public Task <IEnumerable <ExcelViewModel> > GetDataAsync()
        {
            // How to url-encode query-string parameters properly
            var uri = new UriBuilderExt(new Uri(_httpClient.BaseAddress, "/api/getDataList"))
                      //.AddParameter("checkInDate", $"{checkInDate:yyyy'-'MM'-'dd}")
                      //.AddParameter("checkOutDate", $"{checkOutDate:yyyy'-'MM'-'dd}")
                      .Uri;

            return(_httpClient.GetFromJsonAsync <IEnumerable <ExcelViewModel> >(uri));
        }
        public async Task <Book> FindBookByIsbn(string isbn)
        {
            _client = new HttpClient();
            _client.DefaultRequestHeaders.Add("Accept", "application/json");

            // need JWT
            var jwt = "Bearer " + _credentialsService.Jwt;

            _client.DefaultRequestHeaders.Add("Authorization", jwt);

            try
            {
                var values = new Dictionary <string, string>
                {
                    { "isbn", isbn }
                };
                // var url = String.Empty;  //QueryHelpers.AddQueryString(EnvironmentSettings.ApiUrl + "/api/backlog/search", values);

                var builder = new UriBuilderExt(EnvironmentSettings.ApiUrl + "/api/backlog/search");
                builder.AddParameter("isbn", isbn);
                var response = await _client.GetAsync(builder.Uri);

                var returnContent = await response.Content.ReadAsStringAsync();

                if (response.IsSuccessStatusCode)
                {
                    return(JsonConvert.DeserializeObject <Book>(returnContent));
                }
                var error = JsonConvert.DeserializeObject <ApiError>(returnContent);
                throw new Exception(error.message);
            }
            catch (HttpRequestException e)
            {
                Debug.WriteLine(e.Message);
                throw new Exception($"HTTP errors: {e.Message}");
            }
        }