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enumerating an objects properites 2

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ghost807

ghost807

IS-IT--Management
Jun 27, 2003
99
US
i have several classes that i have created
customer
job
material
truck

each class has a bunch of different properties
what i would like to do is create a generic database connection that i could use to update, retreive, delete, or add to the database.

now the question is how do i do this the best way (with oop in mind)


if i'm retreiving i send the name to the database class and it will pass back one of the objects.

if i'm adding or updating i pass the object to the database class and let it do it's work.


Finally i get the point of the message!!!!!
How do i pass an object to the database class and have it:
recognize what the object is
read each property and also it's value.

i don't know if what i'm asking is worth doing or not but right now i have to create a class(truck,customer,job,etc) and then create a class to handle the db stuff(dbcustomer,dbjob,dbtruck,etc)
i would like to remove the multiple dbclasses.
i think this should work because the tables i have created in the database have the same names and structures as the objects.


thanx for your imput.
(here is some code to help with the descriptions)

just a few button clicks to show how i'm implementing
Code: 
    Private Sub btnJobFind_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnJobFind.Click
        StatusBar.Text = "Retreiving Job Names"
        Dim Job As New clsJob
        Dim JobDB As New DBJob
        Job = JobDB.GetJob(txtJobFind.Text)
        With Job
            Me.txtJobNumber.Text = .JobNumber
            Me.txtJobDescription1.Text = .Description(1)
            Me.txtJobDescription2.Text = .Description(2)
            Me.txtJobDescription3.Text = .Description(3)
            Me.txtJobDescription4.Text = .Description(4)
            Me.txtJobComment1.Text = .Comment(1)
            Me.txtJobComment2.Text = .Comment(2)
            Me.txtJobComment3.Text = .Comment(3)
            Me.txtJobComment4.Text = .Comment(4)
        End With
        StatusBar.Text = ""
        txtCustomer.Text = ""
        Me.txtJobFind.Text = ""
    End Sub

Code: 
    Private Sub btnJobUpdate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnJobUpdate.Click
        Dim Job As New clsJob
        Dim JobDB As New DBJob
        With Job
            .JobNumber = Me.txtJobNumber.Text
            .Description(1) = Me.txtJobDescription1.Text
            .Description(2) = Me.txtJobDescription2.Text
            .Description(3) = Me.txtJobDescription3.Text
            .Description(4) = Me.txtJobDescription4.Text
            .Comment(1) = Me.txtJobComment1.Text
            .Comment(2) = Me.txtJobComment2.Text
            .Comment(3) = Me.txtJobComment3.Text
            .Comment(4) = Me.txtJobComment4.Text
        End With
        JobDB.UpdateJob(Job)
        Me.txtJobNumber.Text = ""
        Me.txtJobDescription1.Text = ""
        Me.txtJobDescription2.Text = ""
        Me.txtJobDescription3.Text = ""
        Me.txtJobDescription4.Text = ""
        Me.txtJobComment1.Text = ""
        Me.txtJobComment2.Text = ""
        Me.txtJobComment3.Text = ""
        Me.txtJobComment4.Text = ""

    End Sub

this is my job object

Code: 
#Region "Constants"
    Private myJobNumber As String
    Const MAXDESCRIPTION As Integer = 4
    Const MAXCOMMENT As Integer = 4
    Const MAX_UDF As Integer = 10

    Private myDescription(MAXDESCRIPTION) As String
    Private myComment(MAXCOMMENT) As String
    Private myUDF(MAX_UDF) As String
#End Region

#Region "Properties"
    Public Property JobNumber() As String
        Get
            Return myJobNumber
        End Get
        Set(ByVal Value As String)
            myJobNumber = Value
        End Set
    End Property

    Public Property Description(ByVal index As Integer) As String
        Get
            Return myDescription(index)
        End Get
        Set(ByVal Value As String)
            myDescription(index) = Value
        End Set
    End Property

    Public Property Comment(ByVal index As Integer) As String
        Get
            Return myComment(index)
        End Get
        Set(ByVal Value As String)
            myComment(index) = Value
        End Set
    End Property

    Public Property UDF(ByVal index As Integer) As String
        Get
            Return myUDF(index)
        End Get
        Set(ByVal Value As String)
            myUDF(index) = Value
        End Set
    End Property

#End Region
the dbconnection workhorse
Code: 
Public Class DBJob
    Public Function GetJob(ByVal JobNumber As String) As clsJob
        Try
            Dim IDX As Integer = 0
            Dim job As New clsJob
            Dim Ds As New TestAppDB
            Dim Connect As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & _
            Application.ExecutablePath.Substring(0, Application.ExecutablePath.Length - 11) & "testappdb.mdb"
            Dim adapter As New OleDbDataAdapter("SELECT * FROM tblJob WHERE JobNumber LIKE " & _
            Chr(34) & "%" & JobNumber & "%" & Chr(34), Connect)
            adapter.Fill(Ds, "tblJob")


            For IDX = 0 To Ds.tblJob.Rows.Count - 1
                Dim idx1 As Integer
                For idx1 = 0 To Ds.tblJob.Columns.Count - 1
                    If Ds.tblJob(IDX).Item(idx1) Is DBNull.Value Then
                        Ds.tblJob(IDX).Item(idx1) = ""
                    End If
                Next

                With job
                    .JobNumber = Ds.tblJob(IDX).JobNumber
                    .Description(1) = Ds.tblJob(IDX).Description1
                    .Description(2) = Ds.tblJob(IDX).Description2
                    .Description(3) = Ds.tblJob(IDX).Description3
                    .Description(4) = Ds.tblJob(IDX).Description4
                    .Comment(1) = Ds.tblJob(IDX).Comment1
                    .Comment(2) = Ds.tblJob(IDX).Comment2
                    .Comment(3) = Ds.tblJob(IDX).Comment3
                    .Comment(4) = Ds.tblJob(IDX).Comment4
                    .UDF(1) = Ds.tblJob(IDX).UDF1
                    .UDF(2) = Ds.tblJob(IDX).UDF2
                    .UDF(3) = Ds.tblJob(IDX).UDF3
                    .UDF(4) = Ds.tblJob(IDX).UDF4
                    .UDF(5) = Ds.tblJob(IDX).UDF5
                    .UDF(6) = Ds.tblJob(IDX).UDF6
                    .UDF(7) = Ds.tblJob(IDX).UDF7
                    .UDF(8) = Ds.tblJob(IDX).UDF8
                    .UDF(9) = Ds.tblJob(IDX).UDF9
                    .UDF(10) = Ds.tblJob(IDX).UDF10
                End With
            Next
            Ds.Dispose()
            adapter.Dispose()
            Return job
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try

    End Function

    Public Sub UpdateJob(ByVal Job As clsJob)
        Try
            Dim Connect As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & _
            Application.ExecutablePath.Substring(0, Application.ExecutablePath.Length - 11) & "testappdb.mdb"

            Dim conn As New OleDbConnection(Connect)
            Dim adapter As New OleDbDataAdapter
            Dim SQLString As String = "SELECT * FROM tblJob WHERE JobNumber = " & Chr(34) & Job.JobNumber & Chr(34)
            adapter.SelectCommand = New OleDbCommand(SQLString, conn)
            Dim cmdbuilder As New OleDbCommandBuilder(adapter)
            conn.Open()
            Dim JobUpdate As New TestAppDB
            adapter.TableMappings.Add("Table", "tblJob")
            adapter.Fill(JobUpdate.Tables("tblJob"))
            Dim idx As Integer
            For idx = 0 To JobUpdate.tblJob.Rows.Count - 1
                With Job
                    If Job.JobNumber.ToUpper = JobUpdate.tblJob(idx).JobNumber.ToUpper Then
                        JobUpdate.tblJob(idx).Description1 = .Description(1)
                        JobUpdate.tblJob(idx).Description2 = .Description(2)
                        JobUpdate.tblJob(idx).Description3 = .Description(3)
                        JobUpdate.tblJob(idx).Description3 = .Description(4)
                        JobUpdate.tblJob(idx).Comment1 = .Comment(1)
                        JobUpdate.tblJob(idx).Comment2 = .Comment(2)
                        JobUpdate.tblJob(idx).Comment3 = .Comment(3)
                        JobUpdate.tblJob(idx).Comment4 = .Comment(4)
                        JobUpdate.tblJob(idx).UDF1 = .UDF(1)
                        JobUpdate.tblJob(idx).UDF2 = .UDF(2)
                        JobUpdate.tblJob(idx).UDF3 = .UDF(3)
                        JobUpdate.tblJob(idx).UDF4 = .UDF(4)
                        JobUpdate.tblJob(idx).UDF5 = .UDF(5)
                        JobUpdate.tblJob(idx).UDF6 = .UDF(6)
                        JobUpdate.tblJob(idx).UDF7 = .UDF(7)
                        JobUpdate.tblJob(idx).UDF8 = .UDF(8)
                        JobUpdate.tblJob(idx).UDF9 = .UDF(9)
                        JobUpdate.tblJob(idx).UDF10 = .UDF(10)

                        Dim idx1 As Integer
                        For idx1 = 0 To JobUpdate.tblJob.Columns.Count - 1
                            If JobUpdate.tblJob(idx).Item(idx1) Is "" Then
                                JobUpdate.tblJob(idx).Item(idx1) = DBNull.Value
                            End If
                        Next
                    End If
                End With
            Next
            adapter.Update(JobUpdate)
            adapter.Dispose()
            JobUpdate.Dispose()
            conn.Dispose()

        Catch ex As Exception
            MsgBox(ex.Message)
        End Try

    End Sub
 
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YOu can use Reflection (System.Reflection namespace) and call a GetType() on your type to get a Type object. Once you have that, you can call GetProperties() to get a list of properties that it exposes. You can then iterate through that list, mapping property names to database column names.

Chip H.


____________________________________________________________________
If you want to get the best response to a question, please read FAQ222-2244 first
 
Upvote 0 Downvote
I think chmohan s a man of little words and one URL.

Christiaan Baes
Belgium

I just like this --> [Wiggle] [Wiggle]
 
Upvote 0 Downvote
ok so far so good. the link you provided was fantastic.
but.......
i need to make it so that i can substitute in the table name that is taken from my class
Code: 
            Dim myType As Type = AddItem.GetType
            Dim tblName As String = "tbl" & myType.Name.Substring(3)
            Dim cRow As TestAppDB.tblMaterialRow = addable.tblMaterial.NewtblMaterialRow

and i would need it to look something like this

Code: 
            Dim myType As Type = AddItem.GetType
            Dim tblName As String = "tbl" & myType.Name.Substring(3)
            Dim cRow As TestAppDB.tblName & "Row" = addable.tblname.New & tblName & Row    'I know this isn't right but it helps explain what i'm trying to do.

but i cannot seem to figure out how to do that.
any suggestions.
 
Upvote 0 Downvote
ok all seems to be going well.
this is the last problem that i seem to be having.
thanx for your help so far.

any suggestions?


Code: 
    Public Sub AddInfo(ByVal AddItem As Object)
        Dim myType As Type = AddItem.GetType
        Try
            Dim Connect As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & Application.ExecutablePath.Substring(0, Application.ExecutablePath.Length - 11) & "testappdb.mdb"
            Dim Conn As New OleDbConnection(Connect)
            Dim adapter As New OleDbDataAdapter

            Dim tblName As String = "tbl" & myType.Name.Substring(3)
            adapter.SelectCommand = New OleDbCommand("SELECT * FROM " & tblName, Conn)
            Dim cmdbuilder As OleDbCommandBuilder = New OleDbCommandBuilder(adapter)
            Conn.Open()

            Dim addable As New TestAppDB
            adapter.TableMappings.Add("Table", tblName)
            adapter.Fill(addable.Tables(tblName))

            Dim cRow As DataRow = addable.Tables(tblName).NewRow

            Dim myPropertyInfo As PropertyInfo() = myType.GetProperties((BindingFlags.Public Or BindingFlags.Instance))
            With AddItem
                Dim i As Integer
                For i = 0 To myPropertyInfo.Length - 1
                    Dim myPropInfo As PropertyInfo = CType(myPropertyInfo(i), PropertyInfo)
                    If myPropInfo.Name.ToString = "Comment" Then
                        cRow("comment1") = .Comment(1)
                        cRow("comment2") = .Comment(2)
                        cRow("comment3") = .Comment(3)
                        cRow("comment4") = .Comment(4)
                    ElseIf myPropInfo.Name.ToString = "Description" Then
                        cRow("Description1") = .Description(1)
                        cRow("Description2") = .Description(2)
                        cRow("Description2") = .Description(3)
                        cRow("Description4") = .Description(4)
                    ElseIf myPropInfo.Name.ToString = "UDF" Then
                        cRow("UDF1") = .UDF(1)
                        cRow("UDF2") = .UDF(2)
                        cRow("UDF3") = .UDF(3)
                        cRow("UDF4") = .UDF(4)
                        cRow("UDF5") = .UDF(5)
                        cRow("UDF6") = .UDF(6)
                        cRow("UDF7") = .UDF(7)
                        cRow("UDF8") = .UDF(8)
                        cRow("UDF9") = .UDF(9)
                        cRow("UDF10") = .UDF(10)
                    ElseIf myPropInfo.Name.ToString <> "UDF" And myPropInfo.Name.ToString <> "Description" And myPropInfo.Name.ToString <> "Comment" Then
                        [COLOR=red] cRow(myPropInfo.Name.ToString) = myPropInfo.GetValue([u]myType, (i)[/u][COLOR=green]*[/color])[/color]
[COLOR=green]*[/color][COLOR=blue]'this is the last problem that i am having. i keep receiving a couple of errors.
'cannot index 1 dimension array or
'getvalue does not accept this number of arguments[/color]
                    End If
                  
                Next i
            End With
            '        ''''''''''''''''''''''''''''''''''''''''''
            '        '''Check and set Nulls else the DB will Flip Out
            '        ''''''''''''''''''''''''''''''''''''''''''
            Dim idx As Integer
            For idx = 0 To addable.Tables(tblName).Columns.Count - 1
                If cRow.Item(idx) Is "" Then
                    cRow.Item(idx) = DBNull.Value
                End If

            Next
            ''''''''''''''''''''''''''''''''''''''''''
            '''We are done. Add the row
            ''''''''''''''''''''''''''''''''''''''''''
            addable.Tables(tblName).Rows.Add(cRow)
            adapter.Update(addable)
            Conn.Close()
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End Sub
 
Upvote 0 Downvote
no, i've been here several times to see what i'm missing. but i don't see it.
according to what i see there what i have now should work correctly.

i can change myType to myPropInfo or myPropertyInfo and i still get the same errors.

if i don't use an index i will get does not accept arguments.
it's gotta be something almost basic that i'm missing,
but not being smart enough it will continue to elude me until i'm bald.
 
Upvote 0 Downvote
C:\Documents and Settings\DaveEJr\My Documents\Visual Studio Projects\testapp\DBGeneric.vb(90): Value of type 'Integer' cannot be converted to '1-dimensional array of System.Object'.


i guess that's what i thought i was doing with (i) already at the begining of my for loop.
i guess i don't quite understand(not your fault, i'm just slow after lunch)
 
Upvote 0 Downvote
chmohan
i sat up last night thinking about what you told me to do.....
but still i don't understand.
everytime i try to do what you want i get integer cannot but 1 dimensional array.
 
Upvote 0 Downvote
look if this could work

myPropInfo.GetValue(myType, nothing)


Christiaan Baes
Belgium

I just like this --> [Wiggle] [Wiggle]
 
Upvote 0 Downvote
object does not match target type
but......................
if i change mytype to AddInfo then (sweet) it works

You guys are my hero's

everytime i have problems you are there to help out and point me in the right direction.




 
Upvote 0 Downvote
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