Question

The best solution I could find (anywhere) to get results from an SQL Query into a local variable was to use a NULL List<dynamic> or IEnumerable<dynamic> variable declaration.

Creating the variable by doing something like:

@{
    IEnumerable<dynamic> myVariable = null;
}

The variable can then get a value from a database query like:

@{
    try
    {
        Database db = Database.Open("name"); // name of connectionString configured in web.config
        string myQuery = "EXEC dbo.Get_Results @Param1=@0, @Param2=@1";
        myVariable = db.Query(myQuery, @Param1, @Param2);
        db.Close();
        db.Dispose();
    }
    catch (Exception ex)
    {
        // Do something
    }

Which allows me to do something like the following:

@if(myVariable != null)
{
    foreach (var row in myVariable)
    {
        // Do something
    }
}

This is working perfectly, but what I am still curious is how to do the same using List<dynamic>, as an alternative to using IEnumerable<dynamic> the way I am using it.

What is the List<dynamic> equivalent solution that I am using for IEnumerable<dynamic>?

I know my question itself is very simple, but it took me a long time to get past trying to solve can’t implicitly convert errors when I tried to create a Class that could receive the results from db.Query(commandText) into a pre-declared variable. So I thought I should provide more detail in case this helps someone else trying to figure out the same or similar. I found my solution on the IEnumerable<dynamic> in unrelated topic which opened my eyes to much simpler solution to problem I was trying to solve.

Answer 1

Enumerable.Empty<string>() is not null. It is an empty sequence of strings. Note, for example, that the following code prints “false”:

var sequence = Enumerable.Empty<string>();
Console.WriteLine(sequence == null);

You probably want to create a new (empty) list:

List<dynamic> x = new List<dynamic>();

or, if you really need the list variable to hold a null reference:

List<dynamic> x = null;