I just need a little confirmation ...
I'm filling my combobox like so:
myCombo.Items.Add(new ComboBoxInt32Data("Red", 0));
myCombo.Items.Add(new ComboBoxInt32Data("Green", 1));
myCombo.Items.Add(new ComboBoxInt32Data("Yellow", 2));
myCombo.Items.Add(new ComboBoxInt32Data("Blue", 3));
Now, when I'm retrieving values from the database table, I have just the integer value.
My overriden Equals looks exactly as how msdn suggests :
public override bool Equals(object obj)
{
if (obj == null)
{
return false;
}
ComboBoxInt32Data data = obj as ComboBoxInt32Data;
if ((object)data == null)
{
return false;
}
return (m_Name.ToUpper() == data.Name.ToUpper() && m_Value == data.Value);
}
But, as I mentioned, I have just the value. I don't want to have to go and do the following:
Int32 DatabaseValue = SomeFunctionThatRetrivedMeThisIntValueFromDB();
string TheValueName = SomeFunctionThatDoesALookUpToGetTheName(DatabaseValue);
myCombo.SelectedIndex = myCombo.Items.IndexOf(new ComboBoxInt32Data(TheValueName, DatabaseValue));
I'd rather just do the following:
myCombo.SelectedIndex = myCombo.Items.IndexOf(SomeFunctionThatRetrivedMeThisIntValueFromDB());
So, my confirmation is, is it OK (as in, is it an acceptable best practice) to do the following in my Equals (look for 'added this'):
public override bool Equals(object obj)
{
if (obj == null)
{
return false;
}
// added this
if (obj is Int32)
{
Int32 value = (Int32)obj;
return m_Value == value;
}
ComboBoxInt32Data data = obj as ComboBoxInt32Data;
if ((object)data == null)
{
return false;
}
return (m_Name.ToUpper() == data.Name.ToUpper() && m_Value == data.Value);
}
Thanks!
You don't need to override Equal
and GetHashCode
, the easy way is to cast to ComboBoxInt32Data
and use LINQ to select item:
myCombo.SelectedItem = myCombo.Items.Cast<ComboBoxInt32Data>()
.SingleOrDefault(item => item.Value == databaseValue);
I'm not sure if I'm just misunderstanding your need, or if I'm really seeing what I think I'm seeing, but I think I can simplify your solution quite a bit. Let's take a very simple example - I have a table named FooTypes
and it contains data like this:
Id Name Order
-----------------------------------
1 Type 1 1
2 Type 2 2
3 Type 3 4
4 Type 4 3
And now I want to load a combo box with that data so I'm going to do something like this**:
var conn = new SqlConnection("some connection string");
var da = new SqlDataAdapter("SELECT Id, Name FROM FooTypes ORDER BY Order", conn);
var dt = new DataTable();
da.Fill(dt);
comboBox.ValueMember = "Id";
comboBox.DisplayMember = "Name";
comboBox.DataSource = dt;
comboBox.SelectedValue = SomeFunctionThatRetrivedMeThisIntValueFromDB();
** Bear in mind this is an example so you may grab the connection and stuff from somewhere else.
Try the following:
var indexToSelect = SomeFunctionThatRetrievedMeThisIntValueFromDB();
var selectedItem = myCombo.Items
.Cast<ComboBoxInt32Data>()
.FirstOrDefault(item => item.Value == indexToSelect);
if (selectedItem != null)
{
myCombo.SelectedItem = selectedItem;
}
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