Blazor application is getting Forbidden (403) when calling an external API (which works fine in PostMan) - outlook-restapi

Question

Visual Studio 2019, .NET 3.0 preview, Created a blazor application. Trying to get weather data from https://api.weather.gov/gridpoints/ALY/59,14/forecast.
I am using HttpClient in C#. This is getting forbidden (403) response
Tried to add CORS policty
private async Task<IWeatherDotGovForecast> RetrieveForecast()
{
string url = #"https://api.weather.gov/gridpoints/ALY/59,14/forecast";
var response = await _httpClient.GetAsync(url);
if (response != null)
{
var jsonString = await response.Content.ReadAsStringAsync();
return JsonConvert.DeserializeObject<WeatherDotGovForecast>(jsonString);
}
//return await _httpClient.GetJsonAsync<WeatherDotGovForecast>
// ("https://api.weather.gov/gridpoints/ALY/59,14/forecast");
return null;
}
I expected JSON data from https://api.weather.gov/gridpoints/ALY/59,14/forecast
Instead, I am getting Forbidden (403) status code

Answer 1

Your problem is not related to Blazor but weather.gov requires a User-Agent header in any HTTP request.
Applications accessing resources on weather.gov now need to provide a User-Agent header in any HTTP request. Requests without a user agent are automatically blocked. We have implemented this usage policy due to a small number of clients utilizing resources far in excess of what most would consider reasonable.
Use something like this:
var _httpClient = new HttpClient();
string url = #"https://api.weather.gov/gridpoints/ALY/59,14/forecast";
_httpClient.DefaultRequestHeaders.Add("User-Agent", "posterlagerkarte");
var response = await _httpClient.GetAsync(url);