Deserialise JSON with Newtonsoft Json.NET in C#

Question

I want to parse a piece of JSON with Newtonsoft Json.NET

JSON:

[{
"type": "switchStatus",
"Data" :[
            { 
            "ID" : "1",
            "value" : "2.5"
        },
        { 
            "ID" : "2",
            "value" : "4.2"
        }
    ],
"Datetime": "2014-12-01",
"customerID": "50"
}]

Classes:

public class Account
{
    [JsonProperty("type")]
    public string Type { get; set; }
    public List<Data> Data { get; set; }
    [JsonProperty("Datetime")]
    public string DateTime { get; set; }
    [JsonProperty("customerID")]
    public string CustomerId { get; set; }
}//Account

public class Data
{
    [JsonProperty("ID")]
    public string Id { get; set; }
    [JsonProperty("value")]
    public string Value { get; set; }
}

Parsing:

Account account = JsonConvert.DeserializeObject<Account>(message);

Error :

Cannot deserialize the current JSON array (e.g. [1,2,3]) into type 'JSonParser.Account' 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.

Yuval Itzchakov · Accepted Answer · 2015-04-26 07:26:17Z

5

Your problem is that your JSON doesn't match your declared class. Specifically, your Data property isn't a List<string>, its a complex object.

Your class should look like this:

public class Data
{
    [JsonProperty("ID")]
    public int Id { get; set; }
    [JsonProperty("value")]
    public double Value { get; set; }
}

public class Account
{
    [JsonProperty("type")]
    public string Type { get; set; }
    public List<Data> Data { get; set; }
    [JsonProperty("Datetime")]
    public string DateTime { get; set; }
    [JsonProperty("customerID")]
    public int CustomerId { get; set; }
}

Edit:

As you've edited your JSON, it's clear now that you need a List<Account>, and not a single one. When you deserialize, you'll need:

List<Account> accounts = JsonConvert.DeserializeObject<List<Account>>(message);

edited Apr 26, 2015 at 7:26

answered Apr 26, 2015 at 7:12

Yuval Itzchakov

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6 Comments

SreekanthGS Over a year ago

My reply is identical to @YuvalItzchakov while his is more accurate.

Yuval Itzchakov Over a year ago

@SajjadZare I've tested this code and it works. Are you sure you're running the correct code?

Yuval Itzchakov Over a year ago

@SajjadZare You only copy and pasted my code. I don't follow you. I've run this code and it works fine. Are you still getting the same error?

Marian Polacek Over a year ago

posted JSON is an array of Account objects, so problem is also in deserialize call.

Yuval Itzchakov Over a year ago

@SajjadZare My answer has a "Edit" in bold. Look at it.

|

SreekanthGS · Accepted Answer · 2015-04-26 07:19:23Z

1

You cannot Deserialize the data Data attribute like that. Since the list isnt a string to start with.

Try:

public class Data
{
    public int ID { get; set; }
    public float value { get; set; }
}//Data

public class Account
{
    public string type { get; set; }
    public List<Data> Data { get; set; }
    public string Datetime { get; set; }
    public string customerID { get; set; }
}//Account

edited Apr 26, 2015 at 7:19

answered Apr 26, 2015 at 7:15

SreekanthGS

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1 Comment

Yuval Itzchakov Over a year ago

If you declare value as an int, you're truncating any decimal point.

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