C# How to handle NULL json values? Getting and InvalidOperationException: Cannot access child value on > Newtonsoft.Json.Linq.JValue

Question

I am having trouble handling nulls in my json file. As you can see in the following photo the null value is under player:

This unfortunately is causing the following InvalidOperationException:

System.InvalidOperationException: Cannot access child value on Newtonsoft.Json.Linq.JValue. at Newtonsoft.Json.Linq.JToken.get_Item(Object key) at WindowsFormsApplication2.Starting_Lineups.StartingLineups() in C:\Users\Administrator\documents\visual studio 2015\Projects\WindowsFormsApplication2\WindowsFormsApplication2\Starting Lineups.cs:line 97

I tried the following How to ignore a property in class if null, using json.net but have been unsuccessful.

JSON:

{"gamestartinglineup":{"lastUpdatedOn":"2017-10-24 11:41:12 AM","game":{"id":"42120","date":"2017-10-24","time":"7:30PM","awayTeam":{"ID":"83","City":"New York","Name":"Knicks","Abbreviation":"NYK"},"homeTeam":{"ID":"82","City":"Boston","Name":"Celtics","Abbreviation":"BOS"},"location":"TD Garden"},"teamLineup":[{"team":{"ID":"83","City":"New York","Name":"Knicks","Abbreviation":"NYK"},"expected":{"starter":[{"position":"Bench8","player":null},{"position":"Starter1","player":{"ID":"9087","LastName":"Hardaway Jr.","FirstName":"Tim","JerseyNumber":"3","Position":"SG"}},{"position":"Starter2","player":{"ID":"9373","LastName":"Porzingis","FirstName":"Kristaps","JerseyNumber":"6","Position":"PF"}},{"position":"Starter5","player":{"ID":"9518","LastName":"Sessions","FirstName":"Ramon","JerseyNumber":"1","Position":"PG"}},{"position":"Starter3","player":{"ID":"9396","LastName":"Kanter","FirstName":"Enes","JerseyNumber":"0","Position":"C"}},{"position":"Starter4","player":{"ID":"9127","LastName":"Lee","FirstName":"Courtney","JerseyNumber":"1","Position":"SG"}},{"position":"Bench1","player":{"ID":"9148","LastName":"McDermott","FirstName":"Doug","JerseyNumber":"20","Position":"SF"}},{"position":"Bench2","player":{"ID":"9376","LastName":"O'Quinn","FirstName":"Kyle","JerseyNumber":"9","Position":"PF"}},{"position":"Bench3","player":{"ID":"9245","LastName":"Beasley","FirstName":"Michael","JerseyNumber":"9","Position":"F"}},{"position":"Bench4","player":{"ID":"10102","LastName":"Baker","FirstName":"Ron","JerseyNumber":"31","Position":"G"}},{"position":"Bench5","player":null},{"position":"Bench6","player":null},{"position":"Bench7","player":null}]},"actual":null},{"team":{"ID":"82","City":"Boston","Name":"Celtics","Abbreviation":"BOS"},"expected":{"starter":[{"position":"Bench8","player":null},{"position":"Starter1","player":{"ID":"13730","LastName":"Tatum","FirstName":"Jayson","JerseyNumber":"0","Position":"F"}},{"position":"Starter2","player":{"ID":"9082","LastName":"Horford","FirstName":"Al","JerseyNumber":"15","Position":"C"}},{"position":"Starter5","player":{"ID":"9157","LastName":"Irving","FirstName":"Kyrie","JerseyNumber":"11","Position":"PG"}},{"position":"Starter3","player":{"ID":"9211","LastName":"Baynes","FirstName":"Aron","JerseyNumber":"12","Position":"C"}},{"position":"Starter4","player":{"ID":"10090","LastName":"Brown","FirstName":"Jaylen","JerseyNumber":"7","Position":"SF"}},{"position":"Bench1","player":{"ID":"13777","LastName":"Theis","FirstName":"Daniel","JerseyNumber":"27","Position":"PF"}},{"position":"Bench2","player":{"ID":"9105","LastName":"Rozier","FirstName":"Terry","JerseyNumber":"12","Position":"PG"}},{"position":"Bench3","player":{"ID":"13770","LastName":"Nader","FirstName":"Abdel","JerseyNumber":"28","Position":"SF"}},{"position":"Bench4","player":{"ID":"9120","LastName":"Larkin","FirstName":"Shane","JerseyNumber":"8","Position":"PG"}},{"position":"Bench5","player":{"ID":"13778","LastName":"Yabusele","FirstName":"Guerschon","JerseyNumber":"30","Position":"PF"}},{"position":"Bench6","player":{"ID":"13771","LastName":"Bird","FirstName":"Jabari","JerseyNumber":"26","Position":"SG"}},{"position":"Bench7","player":null}]},"actual":null}]}}

Code:

    public void StartingLineups()
    {
        upass.upass up = new upass.upass();
        string address3 = "https://api.mysportsfeeds.com/v1.1/pull/nba/2017-2018-regular/game_startinglineup.json?gameid=" + dateTimePicker1.Text + comboBox2.Text;

        var w3 = new WebClient();
        w3.UseDefaultCredentials = true;
        w3.Credentials = new NetworkCredential(up.username, up.password);
        var result3 = w3.DownloadString(address3);

        var obj3 = JObject.Parse(result3);


        StartingLineup.startinglineup sl = new StartingLineup.startinglineup();

        try
       {

            foreach (JToken child in obj3 ["gamestartinglineup"]["teamLineup"])
            {


                    foreach (JToken sub in child["expected"]["starter"])
                    {

                    JsonConvert.SerializeObject(sub,
                        Newtonsoft.Json.Formatting.None,
                        new JsonSerializerSettings
                        {
                            NullValueHandling = NullValueHandling.Ignore
                        });

                    sl.player = sub["player"]["FirstName"].ToString() + " " + sub["player"]["LastName"].ToString();
                        sl.team = child["team"]["City"].ToString() + " " + child["team"]["Name"].ToString();
                        sl.position = sub["position"].ToString();
                        sl.playerpositon = sub["player"]["Position"].ToString();




                        DataRow row = dt.NewRow();
                        row["Team"] = sl.team;
                        row["Player"] = sl.player;
                        row["Position"] = sl.playerpositon;





                        if (sl.position.Contains("Starter"))
                        {
                            row["Role"] = sl.position;
                        }
                        else
                        {
                            row["Role"] = "NOPE";
                        }



                        dt.Rows.Add(row);
                    }
                    dataGridView1.DataSource = dt;

                    DataRow[] drr = dt.Select("Role='NOPE'");
                    for (int i = 0; i < drr.Length; i++)
                        drr[i].Delete();
                    dt.AcceptChanges();




                }



        }
        catch (Exception e)
        {
            MessageBox.Show(e.ToString());

        }

    }

Why are doing nothing with the output string of JsonConvert.SerializeObject(sub, Newtonsoft.Json.Formatting.None, new JsonSerializerSettings { NullValueHandling = NullValueHandling.Ignore });? — Teneko
– Teneko, Commented Oct 24, 2017 at 22:27
You still have to check for null. It's no different than expecting myNullObject.ChildProperty to succeed. NullValueHandling.Ignore just means that if the value is null, the property won't exist when you serialize to JSON. — TyCobb
– TyCobb, Commented Oct 24, 2017 at 22:28

Teneko · Accepted Answer · 2017-10-24 22:57:45Z

3

Consider this, when checking for nullable values (Value<T>(Object key)):

var testObj = new Newtonsoft.Json.Linq.JObject();

if (testObj.TryGetValue("player", out Newtonsoft.Json.Linq.JToken token)) {
 string yourString = token.Value<string>("FirstName"); // can be null
 int? yourNullableInt = token.Value<int?>("AnyNumber"); // can be null
 int yourInt = token.Value<int?>("AnyNumber") ?? 0; // can be 0 if null
 int yourInt = token.SelectToken("firstLayer")?.SelectToken("secondLayer")?.Value<int?>("anyNumber") ?? 0; // return value by path
}

SelectToken is also applicable on Newtonsoft.Json.Linq.JObject.

edited Oct 24, 2017 at 22:57

answered Oct 24, 2017 at 22:38

Teneko

1,5009 silver badges20 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

C# How to handle NULL json values? Getting and InvalidOperationException: Cannot access child value on > Newtonsoft.Json.Linq.JValue

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related