GetWritableDirectoryContents Method (IWritableDirectory)

Enumerate a directory at the given path, if any, and provide support for directory modifications.

Syntax

[NotNull()]
IWritableDirectoryContents GetWritableDirectoryContents( 
   string subpath
)

[NotNull()]
IWritableDirectoryContents^ GetWritableDirectoryContents( 
   String^ subpath
)

'Declaration
 
<NotNullAttribute()>
Function GetWritableDirectoryContents( _
   ByVal subpath As String _
) As IWritableDirectoryContents

'Usage
 
Dim instance As IWritableDirectory
Dim subpath As String
Dim value As IWritableDirectoryContents
 
value = instance.GetWritableDirectoryContents(subpath)

Parameters

subpath: Relative path that identifies the directory.
The value of this parameter can be null (Nothing in Visual Basic).

Return Value

Returns the writable contents of the directory.

This method never returns null (Nothing in Visual Basic).

Remarks

For Microsoft.Extensions.FileProviders.IDirectoryContents, IDirectory2, IDirectoryContents2, IWritableDirectory and IWritableDirectoryContents, relative paths are based on the directory itself; absolute paths are based on the root directory of the file provider. Notice the difference from Microsoft.Extensions.FileProviders.IFileInfo, IFileInfo2 and IWritableFileInfo, where relative paths are based on the directory where the file is located.

This method or property does not throw any exceptions, aside from execution exceptions such as System.Threading.ThreadAbortException or System.OutOfMemoryException.

Example

// Shows how to copy an OPC UA file, using the file provider model.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in C# on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-CSharp .
// Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
// a commercial license in order to use Online Forums, and we reply to every post.

using System;
using OpcLabs.BaseLib.Extensions.FileProviders;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.Extensions;
using OpcLabs.EasyOpc.UA.FileTransfer;

namespace UADocExamples.FileProviders._WritableFileInfo
{
    class CopyTo
    {
        public static void Main1()
        {
            // Unified Automation .NET based demo server (UaNETServer/UaServerNET.exe)
            var endpointDescriptor = new UAEndpointDescriptor("opc.tcp://localhost:48030")
                .WithUserNameIdentity("john", "master");

            // A node that represents an OPC UA file system (a root directory).
            UANodeDescriptor fileSystemNodeDescriptor = "nsu=http://www.unifiedautomation.com/DemoServer/ ;s=Demo.Files.FileSystem";

            // Create a random number generator - will be used for file/directory names.
            var random = new Random();

            // Instantiate the file transfer client object
            var fileTransferClient = new EasyUAFileTransferClient();

            Console.WriteLine("Getting writable file provider...");
            IWritableFileProvider writableFileProvider =
                fileTransferClient.GetWritableFileProvider(endpointDescriptor, fileSystemNodeDescriptor);
            // From this point onwards, the code is independent of the concrete realization of the file provider, and would
            // be identical e.g. for files in the physical file system, if the corresponding file provider was used.

            // Create a file, and a directory. Then, copy the file into the directory.
            try
            {
                string fileName = "MyFile-" + random.Next();
                Console.WriteLine($"Creating file, '{fileName}'...");
                IWritableFileInfo writableFileInfo = writableFileProvider.GetWritableFileInfo(fileName);
                writableFileInfo.WriteAllBytes(Array.Empty<byte>());

                string directoryName = "MyDirectory-" + random.Next();
                Console.WriteLine($"Creating directory, '{directoryName}'...");
                IWritableDirectoryContents writableDirectoryContents = writableFileProvider.GetWritableDirectoryContents(directoryName);
                writableDirectoryContents.Create();

                Console.WriteLine("Copying the file...");
                writableFileInfo.CopyTo(FormattableString.Invariant($"{directoryName}/{fileName}"));
            }
            // Methods in the file provider model throw IOException and other exceptions, but not UAException.
            catch (Exception exception)
            {
                Console.WriteLine($"*** Failure: {exception.GetBaseException().Message}");
                return;
            }

            Console.WriteLine("Finished...");
        }
    }
}

' Shows how to copy an OPC UA file, using the file provider model.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
' OPC client and subscriber examples in VB.NET on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VBNET .
' Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
' a commercial license in order to use Online Forums, and we reply to every post.

Imports OpcLabs.BaseLib.Extensions.FileProviders
Imports OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.Extensions
Imports OpcLabs.EasyOpc.UA.FileTransfer

Namespace FileProviders._WritableFileInfo

    Friend Class CopyTo

        Public Shared Sub Main1()

            ' Unified Automation .NET based demo server (UaNETServer/UaServerNET.exe)
            Dim endpointDescriptor As UAEndpointDescriptor =
                New UAEndpointDescriptor("opc.tcp://localhost:48030") _
                .WithUserNameIdentity("john", "master")

            ' A node that represents an OPC UA file system (a root directory).
            Dim fileSystemNodeDescriptor As UANodeDescriptor =
                "nsu=http://www.unifiedautomation.com/DemoServer/ ;s=Demo.Files.FileSystem"

            ' Create a random number generator - will be used for file/directory names.
            Dim random = New Random

            ' Instantiate the file transfer client object
            Dim fileTransferClient = New EasyUAFileTransferClient

            Console.WriteLine("Getting writable file provider...")
            Dim writableFileProvider As IWritableFileProvider =
                fileTransferClient.GetWritableFileProvider(endpointDescriptor, fileSystemNodeDescriptor)
            ' From this point onwards, the code is independent of the concrete realization of the file provider, and would
            ' be identical e.g. for files in the physical file system, if the corresponding file provider was used.

            ' Create a file, and a directory. Then, copy the file into the directory.
            Try
                Dim fileName As String = "MyFile-" & random.Next()
                Console.WriteLine($"Creating file, '{fileName}'...")
                Dim writableFileInfo As IWritableFileInfo = writableFileProvider.GetWritableFileInfo(fileName)
                writableFileInfo.WriteAllBytes(Array.Empty(Of Byte))

                Dim directoryName As String = "MyDirectory-" & random.Next()
                Console.WriteLine($"Creating directory, '{directoryName}'...")
                Dim writableDirectoryContents As IWritableDirectoryContents = writableFileProvider.GetWritableDirectoryContents(directoryName)
                writableDirectoryContents.Create()

                Console.WriteLine("Copying the file...")
                writableFileInfo.CopyTo(FormattableString.Invariant($"{directoryName}/{fileName}"))

                ' Methods in the file provider model throw IOException and other exceptions, but not UAException.
            Catch exception As Exception
                Console.WriteLine("*** Failure: {0}", exception.GetBaseException.Message)
                Exit Sub
            End Try

            Console.WriteLine("Finished...")
        End Sub
    End Class
End Namespace

# Shows how to copy an OPC UA file, using the file provider model.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
# OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python .
# Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
# a commercial license in order to use Online Forums, and we reply to every post.
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc
import random

# Import .NET namespaces.
from System import *
from OpcLabs.BaseLib.Extensions.FileProviders import *
from OpcLabs.EasyOpc.UA import *
from OpcLabs.EasyOpc.UA.Extensions import *
from OpcLabs.EasyOpc.UA.FileTransfer import *


# Unified Automation .NET based demo server (UaNETServer/UaServerNET.exe).
endpointDescriptor = UAEndpointDescriptor('opc.tcp://localhost:48030')
endpointDescriptor = UAEndpointDescriptorExtension.WithUserNameIdentity(endpointDescriptor,'john', 'master')

# A node that represents an OPC UA file system (a root directory).
fileSystemNodeDescriptor = UANodeDescriptor('nsu=http://www.unifiedautomation.com/DemoServer/ ;s=Demo.Files.FileSystem')

# Create a random number generator - will be used for file/directory names.
random = random.Random()

# Instantiate the file transfer client object.
fileTransferClient = EasyUAFileTransferClient()

# Prevent prompt to trust the server certificate (INSECURE, used just for smooth example flow).
EasyUAClient.SharedParameters.EngineParameters.CertificateAcceptancePolicy.TrustEndpointUrlString(
    endpointDescriptor.UrlString)

print('Getting writable file provider...')
writableFileProvider = IEasyUAFileTransferExtension.GetWritableFileProvider(fileTransferClient,
                                                                            endpointDescriptor,
                                                                            fileSystemNodeDescriptor)
# From this point onwards, the code is independent of the concrete realization of the file provider, and would
# be identical e.g. for files in the physical file system, if the corresponding file provider was used.

# Create a file, and a directory. Then, copy the file into the directory.
try:
    fileName = 'MyFile-' + str(random.randint(0, 999_999_999))
    print("Creating file, '", fileName, "'...", sep='')
    writableFileInfo = writableFileProvider.GetWritableFileInfo(fileName)
    IWritableFileInfoExtension.WriteAllBytes(writableFileInfo, Array.Empty[Byte]())

    directoryName = 'MyDirectory-' + str(random.randint(0, 999_999_999))
    print("Creating  directory, '", directoryName, "'...", sep='')
    writableDirectoryContents = writableFileProvider.GetWritableDirectoryContents(directoryName)
    writableDirectoryContents.Create()

    print('Copying the file...')
    IWritableFileInfoExtension.CopyTo(writableFileInfo, directoryName + '/' + fileName)

# Methods in the file provider model throw IOException and other exceptions, but not UAException.
except Exception as exception:
    print('*** Failure: ' + exception.GetBaseException().Message)
    exit()

print()
print('Finished.')

Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2016, Windows Server 2022; .NET: Linux, macOS, Microsoft Windows

Reference

IWritableDirectory Interface
IWritableDirectory Members

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