如何从 JSON 字符串中获取深度嵌套的属性?

How do I get a deeply-nested property from JSON string?(如何从 JSON 字符串中获取深度嵌套的属性?)

问题描述

如何使用 JSON.NET 从 JSON 中获取myThings"数组，如下所示?

How can I get the "myThings" array out of JSON that looks like the following using JSON.NET?

示例 1:

{
    "z": {
        "a": 1,
        "b": 2
    },
    "something": {
        "y": [1, 2],
        "somethingElse": {
            "1234": {
                "foo": "bar",
                "myThings": [{
                    "name": "bob",
                    "age": 3
                }, {
                    "name": "bob",
                    "age": 3
                }]
            }
        }
    }
}

示例 2:

{
    "z": {
        "a": 1,
        "b": 2
    },
    "something": {
        "y": [1, 2],
        "somethingElse": {
            "7890": {
                "foo": "bar"
            }
        }
    }
}

我遇到困难的几件事:

• 其中一个属性名称是一个不可预测的数字(1234"和7890")
• 有时myThings"数组不存在 - 在这种情况下，我想要的是 null 或空数组/集合

另一个对你有帮助的考虑:我确实有一个静态类来表示 myThings 数组中的东西，所以我理想的返回值是 IEnumerable<MyThing>

Another consideration in case it helps you: I do have a static class that represents the things inside of the myThings array, so my ideal return value would be IEnumerable<MyThing>

我的第一次尝试是使用 JsonConvert.DeserializeObject<dynamic>(json) 但我不知道如何处理我上面提到的问题.最后，我不需要整个 JSON 字符串的数据，只需要名为myThings"的内部数组.

My first attempt was to use JsonConvert.DeserializeObject<dynamic>(json) but I don't know how to handle the issues I mentioned above. In the end, I don't need the entire JSON string's worth of data, just that inside array named "myThings".

推荐答案

可以使用JToken.SelectTokens() 用于此目的.它允许使用通配符查询 JSON 并使用 JSONPath 语法进行递归搜索:

You can use JToken.SelectTokens() for this purpose. It allows for querying JSON using wildcards and recursive searches using the JSONPath syntax:

var root = JToken.Parse(json);
var myThings = root.SelectTokens("..myThings[*]").ToList();

这里".."是递归下降操作符，"myThings[*]"表示返回属性的所有数组项myThings".

Here ".." is the recursive descent operator and "myThings[*]" means to return all array items of the property "myThings".

原型小提琴.

如果 "myThings[*]" 的数组条目对应一些 POCO MyThing，则可以使用 JToken.ToObject() 查询后反序列化:

If the array entries of "myThings[*]" correspond to some POCO MyThing, you can use JToken.ToObject<T>() to deserialize them after querying:

    var myThings = root.SelectTokens("..myThings[*]").Select(t => t.ToObject<MyThing>()).ToList();

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