How to Get a Specific Value from an Object that is a Dictionary?

Question

I'll show my question with an example:

ChromeDriver chrome = new ChromeDriver();
chrome.Capabilities.GetCapability("chrome");

Returns an object which is of type Dictionary<string, object>. Inside this object there's a key userDataDir whose value I need.

Do I have to cast the object to a dictionary first or can I do some one-liner like:

chrome.Capabilities.GetCapability("chrome").GetType().GetProperty("userDataDir").GetValue()

The line above isn't compiled just to clarify.

Is the value within the dictionary itself a dictionary whose key you want to access? — MakePeaceGreatAgain, Feb 04 '16 at 15:16
have you even tried a google search perhaps `how to retrieve values from a Dictionary` ? http://stackoverflow.com/questions/378465/retrieving-dictionary-value-best-practices — MethodMan, Feb 04 '16 at 15:16
Are you saying the return type of `GetCapability` is `Dictionary` or is the return type `object` and the specific object you are getting is a `Dictionary` that you need to cast first? — juharr, Feb 04 '16 at 15:19
@HimBromBeere No, the object is the dictionary that has the key. — Moshisho, Feb 04 '16 at 15:21
@juharr The return type is object, the question is if I must cast first. — Moshisho, Feb 04 '16 at 15:23
@Moshisho Yes, the best course of action here is definitely to cast. — juharr, Feb 04 '16 at 15:24

score 1 · Answer 1 · answered Feb 04 '16 at 15:15

If the returntype of chrome.Capabilities.GetCapability("chrome"); is Dictionary<string, object>

You can do as following, by casting the returned object to a Dictionary :

var capability = (Dictionary<string, object>)chrome.Capabilities.GetCapability("chrome");
var userDataDir = capability["userDataDir"];

juharr · Accepted Answer · 2016-02-04T15:23:41.863

You could do the cast on one line with as

var userDataDir = (chrome.Capabilities.GetCapability("chrome") as Dictionary<string, object>)["userDataDir"];

Of course this opens you up to possible null reference exceptions. With C# 6 you could use the null-conditional to mitigate that.

var userDataDir = (chrome.Capabilities.GetCapability("chrome") as Dictionary<string, object>)?["userDataDir"];

But then you would not know if null was a value in the dictionary or if it was null because the cast failed. The best bet is just to do this in multiple lines.

var dic = chrome.Capabilities.GetCapability("chrome") as Dictionary<string, object>;
if(dic == null)
{
    // The capability isn't a dictionary.
}
else
{
    var userDataDir = dic["userDataDir"];
}

Actually in my case it can't be null, because that will indicate that the functionality is wrong at the first place. — Moshisho, Feb 04 '16 at 15:47

How to Get a Specific Value from an Object that is a Dictionary?

2 Answers2