C# .NET 3.5 - Performing list like operations on members of a list

Question

I have a field object and I create a list of fields:

class Field {

string objectName;
string objectType;
string fieldName;
string fieldValue;

//constructor...

}



List<Field> fieldList = new List<Field>();

Suppose I wanted to query this list to return a collection of distinct object names (to then be inserted into a checkedlistbox. How would I go about doing that?

I imagine some LINQ magic can manage this?

Answer 1

var q = from Field f select f.objectName; q = q.Distinct();

chkListbox.DataSource = q;

Answer 2

I want to query the list fieldList, not just the class field.

Answer 3

Sorry, I mistyped:

var q = from Field f in fileldList select f.objectName;

chkBoxList.DataSource = q.Distinct();

Answer 4

The expression should return a List of distinct object names from the list as defined. I converted it to a list since the docs for the CheckedListBox DataSource property indicated that it needs to implement IList or IListSource, not merely IEnumerable.

((ListControl)cbListBox).DataSource = fieldList.Select( f => f.objectName )
                                               .Distinct()
                                               .ToList() );

If accessing the checkedListBox as a ListControl doesn't give access to the DataSource (sometimes the docs lie), you could try:

cbListBox.Items.AddRange( fieldList.Select( f => f.objectName )
                                   .Distinct()
                                   .ToArray() );

Answer 5

Either of these work

Using var

1) var fieldNameCollection = from f in fieldList select f.FieldName; 2) Lambda syntax var fieldNameCollection = fieldList.Select(f => f.FieldName);

Alternately, instead of using var, you can also use IEnumerable fieldNameCollection = fieldList.Select(f => f.FieldName);

Answer 6

Brilliant.

I'd like to give everyone some points, but i'll have to go with tvanfosson's answer because he was the first to give a complete description.

Thanks all.

Answer 7

bleh, a problem.

My checkedlistbox does not have the datasource property? This is a winforms apps (not WPF if that makes a difference.)