我有这行代码（总是返回1）：
int rowsCount = token["rows"].Count();
其中token [“ rows”]是：
{ "component": [ { "tag": "CUT", "missingValue": "", "format": "Cont", "varName": "GPA", "label": "Grade point average", "element": [ { "startValue": "1", "endValue": "249", "label": "Lower than 2.50" }, { "startValue": "250", "endValue": "299", "label": "2.50 - 2.99" }, { "startValue": "300", "endValue": "349", "label": "3.00 - 3.49" }, { "startValue": "350", "endValue": "400", "label": "3.50 or higher" } ] }, { "tag": "CAT", "missingValue": "", "format": "Disc", "varName": "STEMMAJ", "label": "Major field of study with a focus on STEM fields", "element": [ { "value": "1", "label": "Math/Computer/Sciences/Engineering/Technologies" }, { "value": "2", "label": "Social/behavioral sciences" }, { "value": "4", "label": "Non-STEM field" }, { "value": "5", "label": "Undecided or not in a degree program" } ] } ] }
我想对组件数量进行计数。
这也不起作用：
token["rows"]["component"].Count();
整个JSON在这里：
{ "version": "1.0", "createdBy": "PowerStats v1.0", "test": "ohoh", "DSNumber": { "value": "82" }, "title": { "value": "" }, "footnote": { "value": "" }, "flagRSE": { "value": "30,50", "symbol": "!,!!" }, "weight": { "type": "0", "varName": "WTA000", "label": "weight_var" }, "filters": { "filter_1": { "component": { "varName": "JOBEARN2", "filterType": "Range", "format": "Cont", "label": "Job: Earnings from work while enrolled (including work-study)", "element": { "startValue": "1", "endValue": "", "label": "X >= 1" } } }, "filter_2": { "component": { "varName": "JOBROLE2", "filterType": "Dist", "format": "Disc", "label": "Job: Primary role as student or employee (including work-study)", "element": { "value": "1", "label": "A student working to meet expenses" } } } }, "columns": { "component": { "tag": "CAT", "missingValue": "4,5,6,7,8,9,10,13,14,15,16,17,18,19,20,21,22,23,-3", "format": "Disc", "varName": "MAJORS23", "label": "Field of study: undergraduate (23 categories)", "element": [ { "value": "0", "label": "Undecided" }, { "value": "1", "label": "Computer and information sciences" }, { "value": "2", "label": "Engineering and engineering technology" }, { "value": "3", "label": "Biological and physical science, science tech" }, { "value": "11", "label": "Personal and consumer services" }, { "value": "12", "label": "Manufacturing,construction,repair & transportation" } ] } }, "rows": { "component": [ { "tag": "CUT", "missingValue": "", "format": "Cont", "varName": "GPA", "label": "Grade point average", "element": [ { "startValue": "1", "endValue": "249", "label": "Lower than 2.50" }, { "startValue": "250", "endValue": "299", "label": "2.50 - 2.99" }, { "startValue": "300", "endValue": "349", "label": "3.00 - 3.49" }, { "startValue": "350", "endValue": "400", "label": "3.50 or higher" } ] }, { "tag": "CAT", "missingValue": "", "format": "Disc", "varName": "STEMMAJ", "label": "Major field of study with a focus on STEM fields", "element": [ { "value": "1", "label": "Math/Computer/Sciences/Engineering/Technologies" }, { "value": "2", "label": "Social/behavioral sciences" }, { "value": "4", "label": "Non-STEM field" }, { "value": "5", "label": "Undecided or not in a degree program" } ] } ] } }
根据您在另一个答案中的评论，我现在可以了解您为什么感到困惑。您没有在问题中提到正在执行XML到JSON的转换。
如您所知，XML不像JSON那样具有“对象”或“数组”的概念。在XML中，所有内容都只是命名节点的集合。在确定某个东西应该是数组还是对象时，JSON.net会检查在同一级别上是否存在多个具有相同名称的节点。如果有的话，那显然是一个数组。但是，如果一个节点只有一个孩子，那就是模棱两可的。它可以是一个单项的数组，也可以只是一个简单的对象属性。默认情况下，Json.Net选择后者。如果XML中的结果数量可以从零到很多变化，那么转换为JSON时，处理起来会更加困难。
为了说明，请考虑以下XML。在其中，我们有三个不同的“集合”，每个集合中都有不同数量的“项目”。第一批只有一个孩子。第二个有两个，最后一个为空。
<root> <collection1> <item> <label>A</label> <value>1</value> </item> </collection1> <collection2> <item> <label>B</label> <value>2</value> </item> <item> <label>C</label> <value>3</value> </item> </collection2> <collection3 /> </root>
使用进行转换时JsonConvert.SerializeXmlNode()，我们得到以下JSON：
JsonConvert.SerializeXmlNode()
{ "collection1": { "item": { "label": "A", "value": "1" } }, "collection2": { "item": [ { "label": "B", "value": "2" }, { "label": "C", "value": "3" } ] }, "collection3": null }
请注意，在第一个集合中，项目已成为父集合对象的属性，而在第二种情况下，项目已放置在数组中，并且该数组已成item为父对象的属性值。（换句话说，实际项目在JSON结构中位于 下一层 ！）最后一个集合根本没有item属性；它只包含一个属性。它的值为null。
item
null
那么我们如何处理呢？我们真正需要的是一个帮助程序方法，该方法将处理所有这些不同的情况，并为我们提供JArray可以一致使用的项目（例如）的集合。
JArray
这是应该起作用的扩展方法：
public static class JsonHelper { public static JArray ToJArray(this JToken token, string itemProperty) { if (token != null && token.Type != JTokenType.Null) { token = token[itemProperty]; if (token != null) { if (token.Type == JTokenType.Array) { return (JArray)token; } else { return new JArray(token); } } } return new JArray(); } }
这是一个演示，演示了如何使用此帮助方法打印项目列表：
class Program { static void Main(string[] args) { string json = @" { ""collection1"": { ""item"": { ""label"": ""A"", ""value"": ""1"" } }, ""collection2"": { ""item"": [ { ""label"": ""B"", ""value"": ""2"" }, { ""label"": ""C"", ""value"": ""3"" } ] }, ""collection3"": null }"; JObject root = JObject.Parse(json); DumpItems(root, "collection1"); DumpItems(root, "collection2"); DumpItems(root, "collection3"); } private static void DumpItems(JToken token, string collectionName) { JArray array = token[collectionName].ToJArray("item"); Console.WriteLine("Count of items in " + collectionName + ": " + array.Count); foreach (JToken item in array) { Console.WriteLine(item["label"] + ": " + item["value"]); } } }
输出：
Count of items in collection1: 1 A: 1 Count of items in collection2: 2 B: 2 C: 3 Count of items in collection3: 0
回到原来的问题，您现在应该可以执行以下操作：
var count = token["rows"].ToJArray("component").Count;
并获得您期望的价值。
