Loading and saving workbook in Blazor

8 Dec 20236 minutes to read

Opening an existing workbook from Stream

You can open an existing workbook from stream by using the overloads of Open methods of IWorkbooks interface.

The code snippet for this process in Blazor Server-Side application is given below.

//Creates a new instance for ExcelEngine
ExcelEngine excelEngine = new ExcelEngine();

//Initialize IApplication
IApplication application = excelEngine.Excel;

//Load the file into stream
FileStream inputStream = new FileStream("Sample.xlsx", FileMode.Open, FileAccess.Read);

//Loads or open an existing workbook through Open method of IWorkbooks
IWorkbook workbook = application.Workbooks.Open(inputStream);

The code snippet for this process in Blazor Client-Side application is given below.

//Creates a new instance for ExcelEngine
ExcelEngine excelEngine = new ExcelEngine();

//Initialize IApplication
IApplication application = excelEngine.Excel;

//Load the file into stream
Stream inputStream = await client.GetStreamAsync("sample-data/Sample.xlsx");

//Loads or open an existing workbook through Open method of IWorkbooks
IWorkbook workbook = application.Workbooks.Open(inputStream);

Saving an Excel workbook to stream

You can also save the created or manipulated workbook to stream using overloads of SaveAs methods.

The code snippet for this process in Blazor Server-Side application is given below.

//Creates a new instance for ExcelEngine
ExcelEngine excelEngine = new ExcelEngine();

//Initialize IApplication
IApplication application = excelEngine.Excel;

//Load the file into stream
FileStream inputStream = new FileStream("Sample.xlsx", FileMode.Open, FileAccess.Read);

//Loads or open an existing workbook through Open method of IWorkbooks
IWorkbook workbook = application.Workbooks.Open(inputStream);

//To-Do some manipulation
//To-Do some manipulation

//Set the version of the workbook
workbook.Version = ExcelVersion.Xlsx;

//Save the document as a stream and retrun the stream.
using (MemoryStream outputStream = new MemoryStream())
{
  //Save the created Excel document to MemoryStream.
  workbook.SaveAs(outputStream);

  return outputStream;
}

The code snippet for this process in Blazor Client-Side application is given below.

//Creates a new instance for ExcelEngine
ExcelEngine excelEngine = new ExcelEngine();

//Initialize IApplication
IApplication application = excelEngine.Excel;

//Load the file into stream
Stream inputStream = await client.GetStreamAsync("sample-data/Sample.xlsx");

//Loads or open an existing workbook through Open method of IWorkbooks
IWorkbook workbook = application.Workbooks.Open(inputStream);

//To-Do some manipulation
//To-Do some manipulation

//Set the version of the workbook
workbook.Version = ExcelVersion.Xlsx;

//Save the document as a stream and retrun the stream.
using (MemoryStream outputStream = new MemoryStream())
{
  //Save the created Excel document to MemoryStream.
  workbook.SaveAs(outputStream);

  return outputStream;
}

Helper Code Snippets

Create a class file with name as FileUtils and add the following code to invoke the JavaScript action for downloading the file in browser.

public static class FileUtils
{
    public static ValueTask<object> SaveAs(this IJSRuntime js, string filename, byte[] data)
        => js.InvokeAsync<object>(
           "saveAsFile",
           filename,
           Convert.ToBase64String(data));
}

Add the following JavaScript function in the index.html file present under wwwroot.

<script type="text/javascript">
  function saveAsFile(filename, bytesBase64) {

  if (navigator.msSaveBlob) 
  {
    //Download document in Edge browser
    var data = window.atob(bytesBase64);
    var bytes = new Uint8Array(data.length);
    for (var i = 0; i < data.length; i++) 
    {
      bytes[i] = data.charCodeAt(i);
    }
    var blob = new Blob([bytes.buffer], { type: "application/octet-stream" });
    navigator.msSaveBlob(blob, filename);
  }
  else 
  {
    var link = document.createElement('a');
    link.download = filename;
    link.href = "data:application/octet-stream;base64," + bytesBase64;
    document.body.appendChild(link); // Needed for Firefox
    link.click();
    document.body.removeChild(link);
  }
}
</script>

Add the following code under NavMenu.razor file present under Shared folder.

<li class="nav-item px-3">
  <NavLink class="nav-link" href="Excel">
    <span class="oi oi-list-rich" aria-hidden="true"></span> Create Excel
  </NavLink>
</li>

Add the service to services collection in ConfigureServices method of Startup.cs file.

services.AddSingleton<ExcelService>();