Provider Hosted App – Upload Large Files using CSOM

We all at some time struggled with uploading large files using CSOM in O365. Using managed client object model, we can upload a maximum of 2MB file size. If the file is of larger size, we usually had two options:

1. File.SaveBinaryDirect
2. Using REST which supports upto 2GB

The first option can not be used in Sharepoint Online because SaveBinaryDirect does not work with claims authentication (check this link).

Update: We can now use SaveBinaryDirect in SP Online by using SharePointOnlineCredentials class which could be used for authentication of context but I am yet not able to make it work in provider hosted add-in. It works in normal console app by providing credentials though.

Does that mean we are left with REST only? Actually NO. We have one more way by which we can upload files greater than 2MB in O365 using CSOM in provider hosted app. But let’s first see the standard CSOM way which allows us 2MB file upload.

	var spContext = SharePointContextProvider.Current.GetSharePointContext(HttpContext, SPHostUrl);
	using (var clientContext = spContext.CreateUserClientContextForSPAppWeb())
	{
	if (clientContext != null)
	{
	//code for file size < 2MB
	//file is the input which we uploaded. It can be taken from Request.Files
	FileCreationInformation newFile = new FileCreationInformation();
	newFile.Content = System.IO.File.ReadAllBytes(file.FileName);
	newFile.Url = Path.GetFileName(file.FileName);
	List docs = clientContext.Web.Lists.GetByTitle("List_Name");
	Microsoft.SharePoint.Client.File uploadFile = docs.RootFolder.Files.Add(newFile);
	clientContext.Load(uploadFile);
	clientContext.ExecuteQuery();
	}
	}

view raw

uploadfile.cs

hosted with ❤ by GitHub

Now the method to upload larger files is exactly the same. We only have to use FileCreationInformation.ContentStream property instead of FileCreationInformation.Content property. The whole code is present below:

	var spContext = SharePointContextProvider.Current.GetSharePointContext(HttpContext, SPHostUrl);
	using (var clientContext = spContext.CreateUserClientContextForSPAppWeb())
	{
	if (clientContext != null)
	{
	//file is uploaded file. Could be read from Request.Files
	using (FileStream fs = new FileStream(file.FileName, FileMode.Open))
	{
	//code for file size > 2MB. tested upto 50MB
	FileCreationInformation newFile = new FileCreationInformation();
	newFile.ContentStream = fs;
	newFile.Url = Path.GetFileName(file.FileName);
	newFile.Overwrite = true;
	List docs = clientContext.Web.Lists.GetByTitle("List_Name");
	Microsoft.SharePoint.Client.File uploadFile = docs.RootFolder.Files.Add(newFile);
	clientContext.Load(uploadFile);
	clientContext.ExecuteQuery();
	}
	}
	}

view raw

uploadfilelarge.cs

hosted with ❤ by GitHub

In some cases, you might get a FileNotFoundException while using above code. Below is another way to use the code

	var spContext = SharePointContextProvider.Current.GetSharePointContext(HttpContext, SPHostUrl);
	using (var clientContext = spContext.CreateUserClientContextForSPAppWeb())
	{
	if (clientContext != null)
	{
	FileCreationInformation newFile = new FileCreationInformation();
	//here file is the selected file. In this case of type HttpPostedFileBase
	newFile.ContentStream = file.InputStream;
	newFile.Url = Path.GetFileName(file.FileName);
	newFile.Overwrite = true;
	List docs = clientContext.Web.Lists.GetByTitle("List_Name");
	Microsoft.SharePoint.Client.File uploadFile = docs.RootFolder.Files.Add(newFile);
	clientContext.Load(uploadFile);
	clientContext.ExecuteQuery();
	}
	}

view raw

uploadfilestream.cs

hosted with ❤ by GitHub

Note that I replaced FileStream with the input stream present in the uploaded file itself.

P.S. I have tested the above code for files upto 50 MB. It depends largely on internet speed. Once for 50MB file size it gave me time out error (which could be fixed by setting RequestTimeout property of client context)

Hope this helps.

Reference:

1. O365 AMS