officefileapi-devexpress-dot-spreadsheet-dot-workbook-dot-loaddocumentasync-x28-system-dot-string-system-dot-threading-dot-cancellationtoken-system-dot-iprogress-system-dot-int32-x29.md
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
Asynchronously loads a document from a file (the file format is determined based on document content). Allows you to implement progress notifications and cancel the operation.
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.v25.2.dll
NuGet Package : DevExpress.Document.Processor
public Task<bool> LoadDocumentAsync(
string fileName,
CancellationToken cancellationToken,
IProgress<int> progress
)
Public Function LoadDocumentAsync(
fileName As String,
cancellationToken As CancellationToken,
progress As IProgress(Of Integer)
) As Task(Of Boolean)
| Name | Type | Description |
|---|---|---|
| fileName | String |
The full path to the loaded file.
| | cancellationToken | CancellationToken |
A cancellation token that indicates whether to cancel the operation.
| | progress | IProgress<Int32> |
An object used to report the task progress in percentage. Use a Progress<T> class instance to report progress.
|
| Type | Description |
|---|---|
| Task<Boolean> |
A task that returns true if the document was loaded successfully; otherwise, false.
|
The Spreadsheet uses the built-in IFormatDetectorService service implementation to detect the loaded document format. If format detection fails, the Workbook.InvalidFormatException event fires.
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 example asynchronously loads and exports a workbook to PDF. The console window displays the progress of each operation. If the load or export operation takes longer than 30 seconds, it is canceled.
using System;
using System.Threading;
using System.Threading.Tasks;
using DevExpress.Spreadsheet;
// ...
static async Task Main(string[] args) {
var cancellationSource = new CancellationTokenSource(TimeSpan.FromSeconds(30));
var cancellationToken = cancellationSource.Token;
try {
using (Workbook workbook = new Workbook()) {
Console.WriteLine("Loading a document...");
await workbook.LoadDocumentAsync("Document.xlsx",
cancellationToken,
new Progress<int>((progress) => Console.WriteLine($"{progress}%")));
Console.WriteLine("Exporting to PDF...");
await workbook.ExportToPdfAsync("Result.pdf",
cancellationToken,
new Progress<int>((progress) => Console.WriteLine($"{progress}%")));
Console.WriteLine("Done!");
}
}
catch (OperationCanceledException) {
Console.WriteLine("Cancelled by timeout.");
}
finally {
cancellationSource.Dispose();
}
}
Imports System
Imports System.Threading
Imports System.Threading.Tasks
Imports DevExpress.Spreadsheet
Module Example
Sub Main()
MainAsync().Wait()
End Sub
Async Function MainAsync() As Task
Dim cancellationSource As New CancellationTokenSource(TimeSpan.FromSeconds(30))
Dim cancellationToken As CancellationToken = cancellationSource.Token
Try
Using workbook As New Workbook()
Console.WriteLine("Loading a document...")
Await workbook.LoadDocumentAsync("Document.xlsx", cancellationToken,
New Progress(Of Integer)(Sub(progress) Console.WriteLine($"{progress}%")))
Console.WriteLine("Exporting to PDF...")
Await workbook.ExportToPdfAsync("Result.pdf", cancellationToken,
New Progress(Of Integer)(Sub(progress) Console.WriteLine($"{progress}%")))
Console.WriteLine("Done!")
End Using
Catch e1 As OperationCanceledException
Console.WriteLine("Cancelled by timeout.")
Finally
cancellationSource.Dispose()
End Try
End Function
End Module
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.
using (Workbook workbook = new Workbook())
{
// Load a document.
// ...
// Calculate formulas in the document.
workbook.Calculate();
// ...
}
Using workbook As New Workbook()
' Load a document.
' ...
' Calculate formulas in the document.
workbook.Calculate()
' ...
End Using
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.
using (Workbook workbook = new Workbook())
{
// Change the calculation mode.
workbook.Options.CalculationMode = WorkbookCalculationMode.UseDocumentSettings;
// ...
// Load a document.
// ...
}
Using workbook As New Workbook()
' Change the calculation mode.
workbook.Options.CalculationMode = WorkbookCalculationMode.UseDocumentSettings
' ...
' Load a document.
' ...
End Using
The following code snippet (auto-collected from DevExpress Examples) contains a reference to the LoadDocumentAsync(String, CancellationToken, IProgress<Int32>) method.
Note
The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.
using (Workbook workbook = new Workbook()) {
await workbook.LoadDocumentAsync("Document.xlsx",
cancellationSource.Token,
Using workbook As Workbook = New Workbook()
Await workbook.LoadDocumentAsync("Document.xlsx", cancellationSource.Token, New Progress(Of Integer)(Sub(progress)
progressBarLoad.Value = progress
See Also