Proble with Custom property used to remove duplicates

NetBot

Hi all, I have a Gridview with with 4 columns....Brand,Category,Item,Stock The user wants that the for all items belonging to same Brand and category, the Brand and Category needs to be shown only once. For this i wrote the following code but it doesn`t seems to work...

Public Class GridItem
Dim _brand As String
Dim _cat As String

Public Sub GridItem()
    'Constructor
    \_brand = ""
    \_cat = ""
End Sub

Public Property Brand() As String
    Get
        Return \_brand
    End Get
    Set(ByVal value As String)
        \_brand = value
    End Set
End Property

Public Property Category() As String
    Get
        Return \_cat
    End Get
    Set(ByVal value As String)
        \_cat = value
    End Set
End Property

End Class

Sub ItemGrid_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs)

    If e.Row.RowType = DataControlRowType.DataRow Then
        Dim GI As New GridItem
        GI.Brand = e.Row.Cells(0).Text
        GI.Category = e.Row.Cells(1).Text
        If uniquearr.Contains(GI) Then
            e.Row.Cells(0).Text = ""
            e.Row.Cells(1).Text = ""
        Else
            uniquearr.Add(GI)
        End If
    End If
End Sub

uniquearr is declared global.Any help would be appreciated

gnjunge

I will answer in C#, if you don't understand tell me. Your problem is the following: (1) Contains uses Equals. (2)

GridItem g1 = new GridItem("bla", "bla");
GridItem g2 = new GridItem("bla", "bla");

if (g1.Equals(g2))
Response.Write("equal");
else
Response.Write("not equal");

This returns not equal. Why? If the GridItem does not implement an Equals function, it will check the equality of the HashCode.

Response.Write(g1.GetHashCode().ToString());
Response.Write(g2.GetHashCode().ToString());

Two different hashcodes. So how do we solve this? Add an Equals function to your GridItem:

public override bool Equals(object obj)
{
if (obj == null && this == null)
return true;
else if ( (obj == null && this != null ) || (obj != null && this == null))
return false;
else if (this.Brand == ((GridItem)obj).Brand && this.Category == ((GridItem)obj).Category)
return true;
else
return false;
}

This first checks if the object are null, and then checks if the contents of the objects are the same. Now the above equation of g1.Equals(g2), will return true.