How to download/upload files from/to SharePoint 2013 using CSOM?

Question

I am developing a Win8 (WinRT, C#, XAML) client application (CSOM) that needs to download/upload files from/to SharePoint 2013.

How do I do the Download/Upload?

Answer 1

Though this is an old post and have many answers, but here I have my version of code to upload the file to sharepoint 2013 using CSOM(c#)

I hope if you are working with downloading and uploading files then you know how to create Clientcontext object and Web object

/* Assuming you have created ClientContext object and Web object*/
string listTitle = "List title where you want your file to upload";
string filePath = "your file physical path";
List oList = web.Lists.GetByTitle(listTitle);
clientContext.Load(oList.RootFolder);//to load the folder where you will upload the file
FileCreationInformation fileInfo = new FileCreationInformation();

fileInfo.Overwrite = true;
fileInfo.Content = System.IO.File.ReadAllBytes(filePath);
fileInfo.Url = fileName;

File fileToUpload = fileCollection.Add(fileInfo);
clientContext.ExecuteQuery();

fileToUpload.CheckIn("your checkin comment", CheckinType.MajorCheckIn);
if (oList.EnableMinorVersions)
{
    fileToUpload.Publish("your publish comment");
    clientContext.ExecuteQuery();
}
if (oList.EnableModeration)
{
     fileToUpload.Approve("your approve comment"); 
}
clientContext.ExecuteQuery();

And here is the code for download

List oList = web.Lists.GetByTitle("ListNameWhereFileExist");
clientContext.Load(oList);
clientContext.Load(oList.RootFolder);
clientContext.Load(oList.RootFolder.Files);
clientContext.ExecuteQuery();
FileCollection fileCollection = oList.RootFolder.Files;
File SP_file = fileCollection.GetByUrl("fileNameToDownloadWithExtension");
clientContext.Load(SP_file);
clientContext.ExecuteQuery();                
var Local_stream = System.IO.File.Open("c:/testing/" + SP_file.Name, System.IO.FileMode.CreateNew);
var fileInformation = File.OpenBinaryDirect(clientContext, SP_file.ServerRelativeUrl);
var Sp_Stream = fileInformation.Stream;
Sp_Stream.CopyTo(Local_stream);

Still there are different ways I believe that can be used to upload and download.