow row in dt.Rows)
                        {
                            customers.Add(new CustomerModel
                            {
                                CustomerId = Convert.ToInt32(row["Customer Id"]),
                                Name = row["Name"].ToString(),
                                Country = row["Country"].ToString()
                            });
                        }
                    }
                }
            }
        }
        return View(customers);
    }
}
 
 

View

HTML Markup

Inside the View, the Generic List collection of CustomerModel class is declared as Model for the Views.
The View consists of an HTML Form which has been created using the following TagHelpers attributes.
asp-action – Name of the Action. In this case the name is Index.
asp-controller – Name of the Controller. In this case the name is Home.
method – It specifies the Form Method i.e. GET or POST. In this case it will be set to POST.
HtmlAttributes – This array allows to specify the additional Form Attributes. Here we need to specify enctype = “multipart/form-data” which is necessary for uploading Files.
The View also consists of an HTML FileUpload element and a Submit Button.
 

Submitting the Form

For displaying the records, an HTML Table is used. A FOR loop will be executed over the Model which will generate the HTML Table rows with the Excel file data.
@using Read_Excel_OLEDB_Core.Models
@model List<CustomerModel>
@addTagHelper*, Microsoft.AspNetCore.Mvc.TagHelpers
@{
    Layout = null;
}
 
<!DOCTYPE html>
 
<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>Index</title>
</head>
<body>
    <form asp-controller="Home" asp-action="Index" method="post" enctype="multipart/form-data">
        <input type="file" name="postedFile" />
        <input type="submit" value="Import" />
    </form>
    <hr />
    @if (Model != null)
    {
        <table cellpadding="0" cellspacing="0">
            <tr>
                <th>Customer Id</th>
                <th>Name</th>
                <th>Country</th>
            </tr>
            @foreach (CustomerModel customer in Model)
            {
                <tr>
                    <td>@customer.CustomerId</td>
                    <td>@customer.Name</td>
                    <td>@customer.Country</td>
                </tr>
             }
        </table>
    }
</body>
</html>
 
 

Screenshots

The Excel File

ASP.Net Core: Upload, Read and Display Excel file data using OLEDB
 

Grid displaying Excel data

ASP.Net Core: Upload, Read and Display Excel file data using OLEDB
 
 

Downloads

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