[C#] Slack Message 보내기

1. Slack 채널 만든 후 https://api.slack.com/apps 에서 앱 만들기

2. 퍼미션 설정

3. WebHook Url 만들기

4. WebhookUrl = 위에서 copy한 url

        public async static Task<bool> SendMessageAsync(string message, string slackUrl = WebhookUrl)
        {
            string paramJson = System.Text.Json.JsonSerializer.Serialize(new { text = message });

            // Payload
            var content = new System.Net.Http.FormUrlEncodedContent(new Dictionary<string, string>
            {
                { "payload", paramJson }
            });

            // POST!!
            using System.Net.Http.HttpClient _httpClient = new System.Net.Http.HttpClient();

            System.Net.Http.HttpResponseMessage res = await _httpClient.PostAsync(slackUrl, content);

            return (res.StatusCode == System.Net.HttpStatusCode.OK);
        }