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ApplicationDeployment::CheckForUpdateAsync Method

Checks UpdateLocation asynchronously to determine whether a new update is available.

Namespace:  System.Deployment.Application
Assembly:  System.Deployment (in System.Deployment.dll)

public:
void CheckForUpdateAsync()

ExceptionCondition
InvalidOperationException

ClickOnce throws this exception immediately if you call the CheckForUpdateAsync method while an update is already in progress.

DeploymentDownloadException

The deployment manifest cannot be downloaded. This exception appears in the Error property of the CheckForUpdateCompleted event.

InvalidDeploymentException

The deployment manifest is corrupted. You will likely need to redeploy the application to fix this problem. This exception appears in the Error property of the CheckForUpdateCompleted event.

CheckForUpdateAsync returns immediately and starts a separate thread for downloading the updated application. When the method completes or is canceled, it raises the CheckForUpdateCompleted event. You can use AsyncCompletedEventArgs in this event handler to determine whether the operation was canceled, or if an exception was raised during update.

You can cancel an asynchronous update by calling CheckForUpdateAsyncCancel.

NoteNote

 If CheckForUpdate discovers that an update is available, and the user chooses not to install it, ClickOnce will prompt the user that an update is available the next time the application is run. There is no way to disable this prompting. (If the application is a required update, ClickOnce will install it without prompting.)

The following example checks for an update asynchronously, and installs the update if one exists.


private:
    long sizeOfUpdate;


private:
    void Form1_Load(Object^ sender, System::EventArgs^ e)
    {
        DoUpdate();
    }

public:
    void DoUpdate()
    {
        if (ApplicationDeployment::IsNetworkDeployed)
        {
            ApplicationDeployment^ currentAppDeployment =
                ApplicationDeployment::CurrentDeployment;
            currentAppDeployment->CheckForUpdateCompleted +=
                gcnew CheckForUpdateCompletedEventHandler(
                this, &Form1::currentDeploy_CheckForUpdateCompleted);
            currentAppDeployment->CheckForUpdateAsync();
        }
    }

    // If update is available, fetch it.
    void currentDeploy_CheckForUpdateCompleted(Object^ sender,
        CheckForUpdateCompletedEventArgs^ e)
    {
        if (nullptr != e->Error)
        {
            // Log error.
            return;
        }

        if (e->UpdateAvailable)
        {
            sizeOfUpdate = (long) e->UpdateSizeBytes;
            if (!e->IsUpdateRequired)
            {
                System::Windows::Forms::DialogResult 
                    updateDialogueResult = MessageBox::Show(
                    "An update is available.Would you like to update the" +
                    " application now?", "Update Available",
                    MessageBoxButtons::OKCancel);
                if (System::Windows::Forms::DialogResult::OK == 
                    updateDialogueResult)
                {
                    BeginUpdate();
                }
            }
            else
            {
                BeginUpdate();
            }
        }
    }

    void BeginUpdate()
    {
        ApplicationDeployment^ ad = ApplicationDeployment::CurrentDeployment;
        ad->UpdateCompleted +=
            gcnew AsyncCompletedEventHandler(
            this, &Form1::CurrentDeployment_UpdateCompleted);

        // Indicate progress in the application's status bar.
        ad->UpdateProgressChanged +=
            gcnew DeploymentProgressChangedEventHandler(this, 
            &Form1::ad_ProgressChanged);

        ad->UpdateAsync();
    }

    void CurrentDeployment_UpdateCompleted(Object^ sender,
        AsyncCompletedEventArgs^ e)
    {
        if (!e->Cancelled)
        {
            if (nullptr != e->Error)
            {
                System::Windows::Forms::DialogResult 
                    restartDialogueResult = MessageBox::Show(
                    "The application has been updated. Restart?",
                    "Restart Application",
                    MessageBoxButtons::OKCancel);
                if (System::Windows::Forms::DialogResult::OK == 
                    restartDialogueResult)
                {
                    Application::Restart();
                }
            }
            else
            {
                // Replace with your own error reporting or logging.
                MessageBox::Show(
                    "The application encountered an error in downloading" +
                    " the latest update. Error: {0}",
                    e->Error->Message);
            }
        }
        else
        {
            // Replace with your own error reporting or logging.
            MessageBox::Show("The update of the application's latest" +
                " version was cancelled.");
        }
    }

    void ad_ProgressChanged(Object^ sender,
        DeploymentProgressChangedEventArgs^ e)
    {
        String^ progressText =
            String::Format(
            "{0:D}K out of {1:D}K downloaded - {2:D}% complete",
            e->BytesCompleted / 1024, e->BytesTotal / 1024,
            e->ProgressPercentage);
        statusStrip1->Text = progressText;
    }


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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