What does an Empty IQueryable return as when Empty?

Question

I am in need of determining whether an IQueryable Method returns with Data, or "Empty" when applying it to a DataSource of a RadGrid like so:

RadGrid.DataSource = Method(x);

        if (Method(x) == yyy)
        {
            button.Enabled = true;
        }
        else
        {
            button.Enabled = false;
        }

I have tried using "null" in place of the "yyy" but with no success. When stepping through the code, the IQueryable Method returns as "Empty" but I am unsure of how to verify that using an If statement.

What does an IQueryable Method return as if it returns as Empty, and how can I verify that using an If Statement?

Answer 1

You can use Any() to check to see if there are any elements in the IQueryable:

RadGrid.DataSource = Method(x);

if (Method(x).Any())
{
    button.Enabled = true;
}
else
{
    button.Enabled = false;
}

(Or, alternatively, the shorter version:)

button.Enabled = Method(x).Any();

Answer 2

You want to use IQueryable.Any.

bool empty = !queryable.Any();
if(empty) {
    // something
}