How to create an appRoleAssignment via Microsoft Graph?

Question

As per this documentation you should be able to create an appRoleAssignment via Microsoft Graph, however this doesn't work. In a GitHub issue I was instructed to create the issue here. We have migrated most of our code from Azure Graph API to Microsoft Graph and this is the last piece that is missing.

Answer 1

This finally worked for me!

There might be more optimized ways to post the JSON but I had to go to basics to make sure nothing is causing this to fail behind the scenes.

        const string ROLE_ASSIGNMENT_FORMATTER = "https://graph.microsoft.com/beta/servicePrincipals/{0}/appRoleAssignments";

        public static async Task AddApplicationUsers(string enterpriseAppId, string userId, string roleId)
        {
            HttpClient client = new HttpClient();
            string url = string.Format(ROLE_ASSIGNMENT_FORMATTER, enterpriseAppId);

            client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", await GetAccessToken());

            var roleAssignment = new
            {
                appRoleId = roleId,
                principalId = userId,
                resourceId = enterpriseAppId
            };


            var content = new StringContent(Newtonsoft.Json.JsonConvert.SerializeObject(roleAssignment), Encoding.UTF8, "application/json");
            content.Headers.ContentType = new MediaTypeHeaderValue("application/json");
            var response  = await client.PostAsync(url, content);

            if (response.IsSuccessStatusCode)
            {
                return ;
            }
            else
            {
                throw new HttpRequestException(response.ReasonPhrase);
            }
        }