WorkbookBase.ProtectDocument Method

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Called by the Visual Studio Tools for Office runtime so that you can reapply password protection to the workbook after the cached data has been saved.

Namespace:  Microsoft.Office.Tools.Excel
Assembly:  Microsoft.Office.Tools.Excel.v4.0.Utilities (in Microsoft.Office.Tools.Excel.v4.0.Utilities.dll)

Syntax

'Declaration
Protected Overridable Sub ProtectDocument

protected virtual void ProtectDocument()

Remarks

Override this method in a document-level project for Excel if your workbook is protected by using a password, and it contains cached data that might be changed at run time. In your implementation of this method, use the Protect method to protect the workbook.

By default, changes to cached data in a password-protected workbook are not persisted when the workbook is saved. To save changes to the cached data, you must override the following methods in your project:

  • UnprotectDocument. When the workbook is saved, the Visual Studio Tools for Office runtime calls this method. Add code to this method that temporarily unprotects the workbook. This enables changes to the cached data to be saved.

  • ProtectDocument. After the workbook is saved, the Visual Studio Tools for Office runtime calls this method. Add code to this method that reapplies protection to the workbook.

For more information, see How to: Cache Data in a Password-Protected Document.

The Visual Studio Tools for Office runtime calls the ProtectDocument method even if the cached data could not be saved because of some error that is unrelated to the password protection. For example, if you implement the ICachedType interface to customize how cached data is stored in the document, the ProtectDocument method is called even if your ICachedType implementation throws an exception that prevents the cached data from being saved.

Examples

The following code example demonstrates how to override the ProtectDocument method to reapply protection that was removed by overriding the UnprotectDocument method. To use this code, run it from the ThisWorkbook class in a document-level project for Excel. The code assumes that the password is stored in a field named securelyStoredPassword.

<CachedAttribute()> _
Public CachedString As String = "This string is cached in the workbook."

Private protectStructureValue As Boolean
Private protectWindowsValue As Boolean

Protected Overrides Sub UnprotectDocument()
    protectStructureValue = Me.ProtectStructure
    protectWindowsValue = Me.ProtectWindows

    Me.Unprotect(securelyStoredPassword)
End Sub

Protected Overrides Sub ProtectDocument()
    Me.Protect(securelyStoredPassword, protectStructureValue, _
        protectWindowsValue)
End Sub

[CachedAttribute]
public string CachedString = "This string is cached in the workbook.";

private bool protectStructureValue;
private bool protectWindowsValue;

protected override void UnprotectDocument()
{
    protectStructureValue = this.ProtectStructure;
    protectWindowsValue = this.ProtectWindows;

    this.Unprotect(securelyStoredPassword);
}

protected override void ProtectDocument()
{
    this.Protect(securelyStoredPassword, protectStructureValue,
        protectWindowsValue);
}

.NET Framework Security

See Also

Reference

WorkbookBase Class

Microsoft.Office.Tools.Excel Namespace

UnprotectDocument

Other Resources

Caching Data

How to: Cache Data in a Password-Protected Document