【C#】Dynamics Business Central向けAPIでOAuth2.0を使用

Business Centralへデータ編集やデータ取得を行うAPIにOAuth2.0を用いてtokenや認証を行う。
AzureのApp Registryの設定や、Business Centralの認証の設定は、こちらに詳しく記載があるので、こちでは、C#側でHttpClientを使用したBusiness Central API実行ロジックを紹介する。

            var client = new HttpClient();
            client.DefaultRequestHeaders.Accept.Clear();

            string url = "https://login.microsoftonline.com/<テナントID>/oauth2/v2.0/token";
            string accessToken = string.Empty;
            Uri uri = new Uri(url);
            Dictionary<string, string> requestBody = new Dictionary<string, string>
                {
                    {"grant_type", "client_credentials" },
                    {"client_id" , "AzureからApplication IDを取得" },
                    {"client_secret", "AzureからSecret Valueを取得" },
                    {"scope", "https://api.businesscentral.dynamics.com/.default" }
                };
            FormUrlEncodedContent request = new FormUrlEncodedContent(requestBody);
            try
            {
                HttpResponseMessage response = await client.PostAsync(uri, request);
                string content = await response.Content.ReadAsStringAsync();
                if (response.IsSuccessStatusCode)
                {
                    JsonDocument document = JsonDocument.Parse(content);
                    accessToken = document.RootElement.GetProperty("access_token").GetString();

                }
                else
                {
                }
            }
            catch (Exception ex)
            {
            }

            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);

            var response = await client.PostAsync("Business CentralのAPI URL", new StringContent(JsonConvert.SerializeObject("request用のJSON"),Encoding.UTF8, "application/json"));
            var resString = await response.Content.ReadAsStringAsync();