Download file from sharepoint directly when you have only file name but dont have the sourcedoc

Question

Code:

using (ClientContext clientContext = new PnP.Framework.AuthenticationManager().GetACSAppOnlyContext(siteUrl, clientID, clientSecret)) 
{
    Web web = clientContext.Web;
    fileUrl = downloadUrl + fileUrl + ".pptx";
    Microsoft.SharePoint.Client.File filetoDownload = web.GetFileByUrl(fileUrl);

    clientContext.Load(filetoDownload);
    clientContext.ExecuteQuery();

    Helper.CreateIfMissing(filePath);

    var stream = filetoDownload.OpenBinaryStream();
    clientContext.ExecuteQuery();

    var fileName = Path.Combine(filePath, (string)filetoDownload.Name);

    // Add in Config for downloadload
    using (var fileStream = new FileStream(fileName, FileMode.Create))
    {
        stream.Value.CopyTo(fileStream);
    }

    path = fileName;
 }

Config:

"downloadUrl": "https://abc.sharepoint.com/:p:/r/sites/abcFolder/_layouts/15/Doc.aspx?sourcedoc=%7BA6BACCWE-E545-4823-A765-749100023273%7D&file="

I want to download the file and have 2 approaches in mind:

1. Since every file in the SharePoint folder will have its own source doc. Can I get the sourcedoc from the filename which user pass as an input?
2. Can we download file without this sourcedoc only with the help of filename?

SharePoint folder structure:

www.abcsite.com/MainFolder/SubFolder/FileName

FileFormat: .pptx

Answer 1

An easy way to get a document is to build a REST API url. To download a document stored in a document library, you can use this URL with a GET method ($value at the end is important!):

https://abc.sharepoint.com/sites/abcFolder/_api/web/GetFileByServerRelativeUrl('/sites/abcFolder/abcLibrary/MainFolder/SubFolder/FileName.pptx')/$value

If you test this URL in a web browser, the filename will be $value but with your C# code you can rename the downloaded content to something like FileName.pptx.

So, yes, you can download files based on their name if you know in which site/library/folder they are stored. Do not use Doc.aspx?sourcedoc.

Answer 2

There is an easy to get this done with the same code. Just make your url like this in app config old download url: "downloadUrl": "https://abc.sharepoint.com/:p:/r/sites/abcFolder/_layouts/15/Doc.aspx?sourcedoc=%7BA6BACCWE-E545-4823-A765-749100023273%7D&file="

new url "downloadUrl": "https://abc.sharepoint.com/MainFolder/Subfolder/FileName

In c# code attach the file name to this url with file extension and pass it to the same getfilebyUrl method fileurl=downloadurl+filename+".pptx"