Question

I`m trying to perform a linq query in a friends JsonArray using Facebook C# SDK. So, i try:

var facebook = new FacebookWebClient();

dynamic facebookFriends = facebook.Get("me/friends");

JsonArray data = facebookFriends.data;

var friends = data.Where<JsonObject>(d => d["name"].ToString().StartsWith("D"));

But in the last line i get the following compile error:

“‘Facebook.JsonArray’ does not contain a definition for ‘Where’ and the best extension method overload ‘System.Linq.ParallelEnumerable.Where(System.Linq.ParallelQuery, System.Func)’ has some invalid arguments”

So, how can i do it?

Answer 1

You can’t use Where<JsonObject> because JsonArray is IEnumerable<JsonValue>, not IEnumerable<JsonObject>.

On the other hand, you don’t have to specify the type using Where<> extension method:

var friends = data.Where(d => d["name"].ToString().StartsWith("D"));

This will make d variable inside lambda expression be of JsonValue.

If you want iterate over JsonObject elements only you have to add OfType method before Where (but I haven’t really tested if it works):

var friends = data.OfType<JsonObject>().Where(d => d["name"].ToString().StartsWith("D"));