问题
I work on application for fetching and downloading SharePoint data. For every folder in SharePoint I can get the list of all files inside given folder by using next SharePoint REST API endpoint:
/_api/web/GetFolderById('<folder_guid>')/Files
The expected size and guid is provided for every file so I can use them when I want to download the file. Then I use the next endpoint from SharePoint REST API in order to actually get file content:
/_api/web/GetFileById('<file_guid>')/$value
From time to time when I download the file I get less data than expected: size of downloaded data is just different from the value I obtain while getting the properties list of files. However when I try to get its content again it can be successfully downloaded (size of downloaded data is equal the expected value) or I can get another incomplete data.
I verified that the first endpoint (one used to get properties of all files in the folder) returns the correct file size. The problem is in the call of the second one.
I see that there is "transfer-encoding" header with "chunked" value in response. So when my http client performs chunked data download and if zero chunk is received at some point then we reached the end of the body by definition. So it looks like in some cases SharePoint either returns the incomplete data or zero chunks when they should not be sent.
What can be the reason of such strange behavior? Is it a know issue?
回答1:
We actually also see this, strange behaviour, many files are just small aspx files, about 3-4kb and they are constantly smaller by 15% and more than appears in file propertis. We're also using REST API and this is really frustrating. All those strange bugs in Sharepoint Online are very annoying.
回答2:
this is an interesting topic... are those files large? like over 1GB? It would seem that chunk file download is not supported way in SP Online. Better option is to user RPC. Please see this links for examples: https://sharepoint.stackexchange.com/questions/184789/download-large-files-from-sharepoint-online
https://social.msdn.microsoft.com/Forums/office/en-US/03e55d41-1daf-46a5-b61d-2d80139123f4/download-large-files-using-rest?forum=sharepointdevelopment
https://piyushksingh.com/2016/08/15/download-large-files-from-sharepoint-online/
You could also check the MS Graph API if maybe will work better for this case
https://docs.microsoft.com/en-us/graph/api/driveitem-get-content?view=graph-rest-1.0&tabs=http
... I hope this will be of any help
来源：https://stackoverflow.com/questions/59737754/sharepoint-rest-api-returns-incomplete-content-of-file-during-downloading