directly download file from DB

Question

Hi All,
I need to download from DB a PDF tha is stores as Base64 format
I would like to do that directly in SAIL to allow to our users to dwnload directly from the interface this document
How can I do that , is there a method ?
Thanks
Elia

Eliot Gerson · Accepted Answer

I would recommend against that sort of approach, as it could lead to performance issues. Instead, simply upload the file as a document in Appian, and use the a!documentDownloadLink() SAIL component docs.appian.com/.../Document_Link_Component.html to allow users to download it.

Shyam Bommakanti · Answer

The closest I found is a smartservice to retrieve documents stored as base64 string from DB is this component: forum.appian.com/.../summary 
 
You can customize it to return a document via expression similar to how downloaddatasubset works. 
 
I agree with Eliot, use Appian collaboration for better performance and to follow best practice.

aloks0189 · Answer

eliav do you really want to store the documents into the DB and retrieve the same from DB, because it takes a lot of time to store as well as to retrieve the document and this impact the performance too, so as you are saying that you want to retrieve the Document from DB on SAIL, so will your customer really be happy if your UI takes huge time to load, because i don&#x27;t think so. However if you want the same the you can create a Custom Plugin to do that. or you can take the help of SmartService mention by Shyam Bommakanti

rawich · Answer

eliav If the SAIL screen is a UI of User Input Task, and the user will most likely need to download the document, then using the Smart Service suggested by Shyam Bommakanti make the most sense. You can use the Smart Service to retrieve the document from DB into Appian document, then provide the link in SAIL UI. You should perform clean up work of deleting the Appian document, after the task or when the process is about to complete. 
 
If your use case is different, another approach is to create a link using another web application or custom Appian Servlet plug-in. Create the web application or Servlet in such a way that you can construct URL link from your SAIL UI to point to a specific document in the database. The document do not get retrieved or accessed in anyway until the end user actually click on the link to download. When the link is clicked, the web app or Servlet, retrieve the document for the user to download. There shouldn&#x27;t be performance concerns in this approach, as the documents are not retrieved from DB until the user actually click on the link to download.