Is there a quick way to say If notempty x = y else x = default in a Linq where query

Question

Is there a quick way to say

Where (data.x == (If notempty x = y else x = default))

Assuming the data being compared is both strings

Compare listitem.string with passed.string - if passed.string isnotempty, else passed.string equals default value.

in a Linq 'where` query.

Apologies that the question was really badly written.

... As per the comments updated ...

Answer 1

It really depends on the data type of x and y, but say they are strings:

Where (data.x == (!string.IsNullOrEmpty(y) ? y : "default"))

It's called the conditional operator.

Answer 2

Your original post could be interpreted to be this:

where (data.x ?? y) == y

Edit: I am now pretty sure this is what you were attempting. :)

Edit 2: This is the null-coalescing operator.

Edit 3: Whoever voted me down should post a reason. I interpreted the first post as: "If x is not empty, it should equal y, but it's ok to equal default(typeof y)." For reference types or nullable types, my post is correct.

Edit 4: Mine still could be the cleanest answer to his updated post. I keep reading it and it's still strangely worded. The (string.IsNullOrEmpty(y)) post is the other possibility.

Answer 3

Ok, with your clarifications to the original post, I think I see what you're getting at now.

Try the following clause (where data.x is your current element and y in the passed argument).

where y == (string.IsNullOrEmpty(y) ? "default" : data.x)

I do not believe it's possible to use the null coalescing operator here, since the variables you are comparing and returning are different.

Old Post:
If what is empty? I'm guessing you're referring to y.

For a generic type T, you could use the following clause:

where data.x == (y ?? DefaultValue<T>())

where DefaultValue is a generic function of T that returns a so-called "default" value.