How to get property value of a dynamic type where property name is in a variable in C#

Question

I am trying to get the value of a property of a dynamic object. The json string is parsed/deserialized into a dynamic object and then I want to access the property by name followed by the get value.

string json = "{\"key1\":\"value1\", \"key2\": \"value2\"}";
dynamic d = JObject.Parse(json);
Console.WriteLine("Key1 : " + d.key1); //value1

Above code works as expected but how to get the value using get property by name that is stored in a variable?

string jsonKey = "key2";
string json = "{\"key1\":\"value1\", \"key2\": \"value2\"}";
dynamic d = JObject.Parse(json);
var jsonValue = d.GetType().GetProperty(jsonKey).GetValue(d, null); //throws exception - Cannot perform runtime binding on a null reference
Console.WriteLine("jsonValue : " + jsonValue);

GetProperty(jsonKey) throws an exception Cannot perform runtime binding on a null reference

Or, if there is an alternative solution to this problem.

Answer 1

Does it have to use Reflection? You know that JObject.Parse will return JObject, so you can see what are the public methods/ properties. You can see that it does not expose public property of JSON, hence you cannot get the value.

There are several ways to get the value without Reflection:

string jsonKey = "key2";
string json = "{\"key1\":\"value1\", \"key2\": \"value2\"}";
dynamic d = JObject.Parse(json);
string jsonValue1 = d.Value<string>(jsonKey); // one way
string jsonValue2 = (string)d[jsonKey]; // another way

Answer 2

and like this:

   JsonValue jsonValue = JsonValue.Parse("{\"Width\": 800, \"Height\": 600,  \"Title\": \"View from 15th Floor\", \"IDs\": [116, 943, 234, 38793]}");
   double width = jsonValue.GetObject().GetNamedNumber("Width");
   double height = jsonValue.GetObject().GetNamedNumber("Height");
   string title = jsonValue.GetObject().GetNamedString("Title");
   JsonArray ids = jsonValue.GetObject().GetNamedArray("IDs");