Is there a null handler to string method at c#

Question

I am able to assign a variable like below:

if (Session["myVariable"] != null)
{
    string variAble = Session["myVariable"].ToString();
}

Is there a method which checks whether an object is null or not and then assign if it is not null?

ye but it does not handle other objects such as session. if the object you are comparing is string it works. — Furkan Gözükara
– Furkan Gözükara, Commented Jan 17, 2013 at 22:30
so if the value is null you dont want to assign the variable at all, or provide a default value? could you write some puedo code on how you want this to work — sa_ddam213
– sa_ddam213, Commented Jan 17, 2013 at 22:32
@sa_ddam213 if you don't make that null check comparison your application would throw error if that session is null. so i am looking for a method that would do session null check and if not null assign to string like string.IsNullOrEmpty — Furkan Gözükara
– Furkan Gözükara, Commented Jan 17, 2013 at 22:36

Ofer Zelig · Accepted Answer · 2013-01-17 22:46:47Z

5

string variAble = Session["myVariable"] ?? "";

EDIT A slightly more robust form, as suggested by @hatchet, is:

string variAble = (Session["myVariable"] ?? "").ToString();

edited Jan 17, 2013 at 22:46

answered Jan 17, 2013 at 22:30

Ofer Zelig

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4 Comments

hatchet - done with SOverflow Over a year ago

If he needed to do the ToString, then = (Session["myVariable"] ?? "").ToString();

hatchet - done with SOverflow Over a year ago

@ReedCopsey - that can be handled with the slight modification in my comment above.

hatchet - done with SOverflow Over a year ago

@ReedCopsey I thought if Session[] returns an object (or boxed value type), then that would work since all object descendants have ToString.

Reed Copsey Over a year ago

@hatchet but it returns it as a string, not an int, etc. That was what I was trying to say.

Reed Copsey · Accepted Answer · 2013-01-17 22:30:38Z

2

While this isn't anything new, you can use the conditional operator to potentially simplify this:

string variable = Session["myVariable"] != null ? Session["myVariable"].ToString() : "Fallback";

answered Jan 17, 2013 at 22:30

Reed Copsey

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1 Comment

Reed Copsey Over a year ago

@HamletHakobyan Nope - always been there.

TheEvilPenguin · Accepted Answer · 2013-01-17 22:36:50Z

2

You could write an extension method, as those still work with null objects.

public static class StringExtensions
{
    public static String ToNullString(this object o)
    {
        return o == null ? "" : o.ToString();
    }
}

I would consider it poor form though - it'll be confusing to whoever will be supporting the code after you, or even to you a few months down the track. It's probably better to just do the null check.

answered Jan 17, 2013 at 22:36

TheEvilPenguin

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10 Comments

Furkan Gözükara Over a year ago

but i suppose this would not be entire application wide am i incorrect ? can i define an extension method for entire asp.net website ?

sa_ddam213 Over a year ago

@TheEvilPenguin, StringExtensions will have to be a static class

TheEvilPenguin Over a year ago

@MonsterMMORPG As long as you include the namespace the class is in, you'll be able to use it anywhere that references the assembly it's in

TheEvilPenguin Over a year ago

@sa_ddam213 Thanks. That's what I get for not compiling code before I post it

Furkan Gözükara Over a year ago

@TheEvilPenguin instead of me to go each existing page and add reference can i add it globally somehow ?

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