Workbook.LoadDocumentAsync(String) Method

SECURITY NOTE

Downloading documents passed into the LoadDocument method may create security issues. Review the following help topic and learn how to spot, analyze, and prohibit unwanted download requests:

Suppress Control Requests to Download Data from External URLs

Loads a document asynchronously from a file.

You need a license for the DevExpress Office File API Subscription or DevExpress Universal Subscription to use this method in production code.

Namespace: DevExpress.Spreadsheet

Assembly: DevExpress.Docs.v23.2.dll

NuGet Package: DevExpress.Document.Processor

Declaration

C#

public Task<bool> LoadDocumentAsync(
    string fileName
)

VB.NET

Public Function LoadDocumentAsync(
    fileName As String
) As Task(Of Boolean)

Parameters

Name	Type	Description
fileName	String	A string that specifies a file to load (including the full path).

Returns

Type	Description
Task<Boolean>	A Task<TResult> object that return true if the document was loaded successfully; otherwise, false.

Remarks

When you use this method to load a document from a file, the Spreadsheet automatically identifies the document’s format based on its content (regardless of filename extension).

If the format detection fails, the Workbook.InvalidFormatException event fires. To throw an exception when an invalid document is loaded, set the WorkbookImportOptions.ThrowExceptionOnInvalidDocument property to true (use the Workbook.Options.Import notation to access import options).

Handle the Workbook.DocumentLoaded event to determine when you can safely modify the loaded document.

Important

Take into account the following when you call this method:

• The events fired by this method call may occur in a different thread than the target operation.

• The operation is not thread safe (the document should not be accessed simultaneously by different threads). Wait until the operation is completed before you continue to work with the document (for example, use the await operator).

The following code sample shows how to merge two workbooks and save the result asynchronously.

C#

private async void MergeWorkbooks()
{
  using (Workbook workbook1 = new Workbook())
  using (Workbook workbook2 = new Workbook())
  {
      await Task.WhenAll(new Task[]
      {
          workbook1.LoadDocumentAsync("book1.xlsx"),
          workbook2.LoadDocumentAsync("book2.xlsx")
      });
      workbook1.Append(workbook2);
      await workbook1.SaveDocumentAsync("merged.xlsx");
  }
}

VB.NET

Private Async Sub MergeWorkbooks()
    Using workbook1 As Workbook = New Workbook()

        Using workbook2 As Workbook = New Workbook()
            Await Task.WhenAll(New Task() {workbook1.LoadDocumentAsync("book1.xlsx"), workbook2.LoadDocumentAsync("book2.xlsx")})
            workbook1.Append(workbook2)
            Await workbook1.SaveDocumentAsync("merged.xlsx")
        End Using
    End Using
End Sub

Calculate Formulas in the Loaded Document

The default calculation mode for a Workbook is Manual. This mode implies that the Spreadsheet does not recalculate formulas when you load a document. Call the Workbook.Calculate or Workbook.CalculateFull method to recalculate all formulas in the workbook.

C#

using (Workbook workbook = new Workbook())
{
    // Load a document.
    // ...
    // Calculate formulas in the document.
    workbook.Calculate();
    // ...
}

VB.NET

Using workbook As New Workbook()
    ' Load a document.
  ' ...
    ' Calculate formulas in the document.
    workbook.Calculate()
    ' ...
End Using

Change Calculation Mode

Use the Workbook.Options.CalculationMode property to change the calculation mode for a Workbook.

The following calculation modes are available:

• Manual (default) - Formulas are calculated only on demand (after the Calculate method call). It allows you to improve document generation speed for large workbooks with multiple formulas.

• UseDocumentSettings - Uses the calculation mode specified in the loaded document (this value is stored in the Workbook.DocumentSettings.Calculation.Mode property).

• Automatic - Recalculates formulas each time a cell value, formula, or defined name changes.

C#

using (Workbook workbook = new Workbook())
{
    // Change the calculation mode.
    workbook.Options.CalculationMode = WorkbookCalculationMode.UseDocumentSettings;
    // ...
    // Load a document.
    // ...
}

VB.NET

Using workbook As New Workbook()
  ' Change the calculation mode.
  workbook.Options.CalculationMode = WorkbookCalculationMode.UseDocumentSettings
  ' ...
  ' Load a document.
  ' ...
End Using