在 Json.net 中收到错误无法从 Newtonsoft.Json.Linq.JProperty 添加或删除项目

Assuming Values is a List<MyObject> and your MyObject class looks like this:

class MyObject
{
    public string Time { get; set; }
    public int Level { get; set; }
}

you can replace all that code with the following to get the result you want:

string json = File.ReadAllText(fileName);
Values = JToken.Parse(json)["docs"].ToObject<List<MyObject>>();

This works because Json.Net will ignore missing properties by default. Since the MyObject class does not contain an _id property to deserialize into, you don't need to jump through hoops trying to remove it from the JSON.

Explanation of why 100 didn't work

JToken.Remove()从其父对象中删除JToken.将JProperty从其父JObject中移除是合法的，或者说从JArray中移除子代JToken是合法的.但是，您不能从JProperty中删除该值.JProperty必须始终只有一个值.

当你要token["_id"]的时候，你得到的是JProperty中的value，叫做_id，而不是JProperty本身.因此，如果你try 调用Remove()，你会得到一个错误.要使其按您目前的方式工作，您需要使用Parent，如下所示:

if (inner["_id"] != null)
    inner["_id"].Parent.Remove();

This says "Find the property whose name is _id and give me the value. If it exists, get that value's parent (the property), and remove it from its parent (the containing JObject)."

A more straightforward way to do it is to use the Property() method to access the property directly. However, this method is only available on JObject, not JToken, so you would either need to change the declaration of inner to a JObject or cast it:

foreach (JObject inner in token["docs"].Children<JObject>())
{
    JProperty idProp = inner.Property("_id");
    if (idProp != null)
        idProp.Remove();
    ...
}

最后，如 comments 中所述，如果使用C#6或更高版本，可以使用null条件运算符将代码缩短一点:

    inner.Property("_id")?.Remove();