Deserialize a JSON array in c# into a list

Question

I want to deserialize a json of this format into a List of objects. This is what my JSON looks like:

[{
        id : 3,
        vraag : "Op de keyserlei zijn er te weinig ...",
        fase_id : "1",
        antwoorden : [{
                id : 12,
                antwoord : "Bomen",
                inspraakvraag_id : "3",
                aantal_gekozen : "452"
            }, {
                id : 13,
                antwoord : "Vuilbakken",
                inspraakvraag_id : "3",
                aantal_gekozen : "777"
            }, {
                id : 14,
                antwoord : "Fietsstallingen",
                inspraakvraag_id : "3",
                aantal_gekozen : "456"
            }
        ]
    }, {
        id : 5,
        vraag : "Vind je dat er te veel geluidsoverlast in de binnenstad in het weekend",
        fase_id : "1",
        antwoorden : [{
                id : 18,
                antwoord : "Ja",
                inspraakvraag_id : "5",
                aantal_gekozen : "741"
            }, {
                id : 19,
                antwoord : "Nee",
                inspraakvraag_id : "5",
                aantal_gekozen : "147"
            }, {
                id : 20,
                antwoord : "Geen mening",
                inspraakvraag_id : "5",
                aantal_gekozen : "987"
            }
        ]
    }, {
        id : 4,
        vraag : "Welk van de volgende evenementen zou je graag zien op de groenplaats?",
        fase_id : "1",
        antwoorden : [{
                id : 15,
                antwoord : "Tuinbouw Expo",
                inspraakvraag_id : "4",
                aantal_gekozen : "785"
            }, {
                id : 16,
                antwoord : "Metal festival",
                inspraakvraag_id : "4",
                aantal_gekozen : "156"
            }, {
                id : 17,
                antwoord : "Counter strike LAN party",
                inspraakvraag_id : "4",
                aantal_gekozen : "456"
            }
        ]
    }, {
        id : 2,
        vraag : "In spark spoork noord zou ik graag ... zien",
        fase_id : "1",
        antwoorden : [{
                id : 6,
                antwoord : "Een speeltuin",
                inspraakvraag_id : "2",
                aantal_gekozen : "245"
            }, {
                id : 7,
                antwoord : "Een fabriek",
                inspraakvraag_id : "2",
                aantal_gekozen : "241"
            }, {
                id : 8,
                antwoord : "Een bos",
                inspraakvraag_id : "2",
                aantal_gekozen : "300"
            }
        ]
    }, {
        id : 1,
        vraag : "Voel je je 's avonds veilig in de stad Berchem?",
        fase_id : "1",
        antwoorden : [{
                id : 9,
                antwoord : "Ja",
                inspraakvraag_id : "1",
                aantal_gekozen : "452"
            }, {
                id : 10,
                antwoord : "Nee",
                inspraakvraag_id : "1",
                aantal_gekozen : "721"
            }, {
                id : 11,
                antwoord : "Niet van toepassing.",
                inspraakvraag_id : "1",
                aantal_gekozen : "123"
            }
        ]
    }
]

This is what my main code looks like:

var vraagTest = JsonUtility.FromJson<List<vraag>>(www.text);

my classes:

[System.Serializable]
public class vraag {

    public int id;
    public string vraagg;
    public int fase_id;
    public List<antwoorden> antwoorden;

}

and

[Serializable]
public class antwoorden {
    public int id;
    public string antwoord;
    public int inspraakvraag_id;
    public int aantal_gekozen;
}

I've tried some solutions on the internet but I keep getting the same error:

ArgumentException: JSON must represent an object type.

I've also tried putting the first list into a different class, but I get the same problem:

    [Serializable]
public class vragenlijst{
    public List<vragenlijst> vragen;
}

EDIT

I fixed the problem! I fixed it by wrappin the JSON around an object, apparently JsonUtility "does not support array types for top-level JSON deserialization (like Info[]). You need to wrap the JSON in an object".

This is my WORKING CODE:

{
vragen: [
{
id: 2,
vraag: "In spark spoork noord zou ik graag ... zien",
fase_id: "1",
antwoorden: [
{
id: 6,
antwoord: "Een speeltuin",
inspraakvraag_id: "2",
aantal_gekozen: "245"
},
{
id: 7,
antwoord: "Een fabriek",
inspraakvraag_id: "2",
aantal_gekozen: "241"
},
{
id: 8,
antwoord: "Een bos",
inspraakvraag_id: "2",
aantal_gekozen: "300"
}
]
},
{
id: 1,
vraag: "Voel je je 's avonds veilig in de stad Berchem?",
fase_id: "1",
antwoorden: [
{
id: 9,
antwoord: "Ja",
inspraakvraag_id: "1",
aantal_gekozen: "452"
},
{
id: 10,
antwoord: "Nee",
inspraakvraag_id: "1",
aantal_gekozen: "721"
},
{
id: 11,
antwoord: "Niet van toepassing.",
inspraakvraag_id: "1",
aantal_gekozen: "123"
}
]
},
{
id: 3,
vraag: "Op de keyserlei zijn er te weinig ...",
fase_id: "1",
antwoorden: [
{
id: 12,
antwoord: "Bomen",
inspraakvraag_id: "3",
aantal_gekozen: "452"
},
{
id: 13,
antwoord: "Vuilbakken",
inspraakvraag_id: "3",
aantal_gekozen: "777"
},
{
id: 14,
antwoord: "Fietsstallingen",
inspraakvraag_id: "3",
aantal_gekozen: "456"
}
]
}
]
}

Main code:

var vraagTest = JsonUtility.FromJson<vragenlijst>(www.text);

Classes:

[Serializable]
public class vragenlijst{
    public List<Vraag> vragen;
}

,

[System.Serializable]
public class Vraag {

    public int id;
    public string vraag;
    public int fase_id;
    public List<antwoorden> antwoorden;

}

,

[Serializable]
public class antwoorden {
    public int id;
    public string antwoord;
    public int inspraakvraag_id;
    public int aantal_gekozen;
}

vikky MCTS · Accepted Answer · 2016-05-27 13:58:35Z

2

[System.Serializable]
public class vraagClass
{

    public int id;
    public string vraag;
    public int fase_id;
    public List<antwoorden> antwoorden;

}
[Serializable]
public class antwoorden
{
    public int id;
    public string antwoord;
    public int inspraakvraag_id;
    public int aantal_gekozen;
}

[Serializable]
public class vragenlijst
{
    public List<vraagClass> vragen;
}
class Program
{
    static void Main(string[] args)
    {
        #region json
        string jsonText = "";

        #endregion

        using(StreamReader sr = new StreamReader(@"E:\WIP\DeserializeStackOverFlow\DeserializeStackOverFlow\Lib\abc.json"))
        {
            jsonText = sr.ReadToEnd();
        }


        var vraagTest = JsonConvert.DeserializeObject<List<vraagClass>>(jsonText);
    }
}

Just fix 2 things :

"vraag" Class can't have a property "vraag", so change the name of class [no issues as the json array isn't named ]
yeah as suggested by Bart, the deserializer needs to be List not the base "public List vragen;"

answered May 27, 2016 at 13:58

vikky MCTS

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2 Comments

Arne Over a year ago

I fixed it by adding { } around the JSON, apparently JsonUtility "does not support array types for top-level JSON deserialization (like Info[]). You need to wrap the JSON in an object". Thanks for help!

Arne Over a year ago

Wrap the JSOn array around an object* I meant

MakePeaceGreatAgain · Accepted Answer · 2016-05-27 14:19:48Z

2

I assume you will need a list of vraag instead of vragenlijst in your vragenlijst-class:

[Serializable]
public class vragenlijst{
    public List<vraag> vragen;
}

Then use

var vraagTest = JsonUtility.FromJson<vragenlijst>(www.text);

instead of

var vraagTest = JsonUtility.FromJson<List<vraag>>(www.text);

because the type you want to deserialize is vragenlijst, not List<vraag>.

edited May 27, 2016 at 14:19

answered May 27, 2016 at 13:34

MakePeaceGreatAgain

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4 Comments

Arne Over a year ago

I now have this: var vraagTest = JsonUtility.FromJson<vragenlijst>(www.text); and this: public class vragenlijst{ public List<vraagg> vragen; } but I still get the same error

MakePeaceGreatAgain Over a year ago

You need a list of vraag of course, vraagg is hopefully a typo, isn´t it?

Arne Over a year ago

I used that because I had a variable called vraag already, now I used a capital V instead. I did exactly what you said but I still get the same error :/

Arne Over a year ago

I fixed it by wrapping the JSON around an object, apparently JsonUtility "does not support array types for top-level JSON deserialization (like Info[]). You need to wrap the JSON in an object". Thanks for help!

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