best c# syntax/idiom, reading array of friends from Facebook

问题

In c#, I'm simply grabbing "/me/friends" from the FB api,

private void FacebookFriends()
    {
    FB.API("/me/friends", HttpMethod.GET, FBAPIFriendsCallback);
    }

private void FBAPIFriendsCallback(FBResult response)
    {
    // (error handling here - no problem)

    // ugly code...
    var dict = Json.Deserialize(response.Text)
        as Dictionary<string,object>;
    var friendList = new List<object>();
    friendList = (List<object>)(dict["data"]);
    int _friendCount = friendList.Count;

    // ugly code...
    // (example shows getting one item, would loop through all)
    string id = getDataValueForKey(
          (Dictionary<string,object>)(friendList[0]), "id" );
    string name = getDataValueForKey(
          (Dictionary<string,object>)(friendList[0]), "name" );
    }

Notice the very, very ugly code -- what's the more elegant way to write this? Cheers

---

In fact, per swazza's comment below, here's the full code passage:

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using Parse;
using System;
using Facebook;
using System.Threading.Tasks;
using System.IO;
using System.Linq;
using Facebook.MiniJSON;


public class ParseLinkOps : MonoBehaviour
  {

  ...

  public void GetFriendsFromFBThenMatch()
    {
    FB.API("/me/friends", HttpMethod.GET, _cbFriends);
    // FB calls at
    // https://developers.facebook.com/docs/unity/reference/current
    }

  private void _cbFriends(FBResult response)
    {
    // goal: given the json result from the cloud,
    // create a List<string> containing only the FacebookID "id" numbers

    if ( ! String.IsNullOrEmpty(response.Error) )
      { // .. error handling .. return; }

    var dict = Json.Deserialize(response.Text)
            as Dictionary<string,object>;

    var friendList = new List<object>();
    friendList = (List<object>)(dict["data"]);

    int _friendCount = friendList.Count;
    Debug.Log("Found friends on FB, _friendCount ... " +_friendCount);

    // so, convert that complex array of FB objects,
    // to simply an array of "id" strings
    // use very ugly code but assume someone on SO knows better later :-)

    List<string> friendIDsFromFB = new List<string>();

    for ( int k=0; k<_friendCount; ++k)
      {
      string friendFBID =
        getDataValueForKey( (Dictionary<string,object>)(friendList[k]), "id");

      string friendName =
        getDataValueForKey( (Dictionary<string,object>)(friendList[k]), "name");

      Debug.Log( k +"/" +_friendCount +" " +friendFBID +" " +friendName);

      friendIDsFromFB.Add( friendFBID );
      }

    // we're done, the list is in friendIDsFromFB
    StartCoroutine( _match( friendIDsFromFB ) );
    }

  ...
  }

回答1:

How about using linq extensions?

var dict = new Dictionary<string, object>();
var friend = dict
            .Where(s => s.Key.Equals("data"))
            .Select(s => new { Id = s.Key, Name = s.Value })
            .First();

var friendId = friend.Id;
var friendName = friend.Name;

Here is a linq extension to iterate over an enumerable and perform an action on each element -

public static void Execute<TSource>(this IEnumerable<TSource> source, Action<TSource> actionToExecute)
{
    if (source.Count() > 0)
    {
        foreach (var item in source)
        {
            actionToExecute(item);
        }
    }
}

EDIT: So I understand that you are using this in Unity game engine. Its been ages since I worked on Unity. Glad to know they have support for Linq now. So here is the code that I wrote that get the friendIds. There is some code that is specific to ASP.Net but the linq part should work anywhere -

// Use ASP.Net's Javascript serializer to desrialize the json response received from 
// call to graph.facebook.com/me/friends
var jsSerializer = new JavaScriptSerializer();
var jsonString = "{ \"data\": [ { \"name\": \"name1\", \"id\": \"id1\" }, { \"name\": \"name2\", \"id\": \"id2\" } ] }";

// Deserialize the json to type - Dictionary<string, object>
var dict = jsSerializer.Deserialize(jsonString, typeof(Dictionary<string, object>)) as Dictionary<string, object>;

/*Code upto here is specific to ASP.Net - At this point, be it ASP.Net or Unity, we have a dictionary that contains a key "data" which again contains a dictionaries of name value pairs*/

// The code from below is Linq and should work on Unity as well.
var friendIds = (dict["data"] as ArrayList)                     // Convert the "data" key of the dictionary into its underlying type (which is an ArrayList in this case)
                .Cast<Dictionary<string, object>>()             // ArrayList is not generic. Cast it to a generic enumerable where each element is of type Dictionary<string, object> 
               .Select(s =>
                            {
                                // Each element in the cast enumerable is of type dictionary.
                                // Each dictionary has two keys - "id" and "name" that correspond to the id and name properties 
                                // of the json response received when calling graph.facebook.com/me/friends.
                                // check - https://developers.facebook.com/tools/explorer/145634995501895/?method=GET&path=me%2Ffriends&version=v2.0
                                // Because we only want Ids, fetch the value corresponding to the "id" key
                                object id = null;
                                if (s.TryGetValue("id", out id))
                                {
                                    return id.ToString();
                                }

                                return string.Empty;
                            });

I put in verbose comments to make that code a bit self explanatory. If you remove the comments, it makes for concise code. However, this is less performant than a plain for loop.

来源：https://stackoverflow.com/questions/23431622/best-c-sharp-syntax-idiom-reading-array-of-friends-from-facebook