Attachments: Loading Attachments

There are a few methods that allow you to download attachments from a database:

session.Advanced.Attachments.Get can be used to download an attachment or multiple attachments.
session.Advanced.Attachments.GetNames can be used to download all attachment names that are attached to a document.
session.Advanced.Attachments.GetRevision can be used to download an attachment of a revision document.
session.Advanced.Attachments.Exists can be used to determine if an attachment exists on a document.

Syntax

• Sync
• Async

AttachmentResult Get(string documentId, string name);
AttachmentResult Get(object entity, string name);
IEnumerator<AttachmentEnumeratorResult> Get(IEnumerable<AttachmentRequest> attachments);
AttachmentName[] GetNames(object entity);
AttachmentResult GetRevision(string documentId, string name, string changeVector);
bool Exists(string documentId, string name);

Task<AttachmentResult> GetAsync(string documentId, string name, CancellationToken token = default);
Task<AttachmentResult> GetAsync(object entity, string name, CancellationToken token = default);
Task<IEnumerator<AttachmentEnumeratorResult>> GetAsync(IEnumerable<AttachmentRequest> attachments, CancellationToken token = default);
Task<AttachmentResult> GetRevisionAsync(string documentId, string name, string changeVector, CancellationToken token = default);
Task<bool> ExistsAsync(string documentId, string name, CancellationToken token = default);

Example I

• Sync
• Async

using (var session = store.OpenSession())
{
  Album album = session.Load<Album>("albums/1");

  using (AttachmentResult file1 = session.Advanced.Attachments.Get(album, "001.jpg"))
  using (AttachmentResult file2 = session.Advanced.Attachments.Get("albums/1", "002.jpg"))
  {
      Stream stream = file1.Stream;

      AttachmentDetails attachmentDetails = file1.Details;
      string name = attachmentDetails.Name;
      string contentType = attachmentDetails.ContentType;
      string hash = attachmentDetails.Hash;
      long size = attachmentDetails.Size;
      string documentId = attachmentDetails.DocumentId;
      string changeVector = attachmentDetails.ChangeVector;
  }

  AttachmentName[] attachmentNames = session.Advanced.Attachments.GetNames(album);
  foreach (AttachmentName attachmentName in attachmentNames)
  {
      string name = attachmentName.Name;
      string contentType = attachmentName.ContentType;
      string hash = attachmentName.Hash;
      long size = attachmentName.Size;
  }

  bool exists = session.Advanced.Attachments.Exists("albums/1", "003.jpg");
}

using (var asyncSession = store.OpenAsyncSession())
{
  Album album = await asyncSession.LoadAsync<Album>("albums/1");

  using (AttachmentResult file1 = await asyncSession.Advanced.Attachments.GetAsync(album, "001.jpg"))
  using (AttachmentResult file2 = await asyncSession.Advanced.Attachments.GetAsync("albums/1", "002.jpg"))
  {
      Stream stream = file1.Stream;

      AttachmentDetails attachmentDetails = file1.Details;
      string name = attachmentDetails.Name;
      string contentType = attachmentDetails.ContentType;
      string hash = attachmentDetails.Hash;
      long size = attachmentDetails.Size;
      string documentId = attachmentDetails.DocumentId;
      string changeVector = attachmentDetails.ChangeVector;
  }

  AttachmentName[] attachmentNames = asyncSession.Advanced.Attachments.GetNames(album);
  foreach (AttachmentName attachmentName in attachmentNames)
  {
      string name = attachmentName.Name;
      string contentType = attachmentName.ContentType;
      string hash = attachmentName.Hash;
      long size = attachmentName.Size;
  }

  bool exists = await asyncSession.Advanced.Attachments.ExistsAsync("albums/1", "003.jpg");
}

Example II

Here, we load multiple string attachments we previously created for a document. We then go through them, and decode each attachment to its original text.

• Sync
• Async

// Load a user profile
var user = session.Load<User>(userId);

// Get the names of files attached to this document
IEnumerable<AttachmentRequest> attachmentNames = session.Advanced.Attachments.GetNames(user).Select(x => new AttachmentRequest(userId, x.Name));

// Get the attached files
IEnumerator<AttachmentEnumeratorResult> attachmentsEnumerator = session.Advanced.Attachments.Get(attachmentNames);

// Go through the document's attachments
while (attachmentsEnumerator.MoveNext())
{
  AttachmentEnumeratorResult res = attachmentsEnumerator.Current;

  AttachmentDetails attachmentDetails = res.Details; // attachment details

  Stream attachmentStream = res.Stream; // attachment contents

  // In this case it is a string attachment, that can be decoded back to text 
  var ms = new MemoryStream();
  attachmentStream.CopyTo(ms);
  string decodedStream = Encoding.UTF8.GetString(ms.ToArray());
}

// Load a user profile
var user = await session.LoadAsync<User>(userId);

// Get the names of files attached to this document
IEnumerable<AttachmentRequest> attachmentNames = session.Advanced.Attachments.GetNames(user).Select(x => new AttachmentRequest(userId, x.Name));

// Get the attached files
IEnumerator<AttachmentEnumeratorResult> attachmentsEnumerator = await session.Advanced.Attachments.GetAsync(attachmentNames);

// Go through the document's attachments
while (attachmentsEnumerator.MoveNext())
{
  AttachmentEnumeratorResult res = attachmentsEnumerator.Current;

  AttachmentDetails attachmentDetails = res.Details; // attachment details

  Stream attachmentStream = res.Stream; // attachment contents

  // In this case it is a string attachment, that can be decoded back to text 
  var ms = new MemoryStream();
  attachmentStream.CopyTo(ms);
  string decodedStream = Encoding.UTF8.GetString(ms.ToArray());
}