firstusage.cs

public class FirstUsageModel : PageModel
{
    private readonly IHttpClientFactory _clientFactory;

    public IEnumerable<User> Users { get; private set; }

    public bool GetUsersError { get; private set; }

    public BasicUsageModel(IHttpClientFactory clientFactory)
    {
        _clientFactory = clientFactory;
    }

    public async Task OnGet()
    {
        var request = new HttpRequestMessage(HttpMethod.Get,
            "https://api.example.com/users");
        request.Headers.Add("Accept", "application/json");
        request.Headers.Add("User-Agent", "HttpClientFactory-Sample");

        var client = _clientFactory.CreateClient();

        var response = await client.SendAsync(request);

        if (response.IsSuccessStatusCode)
        {
            using var responseStream = await response.Content.ReadAsStreamAsync();
            Users = await JsonSerializer.DeserializeAsync
                <IEnumerable<User>>(responseStream);
        }
        else
        {
            GetUsersError = true;
            Users = Array.Empty<User>();
        }
    }
}