Parse JSON String into List<string>

Question

string json = "{\"People\":[{\"FirstName\":\"Hans\",\"LastName\":\"Olo\"}
                            {\"FirstName\":\"Jimmy\",\"LastName\":\"Crackedcorn\"}]}";

var obj = JObject.Parse(json);

List<string> first;
List<string> last;

foreach (var child in obj["People"].Children())
{
    var name = child.First()["countryName"].ToString();
    var two = child.First()["countryCode"].ToString();
    var three = child.First()["isoAlpha3"].ToString();

    countries.Add(name);
    twoCharCodes.Add(two);
    threeCharCodes.Add(three);

    Console.Write("Name:\t\t{0}\n2CharCode:\t{1}\n3CharCode:\t{2}\n\n", name, two, three);
}

I'm looking for a way to add each FirstName value into the first List and the same with the LastName vaues and the last List. What is the best way to go about doing this?

The above code breaks on:

var name = child.First()["countryName"].ToString();

with this error:

 Cannot access child value on Newtonsoft.Json.Linq.JProperty

Any advice?

Answer 1

Since you are using JSON.NET, personally I would go with serialization so that you can have Intellisense support for your object. You'll need a class that represents your JSON structure. You can build this by hand, or you can use something like json2csharp to generate it for you:

e.g.

public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

public class RootObject
{
    public List<Person> People { get; set; }
}

Then, you can simply call JsonConvert's methods to deserialize the JSON into an object:

RootObject instance = JsonConvert.Deserialize<RootObject>(json);

Then you have Intellisense:

var firstName = instance.People[0].FirstName;
var lastName = instance.People[0].LastName;

Answer 2

Seems like a bad way to do it (creating two correlated lists) but I'm assuming you have your reasons.

I'd parse the JSON string (which has a typo in your example, it's missing a comma between the two objects) into a strongly-typed object and then use a couple of LINQ queries to get the two lists.

void Main()
{
    string json = "{\"People\":[{\"FirstName\":\"Hans\",\"LastName\":\"Olo\"},{\"FirstName\":\"Jimmy\",\"LastName\":\"Crackedcorn\"}]}";

    var result = JsonConvert.DeserializeObject<RootObject>(json);

    var firstNames = result.People.Select (p => p.FirstName).ToList();
    var lastNames = result.People.Select (p => p.LastName).ToList();
}

public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

public class RootObject
{
    public List<Person> People { get; set; }
}