VB.NET

Check if list already Contains() object with equal key

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Join Date: May 2009

Posts: 4

Reputation: HalloJoe is an unknown quantity at this point

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HalloJoe

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Check if list already Contains() object with equal key

May 3rd, 2009

Hi all!

I need to check if an object with equal property value(CustomObject.Key) exist in my custom list

In a List(Of String) i would do it like this

 Help with Code Tags 
 VB.NET Syntax (Toggle Plain Text) 
    Public Class StringList
        Inherits List(Of String)
 
        Public Overloads Sub Add(ByVal s As String)
            If Not Me.Contains(s) Then
                MyBase.Add(s)
            End If
        End Sub
 
    End Class
    Public Class StringList
        Inherits List(Of String)

        Public Overloads Sub Add(ByVal s As String)
            If Not Me.Contains(s) Then
                MyBase.Add(s)
            End If
        End Sub

    End Class

How can i do the same Contains check on my CustomObject.Key ?

 Help with Code Tags 
 VB.NET Syntax (Toggle Plain Text) 
    Public Class CustomList
        Inherits List(Of CustomObject)
 
        Public Overloads Sub Add(ByVal o As CustomObject)
            ' If  Not Me.Contains[an object with the same Key as the one im trying to add]?
            MyBase.Add(o)
            ' End If
        End Sub
 
    End Class
 
    Public Class CustomObject
        Public Key As String
        Public Num As Integer
        Public Ok As Boolean
    End Class
    Public Class CustomList
        Inherits List(Of CustomObject)

        Public Overloads Sub Add(ByVal o As CustomObject)
            ' If  Not Me.Contains[an object with the same Key as the one im trying to add]?
            MyBase.Add(o)
            ' End If
        End Sub

    End Class

    Public Class CustomObject
        Public Key As String
        Public Num As Integer
        Public Ok As Boolean
    End Class

Hope you can help

O_o

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Join Date: May 2009

Posts: 4

Reputation: HalloJoe is an unknown quantity at this point

Solved Threads: 0

HalloJoe

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Re: Check if list already Contains() object with equal key

May 3rd, 2009

Found it out - pretty simple

I created a class that implements IEqualityComparer:

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 VB.NET Syntax (Toggle Plain Text) 
Public Class CustomEqualityComparer
    Implements IEqualityComparer(Of CustomObject)
 
    Public Function Equals1(ByVal x As CustomObject, ByVal y As CustomObject) As Boolean Implements System.Collections.Generic.IEqualityComparer(Of CustomObject).Equals
         Return String.Equals(x.key.Trim, y.key.Trim)
    End Function
 
    Public Function GetHashCode1(ByVal obj As RssItem) As Integer Implements System.Collections.Generic.IEqualityComparer(Of CustomObject).GetHashCode
        Return obj.ToString().ToLower().GetHashCode()
    End Function
 
End Class
Public Class CustomEqualityComparer
    Implements IEqualityComparer(Of CustomObject)

    Public Function Equals1(ByVal x As CustomObject, ByVal y As CustomObject) As Boolean Implements System.Collections.Generic.IEqualityComparer(Of CustomObject).Equals
         Return String.Equals(x.key.Trim, y.key.Trim)
    End Function

    Public Function GetHashCode1(ByVal obj As RssItem) As Integer Implements System.Collections.Generic.IEqualityComparer(Of CustomObject).GetHashCode
        Return obj.ToString().ToLower().GetHashCode()
    End Function

End Class

Then i use the comparer like this:

 Help with Code Tags 
 VB.NET Syntax (Toggle Plain Text) 
Public Class CustomList
    Inherit List(Of CustomObject)
 
        Public Overloads Sub Add(ByVal o As CustomObject)
                If Not Me.Contains(o, New CustomObjectEqualityComparer()) Then _
                        MyBase.Add(o)
        End Sub
 
End Class
Public Class CustomList
    Inherit List(Of CustomObject)

        Public Overloads Sub Add(ByVal o As CustomObject)
                If Not Me.Contains(o, New CustomObjectEqualityComparer()) Then _
                        MyBase.Add(o)
        End Sub

End Class

O_o

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Join Date: Apr 2009

Posts: 2

Reputation: tennisace24 is an unknown quantity at this point

Solved Threads: 1

tennisace24 tennisace24 is offline

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Re: Check if list already Contains() object with equal key

May 3rd, 2009

I have a search in my program for names form a database and i wnat it to show all the information form name row in a datagrid but its only showing the name and not the information like address so how do i make show all information from that name row! From my query? Here is the code:

Public Class Form1

Private Sub DisplaySearchResults(ByVal objectname As String, ByVal FieldName As String, ByVal Searchdata As String)

Dim SQL_String As String

dbConnection = New OleDb.OleDbConnection(ConnectString)
dbAdapter = New OleDb.OleDbDataAdapter
dtSearch = New DataTable()

SQL_String = "select * from " & objectname & " where " & FieldName & "='" & Searchdata & "'" 'missing equals sign
dbAdapter = New OleDb.OleDbDataAdapter(SQL_String, ConnectString)
dbConnection.Open()
dbAdapter.Fill(dtSearch)
grdSearch.DataSource = dtSearch
dbConnection.Close()

End Sub

Private Sub btnWards_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnWards.Click
grdHospital.DataSource = DisplayData("tblWards")

End Sub

Private Sub btnPatients_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPatients.Click
grdHospital.DataSource = DisplayData("tblPatients")
End Sub

Private Sub btnPatientsWards_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPatientsWards.Click
grdHospital.DataSource = DisplayData("qryPatientsByWard")
End Sub

Private Sub btnWardNameSearch_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnWardNameSearch.Click

Dim objectname As String
Dim Fieldname As String
Dim Searchdata As String

'objectname = "tblWards" 'missing s at end of tablename
objectname = "qryPatientsByWard" 'to get the patient name you need to use this query not the wards table
Fieldname = "WardName"
Searchdata = cboWardName.Text
DisplaySearchResults(objectname, Fieldname, Searchdata)
End Sub

Private Sub btnPatientSearch_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPatientSearch.Click
Dim ObjectName As String
Dim FieldName As String
Dim SearchData As String

ObjectName = "tblPatients"
FieldName = "PatientName"
SearchData = txtSearch.Text
DisplaySearchResults(ObjectName, FieldName, SearchData)

End Sub

Private Sub btnPatientAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPatientAdd.Click
Dim SQL_Insert As String
SQL_Insert = "INSERT INTO tblPatients( PatientName, WardID )" & "VALUES ( '" & txtPatientName.Text & "', " & (cboWardName.SelectedIndex + 1) & ") "
ExecuteSQL(SQL_Insert)
grdHospital.DataSource = DisplayData("tblPatients")
End Sub

Private Sub btnDelete_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDelete.Click
Dim intPatientID As Integer

If (IsNumeric(txtDelPatient.Text)) Then
intPatientID = CInt(txtDelPatient.Text)

Dim intUpdated As Integer

intUpdated = ExecuteSQL("DELETE FROM tblPatients WHERE PatientID = " & intPatientID)

If intUpdated > 0 Then
grdHospital.DataSource = DisplayData("tblPatients")
MsgBox("Patient Succesfully Deleted", MsgBoxStyle.Information, "Deleted")
Else
MsgBox("Patient not found in Table", MsgBoxStyle.Critical, "Error")
End If
Else
MsgBox("Invalid Patient ID", MsgBoxStyle.Critical, "Error")
End If
End Sub
End Class