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SaveAttachmentToCache Method

Summary

Saves an attachment to the cache.

Syntax
C#
C++/CLI
Python
public static string SaveAttachmentToCache( 
   LoadFromCacheOptions loadOptions, 
   SaveAttachmentToCacheOptions saveOptions 
) 
public:  
   static String^ SaveAttachmentToCache( 
      LoadFromCacheOptions^ loadOptions, 
      SaveAttachmentToCacheOptions^ saveOptions 
   ) 
def SaveAttachmentToCache(self,saveOptions): 

Parameters

loadOptions

Options to identify the owner document. This value cannot be null.

saveOptions

Options to identify and save the attachment. This value cannot be null.

Return Value

The ID of the attachment document saved into the cache if successful; otherwise, null.

Remarks

Use LEADDocument.SaveAttachmentToCache to save an attachment if the owner document is already loaded as a LEADDocument object. The remarks on this section regarding loadOptions is not used since the owner document is already loaded. However, the remarks regarding saveOptions applies.

Use DocumentFactory.SaveAttachmentToCache to save an attachment if the owner document is not loaded and only its ID is available.

This method works as follows:

  1. The owner document is loaded from the cache using the options set in loadOptions using LoadFromCache. If not successful, null is returned.

  2. The corresponding DocumentAttachment object for SaveAttachmentToCacheOptions.AttachmentNumber of saveOptions is obtained.

If not successful, an exception is thrown.

  1. If the value of DocumentAttachment.DocumentId is not null, it is assumed that the attachment document is already is in the cache and therefore this value is returned directly.

If this value is null or checking if the document in cache fails, then the workflow continues to the next section.

  1. If the attachment is not embedded (the value of DocumentAttachment.IsEmbedded is false), then null is returned.

  2. If the attachment is embedded (the value of DocumentAttachment.IsEmbedded is true), then the attachment data is obtained through DocumentAttachments.CreateAttachmentStream; and if successful, saved (uploaded) into the cache using the options set in SaveAttachmentToCacheOptions.UploadDocumentOptions of saveOptions. The ID of this new document is returned.

For more information, refer to Document Attachments.

Example
C#
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Document.Writer; 
 
using Leadtools.Document; 
using Leadtools.Caching; 
using Leadtools.Annotations.Engine; 
using Leadtools.Ocr; 
using Leadtools.Barcode; 
using Leadtools.Document.Converter; 
 
public void AttachmentsExample() 
{ 
   // The PDF document can be one of the following: 
   // 1. Normal PDF without attachments. Has one or more pages and no attachments. 
   // 2. Normal PDF with attachments. Has one or more pages and one or more attachments. 
   // 3. PDF Portfolio. Has a placeholder page and one or more attachments. 
 
   // The value of LoadDocumentOptions.LoadAttachmentsMode affects loading the documents as follows: 
 
   // 1. Normal PDF without attachments: Will not be affected. 
   // 2. Normal PDF with attachments: Number of pages is not affected. 
   //    Number of attachments is: 
   //       LoadAttachmentsMode = None then 0 
   //       LoadAttachmentsMode = AsAttachments then number of attachments found in the document. 
   // 3. PDF Portfolio: Number of pages is: 
   //       LoadAttachmentsMode = None then 1 (the placeholder page) 
   //       LoadAttachmentsMode = AsAttachments then 0 (the document has no pages). 
   //    Number of attachments is: 
   //       LoadAttachmentsMode = None then 0 
   //       LoadAttachmentsMode = AsAttachments then number of attachments found in the document. 
 
   // First, load the document without attachments 
   string pdfFile = Path.Combine(LEAD_VARS.ImagesDir, "Leadtools.pdf"); 
   string outputDirectory = Path.GetDirectoryName(LEAD_VARS.ImagesDir); 
 
   Console.WriteLine($"Loading with DocumentLoadAttachmentsMode.None"); 
   var loadDocumentOptions = new LoadDocumentOptions(); 
   loadDocumentOptions.LoadAttachmentsMode = DocumentLoadAttachmentsMode.None; 
   using (LEADDocument document = DocumentFactory.LoadFromFile(pdfFile, loadDocumentOptions)) 
   { 
      Console.WriteLine(document.GetDocumentFileName()); 
      Console.WriteLine($"Document has {document.Pages.Count} pages"); 
 
      // Find out if the document is portfolio 
      bool isPortfolio = 
         document.Metadata.ContainsKey(LEADDocument.MetadataKey_IsPortfolio) && 
         bool.Parse(document.Metadata[LEADDocument.MetadataKey_IsPortfolio]); 
      Console.WriteLine($"IsPortfolio:{isPortfolio}"); 
 
      // Check that everything is as expected 
 
      // We should have 0 attachments since we did not instruct the toolkit to load these 
      Debug.Assert(document.Attachments.Count == 0); 
 
      // We should have one or more pages regardless of whether the document is PDF portfolio 
      Debug.Assert(document.Pages.Count > 0); 
   } 
 
   // Next, load the document with attachments 
   Console.WriteLine($"Loading with DocumentLoadAttachmentsMode.AsAttachments"); 
   loadDocumentOptions.LoadAttachmentsMode = DocumentLoadAttachmentsMode.AsAttachments; 
   using (LEADDocument document = DocumentFactory.LoadFromFile(pdfFile, loadDocumentOptions)) 
   { 
      document.AutoDeleteAttachmentsFromCache = true; 
             
      Console.WriteLine($"Document has {document.Pages.Count} pages"); 
 
      // Find out if the document is portfolio 
      bool isPortfolio = 
         document.Metadata.ContainsKey(LEADDocument.MetadataKey_IsPortfolio) && 
         bool.Parse(document.Metadata[LEADDocument.MetadataKey_IsPortfolio]); 
      Console.WriteLine($"IsPortfolio:{isPortfolio}"); 
 
      // Check that everything is as expected 
 
      // We may have 0 or more attachments depending on the file 
      Console.WriteLine($"Document has {document.Attachments.Count} attachments"); 
 
      // We should have one or more pages unless this is PDF portfolio, then it will have 0 pages 
      if (isPortfolio) 
      { 
         Debug.Assert(document.Pages.Count == 0); 
      } 
 
      // Extract all the attachments into the output directory 
      foreach (DocumentAttachment attachment in document.Attachments) 
      { 
         // Show info on this attachment 
         Console.WriteLine($"Attachment number {attachment.AttachmentNumber} file name is '{attachment.FileName}', " + 
            $"length is {attachment.FileLength} bytes, and ID is {attachment.DocumentId}, Is Embedded: {attachment.IsEmbedded}"); 
         // Get the attachment file name 
         // This value may not be unique, so combine it with the attachment number 
         string attachmentFileName = $"{attachment.AttachmentNumber}-{attachment.FileName}"; 
         attachmentFileName = Path.Combine(outputDirectory, attachmentFileName); 
 
         // Get the attachment as a stream, we do not want to save it to the cache so pass null for that 
         // DocumentAttachments reference 
         using (Stream attachmentStream = document.Attachments.CreateAttachmentStream(attachment.AttachmentNumber, null)) 
         { 
            if (attachmentStream != null) 
            { 
               // Save it to the output file 
               using (var stream = File.Create(attachmentFileName)) 
               { 
                  document.SaveAttachmentToCache(null); 
                  attachmentStream.CopyTo(stream); 
               } 
            } 
         } 
 
         var saveOptions = new SaveAttachmentToCacheOptions(); 
         saveOptions.AttachmentNumber = 0; 
         saveOptions.UpdateAttachmentDocumentId = true; 
         saveOptions.UploadDocumentOptions = new UploadDocumentOptions(); 
         document.SaveAttachmentToCache(saveOptions); 
 
         // Or load this attachment as a LEADDocument, this might fail if the attachment is not of a valid image 
         // or document format 
         try 
         { 
            Console.WriteLine("Loading as LEADDocument"); 
            var loadAttachmentOptions = new LoadAttachmentOptions(); 
            loadAttachmentOptions.AttachmentNumber = attachment.AttachmentNumber; 
            loadAttachmentOptions.UpdateAttachmentDocumentId = true; 
            using (LEADDocument attachmentDocument = document.LoadDocumentAttachment(loadAttachmentOptions)) 
            { 
               Console.WriteLine($"Success, attachment document mime type is {attachmentDocument.MimeType} and has {attachmentDocument.Pages.Count} pages"); 
            } 
         } 
         catch (Exception ex) 
         { 
            Console.WriteLine($"Error {ex.Message}"); 
         } 
      } 
   } 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images"; 
} 
Requirements

Target Platforms

Help Version 22.0.2023.4.21
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© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.

Leadtools.Document Assembly

Products | Support | Contact Us | Intellectual Property Notices
© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.