Can't access JEnumerable<JToken> children

Question

if I try to call code below as it is, I receive

,"Name":"Newtonsoft.Json.Linq.JEnumerable`1[Newtonsoft.Json.Linq.JToken]"

as result. If I change the related line to

var property = myObject[propertyNames.Last()].FirstOrDefault();

then I receive

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

any idea about what the problem might be and/or workaround? Thanks...

Stack Trace

• at Newtonsoft.Json.Linq.JToken.get_Item(Object key)
• at Newtonsoft.Json.Linq.Extensions.d__4`2.MoveNext()
• at System.Linq.Enumerable.d__14`2.MoveNext()
• at Newtonsoft.Json.Linq.Extensions.d__f`2.MoveNext()
• at Newtonsoft.Json.Linq.Extensions.d__4`2.MoveNext()
• at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable`1 source)

Code

void Main()
{
    JObject objects = JObject.Parse("{\"Main\":[{\"Sub\":[{\"FieldName\":\"TEST\"}]}]}");
    Console.WriteLine (SetProperty(objects, "Name", "Main", "Sub", "FieldName"));
}

private static string SetProperty(JObject objects, string propertyKey, params string[] propertyNames)
{
    var myObject = objects.AsJEnumerable();

    for (int counter = 0; counter < propertyNames.Count()-1; counter++)
    {
        myObject = myObject[propertyNames[counter]].Children();
    }   
    var property = myObject[propertyNames.Last()];

    string propertyValue = property == null
                            ? string.Empty
                            : property.ToString();
    string output = string.Format(",\"{0}\":\"{1}\"", propertyKey, propertyValue);
    return output;
}

Answer 1

I'm making some assumptions about how your data is structured. Also, you really shouldn't build JSON manually, which you appear to be doing at the end there. Instead, I'm returning a KeyValuePair that can be added to a dictionary for serialization.

private static KeyValuePair<string, string> GetProperty(JObject objects,
                    string propertyKey, params string[] propertyNames)
{
    JToken token = objects[propertyNames.First()];
    foreach (var name in propertyNames.Skip(1))
        token = token[0][name];
    return new KeyValuePair<string, string>(propertyKey, (string)token);
}
// returns [Name, TEST]