59163

How can I filter a DataSource before applying it to a ListView

Question:

I have an Entity datasource, which I need to filter before passing it to the ListView. Here is the unfiltered version (works great):

DataContext db = new DataContext(); ListView1.DataSource = db.Cars; ListView1.DataBind();

I'm trying to understand how to select only the Cars that are blue (a field/property/row in the database), and pass just those Cars to the ListView. I've been trying variations on this:

String selectedColor = "blue"; DataContext db = new DataContext(); ListView1.DataSource = db.Cars.Any(m => m.Cars.color == selectedColor); ListView1.DataBind();

Answer1:

Shouldn't this be more like,

ListView1.DataSource = db.Cars.Where(car => car.Color == selectedColor);

Your db.Cars.Any(m => m.Cars.color == selectedColor) [Correction: should be m.Color instead of m.Cars.Color if you wanted to use it by the way] statement will return true if in your Cars collection there's at least one car with color value as that of the selectedColor.

Answer2:

Any() Returns a bool. You need Where()

Answer3:

I would also wrap your context using a using statement. This should take care of your context's disposal automatically.

String selectedColor = "blue"; using(DataContext db = new DataContext()) { ListView1.DataSource = db.Cars.Where(m => m.Cars.color == selectedColor); ListView1.DataBind(); }

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