无法将 JSON 数组（例如 [1,2,3]）反序列化为类型“ ”，因为类型需要 JSON 对象（例如 {"name":"value"}）才能正确反序列化

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 (eg [1,2,3]) into type 'test.Model.RetrieveMultipleResponse' because the type requires a JSON object (eg {"name":"value"}) to deserialize correctly. To fix this error either change the JSON to a JSON object (eg {"name":"value"}) or change the deserialized type to an array or a type that implements a collection interface (eg 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.

Answer 1

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

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

Answer 2

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;

Answer 3

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

Answer 4

Use this, FrontData is JSON string:

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

and extract list:

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

Answer 5

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();
            }
        }

Answer 6

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

worked!