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WPF Linq a collection to include or exclude items

Anonymous User236109-Dec-2013

I have 3 comboboxes that the user can select a value. On the SelectionChanged event of each combobox will filter out an observablecollection that would only populate another collection based on the values. The comboboxes contains a blank at the top for the user to select not to apply the filter on that column.

Is there a simple way to use linq to do this?

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Updated on 10-Dec-2013
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1 Answers

Anonymous User

Anonymous User

10-Dec-2013
Hi Jayprakash,

You xaml might be like this:

<ComboBox x:Name="cmb1"
SelectionChanged="Selector_OnSelectionChanged">
<ComboBox x:Name="cmb2" SelectionChanged="Selector_OnSelectionChanged">
<ComboBox x:Name="cmb3"
SelectionChanged="Selector_OnSelectionChanged">
 
And code of the handler:
var someCollection = new List<int>(); // some your
collection
// stubs
Expression<Func<int, bool>> predicate1 = (x)
=> true;
Expression<Func<int, bool>> predicate2 = (x)
=> true;
Expression<Func<int, bool>> predicate3 = (x)
=> true;
 
// real predicates
if (cmb1.SelectedIndex >= 0)
    predicate1 = (x)
=> x == (int)cmb1.SelectedValue;
if (cmb2.SelectedIndex >= 0)
    predicate2 = (x)
=> x == (int)cmb2.SelectedValue;
if (cmb3.SelectedIndex >= 0)
    predicate3 = (x)
=> x == (int)cmb3.SelectedValue;
 
// eval and out
lstBox.Items = someCollection.Where(predicate1)
                            
.Where(predicate2)
                             .Where(predicate3)
                            
.ToList();

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