Download a specific file from SharePoint (CSOM) using C#

Question

I'm developing a C# based application that requires to download, checkout, upload, check in on a specific file from/to Sharepoint with CSOM. So I have two questions here:

Firstly, on download, is there others way to download a specific named file under folder "Document" instead of searching through GetItemByID(). Please refer to code below:

string siteUrl = @"http://test.com/sites/company/";

ClientContext ctx = new ClientContext(siteUrl);
ctx.Credentials = new NetworkCredential("username", "password" , "domain");            
ctx.AuthenticationMode = ClientAuthenticationMode.Default;

var list = ctx.Web.Lists.GetByTitle("Document");
var listItem = list.GetItemById();

ctx.Load(list);
ctx.Load(listItem, i => i.File);
ctx.ExecuteQuery();

var fileRef = listItem.File.ServerRelativeUrl;
var fileInfo = Microsoft.SharePoint.Client.File.OpenBinaryDirect(ctx, fileRef);
var fileName = Path.Combine("C:\\", (string)listItem.File.Name);

using (var fileStream = System.IO.File.Create(fileName))
{
    fileInfo.Stream.CopyTo(fileStream);
}

Secondly, in regards to the workflow (download, modify, check out, upload, check in), is this feasible of doing?

Thanks in advance.

Answer 1

You could use caml query to filter based on file name.

var list = clientContext.Web.Lists.GetByTitle("DocSet");
                CamlQuery camlQuery = new CamlQuery();
                camlQuery.ViewXml = @"<View Scope='Recursive'>
                                         <Query>
                                           <Where><Eq><FieldRef Name='FileLeafRef'/><Value Type='File'>testdata.xlsx</Value></Eq></Where>
                                         </Query>                                        
                                     </View>";
                ListItemCollection listItems = list.GetItems(camlQuery);
                clientContext.Load(listItems);
                clientContext.ExecuteQuery();

Download file in workflow would be touch based on my knowledge, while you could create custom service host in SharePoint so you could call the service.