如何访问 JArray 的元素（或迭代它们）
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【中文标题】如何访问 JArray 的元素（或迭代它们）【英文标题】：How to access elements of a JArray (or iterate over them) 【发布时间】：2013-04-09 08:40:10 【问题描述】：我有以下从 Twitter 获得的 Json
+ token [
"trends": [
"name": "Croke Park II",
"url": "http://twitter.com/search?q=%22Croke+Park+II%22",
"promoted_content": null,
"query": "%22Croke+Park+II%22",
"events": null
,
"name": "#twiznight",
"url": "http://twitter.com/search?q=%23twiznight",
"promoted_content": null,
"query": "%23twiznight",
"events": null
,
"name": "#Phanhattan",
"url": "http://twitter.com/search?q=%23Phanhattan",
"promoted_content": null,
"query": "%23Phanhattan",
"events": null
,
"name": "#VinB",
"url": "http://twitter.com/search?q=%23VinB",
"promoted_content": null,
"query": "%23VinB",
"events": null
,
"name": "#Boston",
"url": "http://twitter.com/search?q=%23Boston",
"promoted_content": null,
"query": "%23Boston",
"events": null
,
"name": "#rtept",
"url": "http://twitter.com/search?q=%23rtept",
"promoted_content": null,
"query": "%23rtept",
"events": null
,
"name": "Facebook",
"url": "http://twitter.com/search?q=Facebook",
"promoted_content": null,
"query": "Facebook",
"events": null
,
"name": "Ireland",
"url": "http://twitter.com/search?q=Ireland",
"promoted_content": null,
"query": "Ireland",
"events": null
,
"name": "Everton",
"url": "http://twitter.com/search?q=Everton",
"promoted_content": null,
"query": "Everton",
"events": null
,
"name": "Twitter",
"url": "http://twitter.com/search?q=Twitter",
"promoted_content": null,
"query": "Twitter",
"events": null
],
"as_of": "2013-04-17T13:05:30Z",
"created_at": "2013-04-17T12:51:41Z",
"locations": [
"name": "Dublin",
"woeid": 560743
]
] Newtonsoft.Json.Linq.JToken Newtonsoft.Json.Linq.JArray
问题是我似乎无法访问任何元素。我已经尝试过 foreach 循环和正常的 for 循环，但似乎永远无法访问单个元素，它总是最终访问整个区域。
知道如何访问这个 Json JArray 中的各个元素吗？
【问题讨论】：
【参考方案1】：对此有一个更简单的解决方案。
只需将JArray 的项目视为JObject。
假设我们有这样的 JSON 对象数组：
JArray jArray = JArray.Parse(@"[
""name"": ""Croke Park II"",
""url"": ""http://twitter.com/search?q=%22Croke+Park+II%22"",
""promoted_content"": null,
""query"": ""%22Croke+Park+II%22"",
""events"": null
,
""name"": ""Siptu"",
""url"": ""http://twitter.com/search?q=Siptu"",
""promoted_content"": null,
""query"": ""Siptu"",
""events"": null
]");
要访问每个项目，只需执行以下操作：
foreach (JObject item in jArray) // <-- Note that here we used JObject instead of usual JProperty
string name = item.GetValue("name").ToString();
string url = item.GetValue("url").ToString();
// ...
【讨论】：
这实际上是我在 3 个帖子中看到的最直接的答案 @deeps，可能是您传递给 GetValue() 的参数不正确。您能否为您的案例提供更多详细信息？ @Just Shadow 谢谢，这是我的错。现在可以正常使用了。【参考方案2】：更新 - 我验证了以下工作。也许您的 JArray 的创建不太正确。
[TestMethod]
public void TestJson()
var jsonString = @"""trends"": [
""name"": ""Croke Park II"",
""url"": ""http://twitter.com/search?q=%22Croke+Park+II%22"",
""promoted_content"": null,
""query"": ""%22Croke+Park+II%22"",
""events"": null
,
""name"": ""Siptu"",
""url"": ""http://twitter.com/search?q=Siptu"",
""promoted_content"": null,
""query"": ""Siptu"",
""events"": null
,
""name"": ""#HNCJ"",
""url"": ""http://twitter.com/search?q=%23HNCJ"",
""promoted_content"": null,
""query"": ""%23HNCJ"",
""events"": null
,
""name"": ""Boston"",
""url"": ""http://twitter.com/search?q=Boston"",
""promoted_content"": null,
""query"": ""Boston"",
""events"": null
,
""name"": ""#prayforboston"",
""url"": ""http://twitter.com/search?q=%23prayforboston"",
""promoted_content"": null,
""query"": ""%23prayforboston"",
""events"": null
,
""name"": ""#TheMrsCarterShow"",
""url"": ""http://twitter.com/search?q=%23TheMrsCarterShow"",
""promoted_content"": null,
""query"": ""%23TheMrsCarterShow"",
""events"": null
,
""name"": ""#Raw"",
""url"": ""http://twitter.com/search?q=%23Raw"",
""promoted_content"": null,
""query"": ""%23Raw"",
""events"": null
,
""name"": ""Iran"",
""url"": ""http://twitter.com/search?q=Iran"",
""promoted_content"": null,
""query"": ""Iran"",
""events"": null
,
""name"": ""#gaa"",
""url"": ""http://twitter.com/search?q=%23gaa"",
""promoted_content"": null,
""query"": ""gaa"",
""events"": null
,
""name"": ""Facebook"",
""url"": ""http://twitter.com/search?q=Facebook"",
""promoted_content"": null,
""query"": ""Facebook"",
""events"": null
]";
var twitterObject = JToken.Parse(jsonString);
var trendsArray = twitterObject.Children<JProperty>().FirstOrDefault(x => x.Name == "trends").Value;
foreach (var item in trendsArray.Children())
var itemProperties = item.Children<JProperty>();
//you could do a foreach or a linq here depending on what you need to do exactly with the value
var myElement = itemProperties.FirstOrDefault(x => x.Name == "url");
var myElementValue = myElement.Value; ////This is a JValue type
所以调用 JArray 上的 Children 以获取 JArray 中的每个 JObject。在每个 JObject 上调用 Children 以访问对象属性。
foreach(var item in yourJArray.Children())
var itemProperties = item.Children<JProperty>();
//you could do a foreach or a linq here depending on what you need to do exactly with the value
var myElement = itemProperties.FirstOrDefault(x => x.Name == "url");
var myElementValue = myElement.Value; ////This is a JValue type
【讨论】：
我想我对你所说的有大致的了解。但是，如果我运行此代码，我最终会获得对 myElementValue 的空引用。或者，如果我在 myElement 上执行 foreach 循环，则 json 结构保持不变，并且我仍然面临多个元素。就好像数组本身格式错误或其他什么，因为它拒绝被迭代。 查看我更新的问题，准确显示我将响应解析为 JArray 时得到的结果 尝试将 json 字符串响应解析为 JToken 而不是 JArray。 现在更新了 JToken 解析的输出。与您的字符串不太匹配【参考方案3】：一旦你有了一个 JArray，你就可以像对待任何其他 Enumerable 对象一样对待它， 并且使用 linq 你可以访问它们、检查它们、验证它们并选择它们。
var str = @"[1, 2, 3]";
var jArray = JArray.Parse(str);
Console.WriteLine(String.Join("-", jArray.Where(i => (int)i > 1).Select(i => i.ToString())));
【讨论】：
【参考方案4】：void ConvertToJArray(object headers)
//where headers is your Twitter response
JObject JObj = (JObject)headers;//Parse to JObject
JArray JArr = (JArray)JObj["trends"];//Get the trends array as JArray
for (int i = 0; i < JArr.Count; i++)
var Name = JArr[i]["name"].ToString();
var URL = JArr[i]["url"].ToString();
【讨论】：
虽然此代码可能会回答问题，但提供有关此代码为何和/或如何回答问题的额外上下文可提高其长期价值。以上是关于如何访问 JArray 的元素（或迭代它们）的主要内容，如果未能解决你的问题，请参考以下文章