使用牛顿JSON从C＃中的反序列化JSON投射错误

Question

Unable to cast to int from deserialized json (dictionary object)

Here is the code:

Lets say you have dictionary object.

 Dictionary<string, object> dict = new Dictionary<string, object>();
 dict.Add("key", 1);

Now i serialize & deserialize it.

var serializedData = JsonConvert.SerializeObject(dict);
var deserializedData = JsonConvert.DeserializeObject<Dictionary<string, object>>(serializedData);

And getting error when i do this at runtime

int value = (int)deserializedData["key"];

Answer 1

我相信错误是JSON.NET假设您提到的数字是long（int64）类型而不是整数（int32），因此当您对对象进行装箱时，您无法直接将其装箱到int32，因此您需要进行更改您的代码

 int i = (int)(long) deserializedData["key"];

Answer 2

Your number is being serialized as a long (Int64). Try this:

int value = (int)(long)deserializedData["key"];

You have to unbox the long first and then convert it to an int after it has been unboxed. This makes more sense if you convert the above to separate statements:

object oValue = deserializedData["key"];
long longValue = (long)oValue;
int value = (int)longValue;

Answer 3

Because the type of deserializedData["key"] is Int64 (you'll see when you debug). You can't cast Int64 to int ( Int32 ) .

what you can do:

int value = System.Convert.ToInt32(deserializedData["key"]);