将json数组保存到c#类对象

Question

I have to assign json array of string to ac# class. I have done like below. But I got an exceptio

Cannot deserialize the current JSON array (eg [1,2,3]) into type 'LoggedInUserDetails' because the type requires a JSON object (eg {\\"name\\":\\"value\\"}) to deserialize correctly.\\r\\nTo 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.\\r\\nPath '', line 1, position 1."}

public class LoggedInUserDetails
{
    public string login_user_name
    {
        get; set;
    }

    public string login_user_id
    {
        get; set;
    }
}

 var GetResponse = await response2.Content.ReadAsStringAsync();
//"[{\"login_user_name\":\"Rahul\",\"login_user_id\":\"43\"}]"
 LoggedInUserDetails obj = JsonConvert.DeserializeObject<LoggedInUserDetails>(GetResponse);
 Variables.login_user_name = obj.login_user_name;
 Variables.login_user_id= obj.login_user_id;

Answer 1

You should deserialize the json string to an IEnumerable collection or Array .

 var content = await response2.Content.ReadAsStringAsync();
 var result = JsonConvert.DeserializeObject<List<LoggedInUserDetails>>(content);

Answer 2

It because of the '[]', which stores it as a array of results. You should be able to do something like the following:

LoggedInUserDetails obj = JsonConvert.DeserializeObject<List<LoggedInUserDetails>>(GetResponse);

where you try to deserialize object as an list. The list will only contain 1 object.

full example:

public class LoggedInUserDetails
{
    public string login_user_name
    {
        get; set;
    }

    public string login_user_id
    {
        get; set;
    }
}

 var GetResponse = await response2.Content.ReadAsStringAsync();
//"[{\"login_user_name\":\"Rahul\",\"login_user_id\":\"43\"}]"
 List<LoggedInUserDetails> obj = JsonConvert.DeserializeObject<List<LoggedInUserDetails>>(GetResponse);
 Variables.login_user_name = obj[0].login_user_name;
 Variables.login_user_id= obj[0].login_user_id;

Answer 3

This way:

LoggedInUserDetails obj = JsonConvert.DeserializeObject<LoggedInUserDetails[]>(GetResponse).FirstOrDefault() ?? throw new Exception("User not found.");
Variables.login_user_name = obj.login_user_name;
Variables.login_user_id = obj.login_user_id;

Your result was an array containing 1 object, so you just had to convert it to an array of your desired object and take the first.

Answer 4

Since you are using array, then it should deserialize array to list public class Test { public string login_user_name {get; set;} public string login_user_id { get; set;} }

string js =  "[{\"login_user_name\":\"Rahul\",\"login_user_id\":\"43\"}]";
var result  =  JsonConvert.DeserializeObject<List<Test>>(js);
foreach(var ob in result)
{
  Console.WriteLine(ob.login_user_name);
  Console.WriteLine(ob.login_user_id);
}

output

Rahul
43