事先不知道密钥的情况下，如何在 C# 中解析 JSON 对象？

Question

我有一些如下所示的 JSON 数据：

{
  "910719": {
    "id": 910719,
    "type": "asdf",
    "ref_id": 7568
  },
  "910721": {
    "id": 910721,
    "type": "asdf",
    "ref_id": 7568
  },
  "910723": {
    "id": 910723,
    "type": "asdf",
    "ref_id": 7568
  }
}

如何使用 JSON.net 解析它？我可以先这样做：

JObject jFoo = JObject.Parse(data);

我需要能够遍历此列表中的每个对象。我希望能够做这样的事情：

foreach (string ref_id in (string)jFoo["ref_id"]) {...}

或

foreach (JToken t in jFoo.Descendants())
{
    Console.WriteLine((string)t["ref_id"]);
}

但这当然行不通。如果您在编写代码时知道密钥，那么所有示例都非常有用。当您事先不知道密钥时，它就会崩溃。

Answer 1

这是可行的；这可行，但并不优雅。我确信有更好的方法。

var o = JObject.Parse(yourJsonString);

foreach (JToken child in o.Children())
{
    foreach (JToken grandChild in child)
    {
        foreach (JToken grandGrandChild in grandChild)
        {
            var property = grandGrandChild as JProperty;

            if (property != null)
            {
                Console.WriteLine(property.Name + ":" + property.Value);
            }
        }
    }
}

打印：

id:910719
类型：asdf
ref_id:7568
编号:910721
类型：asdf
ref_id:7568
编号:910723
类型：asdf
ref_id:7568

Answer 2

您可以像这样使用简单的 LINQ 查询来遍历子对象：

JObject jFoo = JObject.Parse(json);

foreach (JObject obj in jFoo.Properties().Select(p => p.Value))
{
    Console.WriteLine("id: " + obj["id"]);
    Console.WriteLine("type: " + obj["type"]);
    Console.WriteLine("ref_id: " + obj["ref_id"]);
}

小提琴：https://dotnetfiddle.net/fwINPa

或者，如果您只想要所有 ref_id 值，您可以执行以下操作：

string[] refIds = jFoo.Properties()
                      .Select(p => (string)p.Value["ref_id"])
                      .ToArray();

Console.Write(string.Join("\r\n", refIds));

小提琴：https://dotnetfiddle.net/twOuVY

Answer 3

我正在使用 Json.NET，我编写了一种快速方法，您可以使用递归方法打印出所有键和相应的值。

      var o = JObject.Parse(YourJsonString);
      getAllProperties(o); //call our recursive method

然后你可以使用这个递归的方法来获取所有的属性和它们的值

   void getAllProperties(JToken children)
    {
        foreach (JToken child in children.Children())
        {
            var property = child as JProperty;
            if (property != null)
            {
                Console.WriteLine(property.Name + " " + property.Value);//print all of the values
            }
            getAllProperties(child);
        }
    }

Answer 4

您是否考虑过使用 JavascriptSerializer？

你可以尝试做这样的事情：

JavaScriptSerializer serializer = new JavaScriptSerializer();
var foo = serializer.Deserialize<Dictionary<string, Dictionary<string, string>>>(data);
foreach(var item in foo)
{
    Console.Writeln(item.Value["ref_id"]);
}

http://msdn.microsoft.com/en-us/library/system.web.script.serialization.javascriptserializer.aspx

Answer 5

Konstantin 的解决方案会起作用，但如果你想要一个 Id 列表做同样的事情，而不是 Console.Writeln() 使用以下

List<string> list = new List<string>();
JavaScriptSerializer serializer = new JavaScriptSerializer();
var foo = serializer.Deserialize<Dictionary<string, Dictionary<string, string>>>(data);
foreach(var item in foo)
{
    list.Add(item.Value["ref_id"]);
}

Answer 6

我发现 TrueWill 的答案有效，但我想避免使用 foreach 并尝试使用一个简单的 for 循环来提高速度。我的结果肯定是充其量只能说是丑陋的。它们在这里，以防它们对任何人有用。 （我离开 WriteLine 是为了更容易看清事物。）

请注意，这不适用于某些 JSON，也不是完全通用的。一些空检查可以做得更好，等等。

       // NOW, DOING IT ALL AS A FOR LOOP...
        // a, b, c, d - for iterator counters.
        // j1, j2, j3, j4 - the JTokens to iterator over - each is a child of the previous
        // p, q, r, s - The properties from j1/2/3/4. 

        JObject o = JObject.Parse(json);
        JToken j1 = o.First;
        for (int a = 0; a < o.Children().Count(); a++) { // Outermost loop gives us result, error, id. 
            if (j1 == null)
                continue;
            if (a > 0) {
                j1 = j1.Next;
                if (j1 == null)
                    continue;
            } 
            var p = j1 as JProperty;
            Console.WriteLine("FOR 0 = " + a.ToString() + " --- " + p.Name);
            // DO STUFF HERE.

            // FIRST INNER LOOP
            // Set up a JToken or continue
            JToken j2 = j1.Children().First() as JToken;
            if (j1.Children().Count() > 0) {
                j2 = j1.Children().First() as JToken;
            } else {
                continue;
            }
            Console.WriteLine("*** STARTING FIRST INNER...");
            for (int b = 0; b < j1.Children().Count(); b++) { // returns nothing as second loop above.
                if (j2 == null) {
                    Console.WriteLine("*** j2 null 1...");
                    continue;
                }
                if (b > 0) {
                    j2 = j2.Next;
                    if (j2 == null) {
                        Console.WriteLine("*** j2 null 2...");
                        continue;
                    }
                }
                var q = j2 as JProperty;
                // These null checks need to be != or ==, depending on what's needed. 
                if (q != null) {
                    Console.WriteLine("FOR 1 = " + a.ToString() + ","
                      + b.ToString() + " --- " + q.Name);
                    // DO STUFF HERE.
                    // ...
                } // q !null check

                // SECOND INNER LOOP
                // Set up a JToken or continue
                JToken j3;
                if (j2.Children().Count() > 0) {
                    j3 = j2.Children().First() as JToken;
                } else {
                    continue;
                }
                Console.WriteLine("****** STARTING SECOND INNER...");
                for (int c = 0; c < j2.Children().Count(); c++) {
                    if (j3 == null)
                        continue;
                    if (c > 0) {
                        j3 = j3.Next;
                        if (j3 == null)
                            continue;
                    }
                    var r = j3 as JProperty;
                    if (r == null) {
                        continue;
                    } // r null check

                    Console.WriteLine("FOR 2 = "
                        + a.ToString() + ","
                        + b.ToString() + ","
                        + c.ToString() + " --- " + r.Name);
                    // DO STUFF HERE.

                    // THIRD INNER LOOP
                    // Set up a JToken or continue
                    JToken j4;
                    if (j3.Children().Count() > 0) {
                        j4 = j3.Children().First() as JToken;
                    } else {
                        continue;
                    }

                    Console.WriteLine("********* STARTING THIRD INNER...");
                    for (int d = 0; d < j3.Children().Count(); d++) {
                        if (j4 == null)
                            continue;
                        if (c > 0) {
                            j4 = j4.Next;
                            if (j4 == null)
                                continue;
                        }
                        var s = j4 as JProperty;
                        if (s == null) {
                            continue;
                        } // s null check

                        Console.WriteLine("FOR 3 = "
                            + a.ToString() + ","
                            + b.ToString() + ","
                            + c.ToString() + ","
                            + d.ToString() + " --- " + s.Name);
                        // DO STUFF HERE.
                        // ...

                    } // for d - j3
                } // for c - j2
            } // for b - j1
        } // for a - original JObject