Binding to an enumeration

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  • Nathan
    #1

    Binding to an enumeration

    I'd like to use an enumeration as a datasource for a drop-down box. Is there
    a way to do this?
    Tags: None
    • Jay B. Harlow [MVP - Outlook]
      #2
      Re: Binding to an enumeration

      Nathan,
      Have you tried something like:

      Public Enum SomeEnum
      Value1 = 1
      Value2 = 2
      End Enum

      Dim list As Array = [Enum].GetValues(GetT ype(SomeEnum))

      Then bind the above list variable?

      Some people bind to the names, via [Enum].GetNames, as opposed to the
      values. I prefer using the values as above In Windows Forms as the
      ComboBox.Select edValue is the enum value rather then a string... In Web
      Forms I don't see an advantage to using the values, but then again I have
      not bound to enums in web forms...

      --
      Hope this helps
      Jay B. Harlow [MVP - Outlook]
      ..NET Application Architect, Enthusiast, & Evangelist
      T.S. Bradley - http://www.tsbradley.net


      "Nathan" <Nathan@discuss ions.microsoft. com> wrote in message
      news:CD812C76-D8B2-49AE-8194-6D5AD2095068@mi crosoft.com...
      | I'd like to use an enumeration as a datasource for a drop-down box. Is
      there
      | a way to do this?


        Comment

        • David Lee Conley
          #3
          Re: Binding to an enumeration

          Nathan,

          What I've pasted below is from the VS2005 Help documentation. It doesn't
          specify for which version of .NET it's for, so I can't guarantee it'll work
          for all versions.

          Dave
          _______________ _______________ _______________ ____________
          The following code example demonstrates how to bind a collection of objects
          to a DataGridView control so that each object displays as a separate row.
          This example also illustrates how to display a property with an enumeration
          type in a DataGridViewCom boBoxColumn so that the combo box drop-down list
          contains the enumeration values.

          This example requires:

          a.. References to the System and System.Windows. Forms assemblies.

          Imports System.Windows. Forms
          Imports System.Collecti ons.Generic

          Public Enum Title
          King
          Sir
          End Enum

          Public Class EnumsAndComboBo x
          Inherits Form

          Private flow As New FlowLayoutPanel ()
          Private WithEvents checkForChange As Button = New Button()
          Private knights As List(Of Knight)
          Private dataGridView1 As New DataGridView()

          Public Sub New()
          MyBase.New()
          SetupForm()
          SetupGrid()
          End Sub

          Private Sub SetupForm()
          AutoSize = True
          End Sub

          Private Sub SetupGrid()
          knights = New List(Of Knight)
          knights.Add(New Knight(Title.Ki ng, "Uther", True))
          knights.Add(New Knight(Title.Ki ng, "Arthur", True))
          knights.Add(New Knight(Title.Si r, "Mordred", False))
          knights.Add(New Knight(Title.Si r, "Gawain", True))
          knights.Add(New Knight(Title.Si r, "Galahad", True))

          ' Initialize the DataGridView.
          dataGridView1.A utoGenerateColu mns = False
          dataGridView1.A utoSize = True
          dataGridView1.D ataSource = knights

          dataGridView1.C olumns.Add(Crea teComboBoxWithE nums())

          ' Initialize and add a text box column.
          Dim column As DataGridViewCol umn = _
          New DataGridViewTex tBoxColumn()
          column.DataProp ertyName = "Name"
          column.Name = "Knight"
          dataGridView1.C olumns.Add(colu mn)

          ' Initialize and add a check box column.
          column = New DataGridViewChe ckBoxColumn()
          column.DataProp ertyName = "GoodGuy"
          column.Name = "Good"
          dataGridView1.C olumns.Add(colu mn)

          ' Initialize the form.
          Controls.Add(da taGridView1)
          Me.AutoSize = True
          Me.Text = "DataGridVi ew object binding demo"
          End Sub

          Private Function CreateComboBoxW ithEnums() As DataGridViewCom boBoxColumn
          Dim combo As New DataGridViewCom boBoxColumn()
          combo.DataSourc e = [Enum].GetValues(GetT ype(Title))
          combo.DataPrope rtyName = "Title"
          combo.Name = "Title"
          Return combo
          End Function

          #Region "business object"
          Private Class Knight
          Private hisName As String
          Private good As Boolean
          Private hisTitle As Title

          Public Sub New(ByVal title As Title, ByVal name As String, _
          ByVal good As Boolean)

          hisTitle = title
          hisName = name
          Me.good = good
          End Sub

          Public Property Name() As String
          Get
          Return hisName
          End Get

          Set(ByVal Value As String)
          hisName = Value
          End Set
          End Property

          Public Property GoodGuy() As Boolean
          Get
          Return good
          End Get
          Set(ByVal Value As Boolean)
          good = Value
          End Set
          End Property

          Public Property Title() As Title
          Get
          Return hisTitle
          End Get
          Set(ByVal Value As Title)
          hisTitle = Value
          End Set
          End Property
          End Class
          #End Region

          Public Shared Sub Main()
          Application.Run (New EnumsAndComboBo x())
          End Sub

          End Class

          "Nathan" <Nathan@discuss ions.microsoft. com> wrote in message
          news:CD812C76-D8B2-49AE-8194-6D5AD2095068@mi crosoft.com...[color=blue]
          > I'd like to use an enumeration as a datasource for a drop-down box. Is
          > there
          > a way to do this?[/color]


            Comment

            • Mythran
              #4
              Re: Binding to an enumeration


              "Nathan" <Nathan@discuss ions.microsoft. com> wrote in message
              news:CD812C76-D8B2-49AE-8194-6D5AD2095068@mi crosoft.com...[color=blue]
              > I'd like to use an enumeration as a datasource for a drop-down box. Is
              > there
              > a way to do this?[/color]

              What we have done is created a method that takes a drop-down listbox
              control, enumeration type, and default value. For each enum value, we added
              a Description attribute that describes the value. Then instead of
              displaying the enumeration names/values, we display (using reflection) the
              values of the DescriptionAttr ibute for each enumeration value. This way,
              each item displayed in the drop down is displayed in a more descriptive
              way...

              HTH,
              Mythran

                Comment

                • Herfried K. Wagner [MVP]
                  #5
                  Re: Binding to an enumeration

                  "Nathan" <Nathan@discuss ions.microsoft. com> schrieb:[color=blue]
                  > I'd like to use an enumeration as a datasource for a drop-down box. Is
                  > there
                  > a way to do this?[/color]

                  See:

                  <URL:http://groups.google.d e/group/microsoft.publi c.dotnet.langua ges.vb/msg/6ded56f06760df6 9>

                  --
                  M S Herfried K. Wagner
                  M V P <URL:http://dotnet.mvps.org/>
                  V B <URL:http://classicvb.org/petition/>

                    Comment

                    • Dennis
                      #6
                      RE: Binding to an enumeration

                      The following code binds an enum to a combo-box and then retrieves the Enum
                      that is selected in the combo-box:

                      dim mySelectedEnum as myEnum

                      'Display the Enum names in the combo box
                      myComboBox.Data Source = [Enum].GetNames(GetTy pe(myEnum))

                      'Get the selected Enum
                      mySelectedEnum = CType([Enum].Parse(GetType( myEnum), _
                      myComboBox.Sele ctedItem.ToStri ng), myEnum)

                      Hope this helps.
                      --
                      Dennis in Houston


                      "Nathan" wrote:
                      [color=blue]
                      > I'd like to use an enumeration as a datasource for a drop-down box. Is there
                      > a way to do this?[/color]

                        Comment

                        • Jay B. Harlow [MVP - Outlook]
                          #7
                          Re: Binding to an enumeration

                          Dennis,
                          The following code "simplifies " this concept:

                          | dim mySelectedEnum as myEnum
                          |
                          | 'Display the Enum names in the combo box
                          | myComboBox.Data Source = [Enum].GetValues(GetT ype(myEnum))
                          |
                          | 'Get the selected Enum
                          | mySelectedEnum = DirectCast(myCo mboBox.Selected Item, myEnum)

                          Notice the actual bind is the same amount of code, however the get selected
                          value is significantly simplified.

                          --
                          Hope this helps
                          Jay B. Harlow [MVP - Outlook]
                          ..NET Application Architect, Enthusiast, & Evangelist
                          T.S. Bradley - http://www.tsbradley.net


                          "Dennis" <Dennis@discuss ions.microsoft. com> wrote in message
                          news:547F594D-2C20-477F-A3AB-486F84AE2003@mi crosoft.com...
                          | The following code binds an enum to a combo-box and then retrieves the
                          Enum
                          | that is selected in the combo-box:
                          |
                          | dim mySelectedEnum as myEnum
                          |
                          | 'Display the Enum names in the combo box
                          | myComboBox.Data Source = [Enum].GetNames(GetTy pe(myEnum))
                          |
                          | 'Get the selected Enum
                          | mySelectedEnum = CType([Enum].Parse(GetType( myEnum), _
                          | myComboBox.Sele ctedItem.ToStri ng), myEnum)
                          |
                          | Hope this helps.
                          | --
                          | Dennis in Houston
                          |
                          |
                          | "Nathan" wrote:
                          |
                          | > I'd like to use an enumeration as a datasource for a drop-down box. Is
                          there
                          | > a way to do this?


                            Comment

                            • Dennis
                              #8
                              Re: Binding to an enumeration

                              Thanks for shortened tip. I was really trying to write it such that it was
                              general for comboboxes that were only strings that would convert a string
                              entered into a Enum.
                              --
                              Dennis in Houston


                              "Jay B. Harlow [MVP - Outlook]" wrote:
                              [color=blue]
                              > Dennis,
                              > The following code "simplifies " this concept:
                              >
                              > | dim mySelectedEnum as myEnum
                              > |
                              > | 'Display the Enum names in the combo box
                              > | myComboBox.Data Source = [Enum].GetValues(GetT ype(myEnum))
                              > |
                              > | 'Get the selected Enum
                              > | mySelectedEnum = DirectCast(myCo mboBox.Selected Item, myEnum)
                              >
                              > Notice the actual bind is the same amount of code, however the get selected
                              > value is significantly simplified.
                              >
                              > --
                              > Hope this helps
                              > Jay B. Harlow [MVP - Outlook]
                              > ..NET Application Architect, Enthusiast, & Evangelist
                              > T.S. Bradley - http://www.tsbradley.net
                              >
                              >
                              > "Dennis" <Dennis@discuss ions.microsoft. com> wrote in message
                              > news:547F594D-2C20-477F-A3AB-486F84AE2003@mi crosoft.com...
                              > | The following code binds an enum to a combo-box and then retrieves the
                              > Enum
                              > | that is selected in the combo-box:
                              > |
                              > | dim mySelectedEnum as myEnum
                              > |
                              > | 'Display the Enum names in the combo box
                              > | myComboBox.Data Source = [Enum].GetNames(GetTy pe(myEnum))
                              > |
                              > | 'Get the selected Enum
                              > | mySelectedEnum = CType([Enum].Parse(GetType( myEnum), _
                              > | myComboBox.Sele ctedItem.ToStri ng), myEnum)
                              > |
                              > | Hope this helps.
                              > | --
                              > | Dennis in Houston
                              > |
                              > |
                              > | "Nathan" wrote:
                              > |
                              > | > I'd like to use an enumeration as a datasource for a drop-down box. Is
                              > there
                              > | > a way to do this?
                              >
                              >
                              >[/color]

                                Comment

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