HttpClient

[ubkra]

I'm playing around with trying to get JSON data from an online source. It'll be the backbone of a little project I'm keen to build.

I'm getting a response when I run the application with errors commented out so I'm connecting okay.

In my code editor, responseString below has a red squiggly line, when I hover it says "'responseString' is not null here"

When I run the application I get

"Argument 1: cannot convert from 'System.Threading.Tasks.Task<string>' to 'System.IO.Stream'"

I've tried using NewtonSoft.Json as well, same response.

Any ideas?

        private async Task getPlayersAPI()
        {
            List<Player> playerList = new List<Player>();
            using (var httpClient = new HttpClient())
            {
                var response = await httpClient.GetAsync( _url );
                var responseString = response.Content.ReadAsStringAsync();
                playerList = JsonSerializer.Deserialize<List<Player>>(responseString);
                //playerList = JsonConvert.DeserializeObject<List<Player>>(responseString);
                testData.Text = responseString.ToString();
            }

[PlausiblyDamp]

Try

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

https://learn.microsoft.com/en-us/do...s-programming/
and
https://learn.microsoft.com/en-us/do...perators/await

are probably worth a look as they explain async methods and the await keyword.

[ubkra]

Sorry posted in VB.net not C# thanks for moving.

Yes, I was missing the await keyword. Just came back to update that and found the responses.

I'm not getting "Converting null literal or possible null value to non-nullable type." over this line,

playerList = JsonSerializer.Deserialize<List<Player>>(responseString);

And via try catch getting this when running the application

System.Text.Json.JsonException: The JSON value could not be converted to System.Collections.Generic.List`1[MyProgram.Classes.Player]. Path: $ | LineNumber: 0 | BytePositionInLine: 1.
   at System.Text.Json.ThrowHelper.ThrowJsonException_DeserializeUnableToConvertValue(Type propertyType)
   at System.Text.Json.Serialization.JsonCollectionConverter`2.OnTryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, TCollection& value)
   at System.Text.Json.Serialization.JsonConverter`1.TryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value, Boolean& isPopulatedValue)
   at System.Text.Json.Serialization.JsonConverter`1.ReadCore(Utf8JsonReader& reader, T& value, JsonSerializerOptions options, ReadStack& state)
   at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1.Deserialize(Utf8JsonReader& reader, ReadStack& state)
   at System.Text.Json.JsonSerializer.ReadFromSpan[TValue](ReadOnlySpan`1 utf8Json, JsonTypeInfo`1 jsonTypeInfo, Nullable`1 actualByteCount)
   at System.Text.Json.JsonSerializer.ReadFromSpan[TValue](ReadOnlySpan`1 json, JsonTypeInfo`1 jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Deserialize[TValue](String json, JsonSerializerOptions options)
   at MyProgram.PlayerList.getPlayersAPI() in C:\Users\bevan\source\repos\MyProgram\MyProgram\Pages\PlayerList.xaml.cs:line 55

My Player object is very simple

    public class Player
    {

        public int Id {  get; set; }
        public required string fullName { get; set; }

    }

JSON is like this

{"Players": [{"Id":5,"FullName":"Thomas Smith"},{"Id":74,"FullName":"John Anderson"}]}