REST Call to Sharepoint Online to add user to a site group not working. Either user not unique or Value not in range

Question

I got a REST API call to our SP Online Instance that is not working in any way:

Method: POST

Endpoint: https://xyz.sharepoint.com/sites/ATestSite/_api/web/sitegroups(5)/users

Header:

Accept application/json;odata.metadata=none
Content-type application/json

Content:

{'LoginName':'i:0#.f|membership|xxx.yyy@zzz.com'}

This results in a 400 error: Value does not fall within the expected range. I got the login name from the system when I looked up the siteuser through REST

if I change the content to {'LoginName':'xxx.yyy@zzz.com'} I get a 404 error: The user does not exist or is not unique.

Anybody got any idea? Thanks in advance!

Answer 1

You can try following format

Post https://xyz.sharepoint.com/sites/ATestSite/_api/web/sitegroups(5)/users

{ 
    '__metadata': 
{ 'type': 'SP.User' }, 
    'LoginName':'i:0#.f|membership|user@domain.com'
}

Answer 2

Try using below code. I just tried this at my end and it is working for me:

<script type="text/javascript" src="/sites/siteName/SiteAssets/jquery.min.js"></script>

<button type="button" onclick="addUserToGroup()"> Add User To Group </button>

<script type="text/javascript">
    function addUserToGroup() {
        var addUserToGroupEndpoint = _spPageContextInfo.webAbsoluteUrl + "/_api/web/sitegroups(38)/users";

        var payload = JSON.stringify({
            '__metadata': { 'type': 'SP.User' },
            'LoginName': 'i:0#.f|membership|meganb@tenant.onmicrosoft.com'
        });

        $.ajax({
            url: addUserToGroupEndpoint,
            type: "POST",
            data: payload,
            headers: {
                "X-RequestDigest": $("#__REQUESTDIGEST").val(),
                "accept": "application/json;odata=verbose",
                "content-type": "application/json;odata=verbose"
            },
            success: function (data) {
                console.log("User Added to Group successfully!");
            },
            error: function (error) {
                console.log(error);
            }
        });
    }
</script>

Verify and use correct user LoginName in payload and group ID from your SharePoint site in REST endpoint.