CODEWITHSUNDEEP
c#
Miguel Moura
Miguel Moura

Reputation: 39484

Check if an Object has something or not

I have the following property:

IDictionary<string, object> Values { get; }

The property has a few values having one of them the key "culture".

I tried to use that value and casting to a string:

String value = (String)data.Values["culture"] ?? defaultCulture;

This works when the item has some value but when it doesn't I get the error:

Unable to cast object of type 'System.Web.Mvc.UrlParameter' to type 'System.String'.

BTW, System.Web.Mvc.UrlParameter: http://msdn.microsoft.com/en-us/library/system.web.mvc.urlparameter%28v=vs.108%29.aspx

In the debugger data.Values["culture"] has the value {}. I tested and:

var test_1 = data.Values["culture"] == null; // returns false

var test_2 = data.Values["culture"].ToString() == null; // returns false

How do I check if data.Values["culture"] has something in it or not?

Upvotes: 0

Views: 184

Answers (4)

svick
svick

Reputation: 244998

If you want to get the string if it indeed is a string and a default value otherwise, you can test the type of the valuer using as. Something like:

(data.Values["culture"] as string) ?? defaultCulture

Upvotes: 1

M.Shahin
M.Shahin

Reputation: 41

did you use this? 

string.IsNullOrWhiteSpace(somestring)

Upvotes: 0

mayabelle
mayabelle

Reputation: 10014

Try this:

String value = (String) (data.Values["culture"] ?? defaultCulture);

The idea is to check for null before trying to cast.

Upvotes: 0

John Saunders
John Saunders

Reputation: 161831

Apparently, you are storing a UrlParameter in that dictionary entry. If you want to get a string out, you will need to use ToString().

The exact expression to use will depend on the type of defaultCulture. If it is a string, then

String value = data.Values["culture"] == null ? defaultCulture : data.Values["culture"].ToString();

if it is a UrlParameter, then

String value = (data.Values["culture"] ?? defaultCulture).ToString();

Upvotes: 3

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