Unity Engine freezes when Accessing Task<Token>.Result-CodePudding

I have implemented some code to access an oauth 2.0 protected api. The Unity Engine freezes as soon as I hit "play" button. and I have to close it via Task Manager.

My Code:

public class importFromAPI : MonoBehaviour
{
    // Start is called before the first frame update
    void Start()
    {
        HttpClient client = new HttpClient();
        Task<Token> task = GetElibilityToken(client);
        //Token token = task.Result;
    }

    // Update is called once per frame
    void Update()
    {

    }


    // OAuth Stuff




    private static async Task<Token> GetElibilityToken(HttpClient client)
{
    string baseAddress = @"*REDACTED*/oauth/token";

    string grant_type = "client_credentials";
    string client_id = "*REDACTED*";
    string client_secret = "*REDACTED*";
    string audience = "*REDACTED*";

    var form = new Dictionary<string, string>
        {
            {"grant_type", grant_type},
            {"client_id", client_id},
            {"client_secret", client_secret},
            {"audience", audience }
        };

    HttpResponseMessage tokenResponse = await client.PostAsync(baseAddress, new FormUrlEncodedContent(form));
        var jsonContent = await tokenResponse.Content.ReadAsStringAsync();
        Debug.Log("Response: "   jsonContent);
        Token tok = JsonConvert.DeserializeObject<Token>(jsonContent);
    Debug.Log(tok.ToString());
    return tok;
}


internal class Token
{
    [JsonProperty("access_token")]
    public string AccessToken { get; set; }

    [JsonProperty("token_type")]
    public string TokenType { get; set; }

    [JsonProperty("expires_in")]
    public int ExpiresIn { get; set; }

    [JsonProperty("refresh_token")]
    public string RefreshToken { get; set; }

    override
    public string ToString()
    {
        return "AccessToken: "   AccessToken   "; TokenType: "   TokenType   "; Expires in: "   ExpiresIn   "; Refresh Token: "   RefreshToken;
    }
}
}

Removing task.Result from the Start() method stops Unity from freezing on pressing the button, but I want to get the token to access the api afterwards.

Can anyone tell me why Unity freezes?

CodePudding user response：

You need to use the await keyword, something like this:

Token task = await GetElibilityToken(client);

However you need to change the method as well, something like this:

async Task Start()

Actually it's been recommended to use async all the way down always. You can find more information in this topic here.

https://gametorrahod.com/unity-and-async-await/

EDIT: Based on the comments, it seems we are not allowed to change or redefine the Unity's Start to be async Task, so in this case I would still use the async void, despite the fact that it is not been recommended https://docs.microsoft.com/en-us/archive/msdn-magazine/2013/march/async-await-best-practices-in-asynchronous-programming

async void Start()