Graph REST AddMember to Group - Bad Request - microsoft-graph-api

Question

I am attempting to add members to a group. I am able to list all groups in my org, get user by email, get all users and I can even remove a Member from a group but I cannot add one - The error returned is 400 Bad Request.
Here is the function which is the same function signature as those that work: (I do have the accesstoken, valid group id and a valid member id)
I have confirmed the body data looks correct at least as far as I can see from the example in the docs.
Not sure what else I can add to make things clearer, ask and I'll update
public async Task<string> AddGroupMember(string accessToken, string groupId, string memberId)
{
var status = string.Empty;
string endpoint = $"https://graph.microsoft.com/v1.0/groups/{groupId}/members/$ref";
string queryParameter = "";
// pass body data
var keyOdataId = "#odata.id";
var valueODataId = $"https://graph.microsoft.com/v1.0/directoryObjects/{memberId}";
var values = new List<KeyValuePair<string, string>>
{
new KeyValuePair<string, string>(keyOdataId, valueODataId)
};
var body = new FormUrlEncodedContent(values);
try
{
using(var client = new HttpClient())
{
using(var request = new HttpRequestMessage(HttpMethod.Post, endpoint + queryParameter))
{
request.Content = body;
request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);
using(var response = await client.SendAsync(request))
{
if (response.StatusCode == HttpStatusCode.NoContent)
status = "Member added to Group";
else
status = $"Unable to add Member to Group: {response.StatusCode}";
}
}
}
}
catch (Exception ex)
{
status = $"Error adding Member to Group: {ex.Message}";
}
return status;
}
Thanks for any help that anyone can offer - this is the last call I have to make then home free

Answer 1

Found the issue for any who care to know for the future:
var body = new FormUrl... my code was incorrect, what's needed is a simple json string changed to this UPDATED:
var jsonData = $#"{{ ""{keyOdataId}"": ""{valueODataId}"" }}";
var body = new StringContent(jsonData, Encoding.UTF8, "application/json");
I would normally put the values in a class but this is for proof of concept and the json key needs to look exactly like this #odata.id

Answer 2

Clarifying what is happening here:
The request body for this call should be JSON encoded (application/json). The FormUrlEncodedContent method returns your dictionary as Form encoded (application/x-www-form-urlencoded).
You can write the JSON by hand (like you have so far) but a better solution would be to leverage Json.NET. This will let you encode the dictionary in much the same way you were with FormUrlEncodedContent:
var values = new Dictionary<string, string>
{
{ keyOdataId, valueODataId}
};
var body = JsonConvert.SerializeObject(values);
If you're going to be doing a lot of work with Microsoft Graph, I would highly recommend switching to the Microsoft Graph .NET SDK.
You're method here would be far simpler using the SDK:
public async Task<string> AddGroupMember(string groupId, string memberId)
{
GraphServiceClient graphClient = AuthenticationHelper.GetAuthenticatedClient();
User userToAdd = new User { Id = memberId };
await graphClient.Groups[groupId].Members.References.Request().AddAsync(userToAdd);
}