I'm wondering how the filters in RadGridView work. How do they check for equality?
After some experimentation it seems that they check for "referential equality" (is that what is it called??), that is the filter checks if the rows have exactly the same object as the filter. So even if a column shows a custom type of mine and I have implemented the Equals() method, it won't matter.
Lets say I
have a custom type representing a customer:
public
class
Customer : IComparable
{
public
int
Id {
get
;
set
; }
public
string
Name {
get
;
set
; }
public
Customer(
int
id,
string
name)
{
Id = id;
Name = name;
}
public
override
string
ToString()
{
return
Name;
}
public
virtual
int
CompareTo(
object
obj)
{
Customer otherCustomer = obj
as
Customer;
if
(otherCustomer !=
null
)
{
return
this
.Id.CompareTo(otherCustomer.Id);
}
else
{
throw
new
ArgumentException(
"Can only compare to other Customer instances."
);
}
}
public
override
bool
Equals(
object
obj)
{
if
(obj.GetType() ==
typeof
(Customer))
{
Customer otherCustomer = (Customer) obj;
return
otherCustomer.Name == Name;
}
else
{
return
false
;
}
}
}
I'm using MVVM and each row displayed in the gridview has a viewmodel. This viewmodel has the following code:
private
Customer _contact;
public
Customer Contact
{
get
{
return
_contact;
}
set
{
if
(value != _contact)
{
_contact = value;
OnPropertyChanged(
"Contact"
);
}
}
}
public
BindingList<Customer> AllContacts {
get
;
private
set
;}
The row-viewmodel has a property called "Contact" that is of my custom type. It also has a BindingList of the same type that will contain all available contact/customers.
And in my XAML I have this code:
<
tgv:RadGridView
ItemsSource
=
"{Binding Path=MyData, Mode=OneWay}"
>
<
tgv:RadGridView.Columns
>
<!-- Columns excluded for brevity... -->
<
tgv:GridViewDataColumn
Name
=
"ContactColumn"
Header
=
"Contact"
DataMemberBinding
=
"{Binding Path=Contact}"
>
<
tgv:GridViewDataColumn.CellTemplate
>
<
DataTemplate
>
<
TextBlock
Text
=
"{Binding Path=Contact.Name, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}"
/>
</
DataTemplate
>
</
tgv:GridViewDataColumn.CellTemplate
>
<
tgv:GridViewDataColumn.CellEditTemplate
>
<
DataTemplate
>
<
ti:RadComboBox
ItemsSource
=
"{Binding Path=AllContacts, Mode=OneTime}"
DisplayMemberPath
=
"Name"
SelectedItem
=
"{Binding Path=Contact, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
/>
</
DataTemplate
>
</
tgv:GridViewDataColumn.CellEditTemplate
>
</
tgv:GridViewDataColumn
>
</
tgv:RadGridView.Columns
>
</
tgv:RadGridView
>
As you can see the column that shows the contact binds to the property Contact on the row-viewmodel. In the cell edit template there's a ComboBox that allows the user to choose one contact from the list with all contacts.
"MyData" that the gridview is bound to is a QueryableCollectionView that has all the rows (row-viewmodels) that are to be displayed. It is created something like this:
RadObservableCollection<DataRowViewModel> myDataRows =
new
RadObservableCollection<DataRowViewModel>();
//...Here would be some code to fill myDataRows with row-viewmodels...
MyData =
new
QueryableCollectionView(myDataRows);
All this works fine.
Now I want to apply filtering on that column by code. Let's say that there are ten available customers. If I open the filter popup on the gridview all ten are displayed in the list of checkboxes where you can specify which ones to show. These are the "distict filters". To apply distinct filters in code behind I would do something like this:
MyData.FilterDescriptors.Clear(); //Clear old filters
ColumnFilterDescriptor cfd =
new
ColumnFilterDescriptor(ContactColumn);
FilterDescriptor fd =
new
FilterDescriptor();
fd.Member =
"Contact"
;
fd.Operator = FilterOperator.IsEqualTo;
fd.Value =
new
Customer(1,
"David"
);
fd.IsCaseSensitive =
true
;
cfd.DistinctFilter.FilterDescriptors.Add(fd);
MyData.FilterDescriptors.Add(cfd);
When I run this I see that a filter is applied, but all my rows are removed by the filter, even those that has Id=1 and Name=David.
I have tried a different model where I don't create a new Customer and put in the Value of the filter but instead put an instance of Customer that is actually in the list AllCustomers. When I do this it works fine. The filter removes all rows except those who has that specific customer (David) as customer. This leads me to think that the filter checks equality by checking "referential equality" and does not use the Equals method.
Am I right in this assumption or is it something else I'm missing?