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Attachments: Loading Attachments

Learn in this page how to load a part of an attachment, an entire attachment, or multiple attachments.

Load attachments​

  • Use these methods to load attachments from the 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.

  • Use this method to verify that an attachment exists.

    • session.Advanced.Attachments.Exists

Syntax​

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);

Example I​

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");
}

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.

// 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 part of an attachment​

Use GetRange to load a part of an attachment by document ID and the attachment name.

Syntax​

// Returns a range of the attachment by the document id and attachment name.
AttachmentResult GetRange(string documentId, string name, long? from, long? to);

// Returns a range of the attachment by the document id and attachment name.
AttachmentResult GetRange(object entity, string name, long? from, long? to);

Sample​

Album album = session.Load<Album>("albums/1");

AttachmentResult attachmentPart = session.Advanced.Attachments.GetRange(
                                          album, "track1.mp3", 101, 200);