Add user to SharePoint group using Power Automate - http

Question

I would like to use Power Automate to add a user in as a member to a SharePoint Site using HTTP request.
The flow continues to fail on me and I'm wondering if anyone managed to do this successfully in the past?
I got the Group ID from :
https://{org name}.sharepoint.com/sites/{site name}/_api/web/id
I have attached included the input and output of the HTTP Request (within flow) below
Raw Inputs
{
"host": {
"connectionReferenceName": "shared_sharepointonline",
"operationId": "HttpRequest"
},
"parameters": {
"dataset": "https://{REDACTED}.sharepoint.com/",
"parameters/method": "POST",
"parameters/uri": "_api/web/sitegroups(547ea631-f9d4-411a-a3f5-8af3d5e6225b)/Users",
"parameters/headers": {
"accept": "application/json;odata.metadata=none",
"content-type": "application/json"
},
"parameters/body": "{'LoginName':'i:0#.f|membership|{REDACTED}#{REDACTED}.com'}"
}
}
Raw Outputs
{
"statusCode": 400,
"headers": {
"Pragma": "no-cache",
"x-ms-request-id": "cb6ab59f-909a-2000-ac2f-2217e416179a",
"Strict-Transport-Security": "max-age=31536000; includeSubDomains",
"X-Content-Type-Options": "nosniff",
"X-Frame-Options": "DENY",
"Cache-Control": "no-store, no-cache",
"Set-Cookie": "{REDACTED};Path=/;HttpOnly;Secure;Domain=sharepointonline-we.azconn-we.p.azurewebsites.net,ARRAffinitySameSite={REDACTED}24;Path=/;HttpOnly;SameSite=None;Secure;Domain=sharepointonline-we.azconn-we.p.azurewebsites.net",
"Timing-Allow-Origin": "*",
"x-ms-apihub-cached-response": "true",
"Date": "{TIME & DATE}",
"Content-Length": "457",
"Content-Type": "application/json",
"Expires": "-1"
},
"body": {
"status": 400,
"message": "The expression \"web/sitegroups(547ea631-f9d4-411a-a3f5-8af3d5e6225b)/Users\" is not valid.\r\nclientRequestId: 1cc16a39-7d9c-4290-b07d-4c7329611fb8\r\nserviceRequestId: cb6ab59f-909a-2000-ac2f-2217e416179a",
"source": "https://{REDACTED}.sharepoint.com/_api/web/sitegroups(547ea631-f9d4-411a-a3f5-8af3d5e6225b)/Users",
"errors": [
"-1",
"Microsoft.SharePoint.Client.InvalidClientQueryException"
]
}
}
The error I get is:
"The expression "web/sitegroups(547ea631-f9d4-411a-a3f5-8af3d5e6225b)/Users" is not valid.
clientRequestId: 1cc16a39-7d9c-4290-b07d-4c7329611fb8
serviceRequestId: cb6ab59f-909a-2000-ac2f-2217e416179a"
This makes me think the group ID is incorrect. Can someone please advise if this is incorrect or if I have maybe formatted the uri incorrectly?

Answer 1

Try to use the body like this:
{
'__metadata': {
// Type that you are modifying.
'type': 'SP.User'
},
'LoginName': '<<User Login Name>>'
}