Nullable bool or bool with default value in action?

Question

Perhaps a small question but im curious.

What is favored?

In a controllers action, when passing arguments, when and how should they be used?

public ActionResult Action(bool aBool = false)

or

public ActionResult Action(bool? aNullableBool)

I tend to use defualt-value as its a bit more clear and eassier to check, but am i thinking wrong?

Answer 1

The two are not equivalent. In the first example, the caller must specify true or false , if he does not, false is used.

In the second line, the caller may provide true , or false , or null . You will need to decide how to handle null . That's a third value that you can get. Plus the caller can not omit it. He needs to pass a value.

Answer 2

The .HasValue property of nullable variables can be quite handy sometimes. Having a nullable bool is like having a bool in a bool. Take Chuong Les example with the database, when you read a cell you may want to check that the cell actually holds a value before continuing (and ending up with an error further down the line).

Instead of having to make sure that isn't the case before reading the cell you can use a nullable variable and use if (aNullableBool.HasValue) to make sure you have a value before continuing.

That beeing said, unless you run the risk of the variable getting the value null you should use a default value.

Answer 3

我认为Route配置中的默认值是最好的。

Answer 4

It depends of the role of your bool.

If you want to have a default value or not (default behavior + just one other behavior), so just 2 behavior of this method.

If you want to have a third behavior as a default behavior, you will need to use a nullable bool.

So think about the needs of your method and choose accordingly.