How to get permissions for SharePoint files on Office 365 - sharepoint

Question

In Office365, we are uploading a file “File1” to OneDrive using the user “UserA”. We then are getting the permissions of that file using the graph api (https://graph.microsoft.com/me/drives/[DriveId]/items/[itemId]/permissions) and get back permissions as we would expect:
"permissions": [
{
"grantedTo": {
"user": {
"email": "UserA#wherever.com",
"id": "ef7bd4af-3f36-4e81-9f76-296f4956b807",
"displayName": "User A"
}
},
"id": "aTowIy5mfG1lbWJlcnNoaXB8ZGRyYXBlckBmaXJlbGF5ZXJzLm9ubWljcm9zb2Z0LmNvbQ",
"roles": [
"owner"
]
}
]
However, we are then uploading the same file (using the same user) to a newly created SharePoint site named “Site1” and getting the permissions for that file (again using the graph api). Unlike with the OneDrive file permissions, the permissions returned for this SharePoint file do NOT contain “UserA” but include only 3 site-specific groups (which seem to be created automatically when creating a new SharePoint site)
"permissions": [
{
"grantedTo": {
"user": {
"displayName": "Site1 Owners"
}
},
"id": "QXRoYXlUZXN0IE93bmVycw",
"roles": [
"owner"
]
},
{
"grantedTo": {
"user": {
"displayName": " Site1 Visitors"
}
},
"id": "QXRoYXlUZXN0IFZpc2l0b3Jz",
"roles": [
"read"
]
},
{
"grantedTo": {
"user": {
"displayName": " Site1 Members"
}
},
"id": "QXRoYXlUZXN0IE1lbWJlcnM",
"roles": [
"write"
]
}
]
When listing all groups for the SharePoint site, none of these 3 groups are listed. A group named “Site1” does however but doesn’t contain any users added to any of these 3 groups.
How do we get additional information for these groups (i.e. the users who are a part of a given group) using the graph API / is that even possible?

Answer 1

I am not sure that it is possible via the Graph API but SharePoint does have a RESTful API that focuses on users and groups and that should be helpful. It does include extensive examples here:
https://msdn.microsoft.com/en-us/library/office/dn531432.aspx