Cannot deserialize the JSON array (e.g. [1,2,3]) into type ' ' because type requires JSON object (e.g. {"name":"value"}) to deserialize correctly

Question

I have this JSON:

[
    {
        "Attributes": [
            {
                "Key": "Name",
                "Value": {
                    "Value": "Acc 1",
                    "Values": [
                        "Acc 1"
                    ]
                }
            },
            {
                "Key": "Id",
                "Value": {
                    "Value": "1",
                    "Values": [
                        "1"
                    ]
                }
            }
        ],
        "Name": "account",
        "Id": "1"
    },
    {
        "Attributes": [
            {
                "Key": "Name",
                "Value": {
                    "Value": "Acc 2",
                    "Values": [
                        "Acc 2"
                    ]
                }
            },
            {
                "Key": "Id",
                "Value": {
                    "Value": "2",
                    "Values": [
                        "2"
                    ]
                }
            }
        ],
        "Name": "account",
        "Id": "2"
    },
    {
        "Attributes": [
            {
                "Key": "Name",
                "Value": {
                    "Value": "Acc 3",
                    "Values": [
                        "Acc 3"
                    ]
                }
            },
            {
                "Key": "Id",
                "Value": {
                    "Value": "3",
                    "Values": [
                        "3"
                    ]
                }
            }
        ],
        "Name": "account",
        "Id": "2"
    }
]

And I have these classes:

public class RetrieveMultipleResponse
{
    public List<Attribute> Attributes { get; set; }
    public string Name { get; set; }
    public string Id { get; set; }
}

public class Value
{
    [JsonProperty("Value")]
    public string value { get; set; }
    public List<string> Values { get; set; }
}

public class Attribute
{
    public string Key { get; set; }
    public Value Value { get; set; }
}

I am trying to deserialize the above JSON using the code below:

var objResponse1 = JsonConvert.DeserializeObject<RetrieveMultipleResponse>(JsonStr);

but I am getting this error:

Cannot deserialize the current JSON array (e.g. [1,2,3]) into type 'test.Model.RetrieveMultipleResponse' because the type requires a JSON object (e.g. {"name":"value"}) to deserialize correctly. To fix this error either change the JSON to a JSON object (e.g. {"name":"value"}) or change the deserialized type to an array or a type that implements a collection interface (e.g. ICollection, IList) like List that can be deserialized from a JSON array. JsonArrayAttribute can also be added to the type to force it to deserialize from a JSON array. Path '', line 1, position 1.

TylerH · Accepted Answer · 2024-03-20 13:19:45Z

274

Your JSON string is wrapped within square brackets ([]), hence it is interpreted as an array instead of as a single RetrieveMultipleResponse object. Therefore, you need to deserialize it to a type of collection of RetrieveMultipleResponse, for example:

var objResponse1 = 
    JsonConvert.DeserializeObject<List<RetrieveMultipleResponse>>(JsonStr);

edited Mar 20, 2024 at 13:19

TylerH

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answered Mar 21, 2014 at 11:40

har07

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2 Comments

Rich Over a year ago

If you wanted to keep it as a single object instead of a collection, could you just do JsonStr.Replace("[","").Replace("]","") or would this not be good practice?

Aamir Over a year ago

This solution is not working when serialized from DataTable and then deserializing back to DataTable. Getting the same error when deserializing because the JSON is an array.

Shimmy Weitzhandler · Accepted Answer · 2018-02-10 23:19:28Z

14

If one wants to support Generics (in an extension method) this is the pattern...

public  static List<T> Deserialize<T>(this string SerializedJSONString)
{
    var stuff = JsonConvert.DeserializeObject<List<T>>(SerializedJSONString);
    return stuff;
}

It is used like this:

var rc = new MyHttpClient(URL);
//This response is the JSON Array (see posts above)
var response = rc.SendRequest();
var data = response.Deserialize<MyClassType>();

MyClassType looks like this (must match name value pairs of JSON array)

[JsonObject(MemberSerialization = MemberSerialization.OptIn)]
 public class MyClassType
 {
    [JsonProperty(PropertyName = "Id")]
    public string Id { get; set; }

    [JsonProperty(PropertyName = "Name")]
    public string Name { get; set; }

    [JsonProperty(PropertyName = "Description")]
    public string Description { get; set; }

    [JsonProperty(PropertyName = "Manager")]
    public string Manager { get; set; }

    [JsonProperty(PropertyName = "LastUpdate")]
    public DateTime LastUpdate { get; set; }
 }

Use NUGET to download Newtonsoft.Json add a reference where needed...

using Newtonsoft.Json;

edited Feb 10, 2018 at 23:19

Shimmy Weitzhandler

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answered Mar 3, 2015 at 17:39

JWP

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2 Comments

TylerH Over a year ago

What are generics and why would one want to support them? How does this answer the question asked? Where does this code come from? This looks like an answer to a totally different question.

TylerH Over a year ago

To get more specific, OP already has all of this structure set up (more or less correctly) in their question. Their issue is a type disparity between their JSON and their C# and they need help resolving it. This answer currently doesn't explain which part of it solves OP's problem or how.

H. Pauwelyn · Accepted Answer · 2018-07-04 11:43:48Z

6

Can't add a comment to the solution but that didn't work for me. The solution that worked for me was to use:

var des = (MyClass)Newtonsoft.Json.JsonConvert.DeserializeObject(response, typeof(MyClass)); 
return des.data.Count.ToString();

Deserializing JSON array into strongly typed .NET object

edited Jul 4, 2018 at 11:43

H. Pauwelyn

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answered Apr 11, 2017 at 16:22

TheNerdyNerd

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1 Comment

TylerH Over a year ago

"Can't add a comment to the solution" What solution are you referring to?

groenhen · Accepted Answer · 2020-08-18 05:39:20Z

2

Use this, FrontData is JSON string:

var objResponse1 = JsonConvert.DeserializeObject<List<DataTransfer>>(FrontData);

and extract list:

var a = objResponse1[0];
var b = a.CustomerData;

edited Aug 18, 2020 at 5:39

groenhen

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answered Aug 18, 2020 at 2:37

udorb b

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Comments

TylerH · Accepted Answer · 2024-03-20 13:24:52Z

0

To extract the first element (Key) try this method and it will be the same for the others:

using (var httpClient = new HttpClient())
{
    using (var response = await httpClient.GetAsync("Your URL"))
    {
        var apiResponse = await response.Content.ReadAsStringAsync();
        var list = JObject.Parse(apiResponse)["Attributes"].Select(el => new {  Key= (string)el["Key"] }).ToList();
        var Keys= list.Select(p => p.Key).ToList();
    }
}

edited Mar 20, 2024 at 13:24

TylerH

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answered May 6, 2021 at 1:23

Ahmadou Kassoum

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