How can i remove duplicate item from combobox with datasource?

2013-11-30

Question

_{Saturday, November 30, 2013 8:18 AM}

I have datatable name dt

With column1 column2

A 2

A 3

B 1

C 4

AND i add this table to be datasource of combobox1 and combobox1

combobox1.datasource = dt

combobox1.displaymember = "Column1"

combobox2.datasource = dt

combobox2.displaymember = "Column2"

So when combobox1 or combobox2 select change other one will be auto change to the same row of datasource

But item of combobox1 is duplicate i want to remove duplicate from combobox1 and when combobox1 select A , combobox2

item will be only 2 , 3. How can i do this?

Thanks

All replies (3)

_{Saturday, November 30, 2013 10:10 AM ✅Answered}

I would use some Enumerable funcions to get this work i.e.

comboBox1.Items.AddRange(dt.AsEnumerable().Select(i => i.ItemArray[0]).Distinct().ToArray());
comboBox2.Items.AddRange(dt.AsEnumerable().Select(i => i.ItemArray[1]).Distinct().ToArray());

_{Saturday, November 30, 2013 10:14 AM ✅Answered}

If you use a Datatable like you seems to do then use the overloaded function of the DataView which returns a distinct table. It is special made for your question. A sample is on this good MSDN page.

http://msdn.microsoft.com/en-us/library/wec2b2e6(v=vs.110).aspx

Success
Cor

_{Saturday, November 30, 2013 2:08 PM ✅Answered}

Solution 1 works off Column1, note use of DataTable.Copy and BindingSource.Filter. We could do away with BindingSources yet I see it makes sense to easily filter. I tend to use them for all Windows form projects.

Public Class frmDemo
    WithEvents bsData1 As New BindingSource
    WithEvents bsData2 As New BindingSource
    Private Sub frmDemo_Load(
        ByVal sender As System.Object,
        ByVal e As System.EventArgs) _
    Handles MyBase.Load

        Dim dt As New DataTable
        dt.Columns.Add(New DataColumn With
                       {
                           .ColumnName = "Column1",
                           .DataType = GetType(String)
                       }
                   )
        dt.Columns.Add(New DataColumn With
                       {
                           .ColumnName = "Column2",
                           .DataType = GetType(Integer)
                       }
                   )

        dt.Rows.Add(New Object() {"A", 2})
        dt.Rows.Add(New Object() {"A", 3})
        dt.Rows.Add(New Object() {"B", 1})
        dt.Rows.Add(New Object() {"C", 4})

        bsData1.DataSource = dt
        bsData2.DataSource = dt.Copy

        ComboBox1.DisplayMember = "Column1"
        ComboBox1.DataSource = bsData1

        ComboBox2.DisplayMember = "Column1"
        ComboBox2.DataSource = bsData2

    End Sub

    Private Sub bsData1_PositionChanged(
        ByVal sender As Object,
        ByVal e As System.EventArgs) _
    Handles bsData1.PositionChanged

        If bsData1.Current IsNot Nothing Then
            Dim Identifier As String =
                CType(bsData1.Current, DataRowView).Row.Field(Of String)("Column1")

            bsData2.Filter = "Column1 <> '" & Identifier & "'"

        End If

    End Sub

    Private Sub cmdRemoveFilter_Click(
        ByVal sender As System.Object,
        ByVal e As System.EventArgs) _
    Handles cmdRemoveFilter.Click

        bsData2.Filter = ""
    End Sub
End Class

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How can i remove duplicate item from combobox with datasource?

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