Dynamic conversion based on business object field data type

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Dynamic conversion based on business object field data type

Author	Message
Tim Dol	Tim Dol posted 15 Years Ago Topic Details Share Topic
Group: Forum Members Posts: 340, Visits: 1.4K	I am trying to write a generic import routine that imports data into a business object and need some help on data conversion issue. Example: Say I have a datatable containing the data I want to import. Assume the column names in the import file match the business object's column names. I have my customer object and want to populate it. Dim loBO as New CustomerBO For Each Row As DataRow In ImportFileDataTable.Rows loBO.NewRow() loBO.CurrentRow.Item("CompanyName") = Row.Item("CompanyName") etc... Next This works fine but now I want to ensure the data from the import file converts to the appropriate type based on the business object. Example: The BO field may be integer but the data coming from the import datatable may be string... I want to convert this to the proper type. I tried this... Dim loType as Type Dim loBO as New CustomerBO For Each Row As DataRow In ImportFileDataTable.Rows loBO.NewRow() loType = GetType(loBO.CurrentRow.Item("CompanyName").GetType loBO.CurrentRow.Item("CompanyName") = Ctype(Row.Item("CompanyName"),loType) etc... Next Problem is 'loType' is not a valid variable for this statement... Is there anyway to dynamically set this type according to the data type on the business object without have to add a bunch of conditional statements? Thanks, Tim
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Peter Jones	Peter Jones posted 15 Years Ago Post Details Share Post
Group: Forum Members Posts: 386, Visits: 2.1K	Hi Tim, This is out of my league but couldn't you use: loBO.CurrentRow.Item("CompanyName") = Ctype(Row.Item("CompanyName"), GetType(loBO.CurrentRow.Item("CompanyName").GetType) But this code will, of course, fail if the data can't be conversted , e.g. "ABC" into an integer. Cheers, Peter
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Tim Dol	Tim Dol posted 15 Years Ago Post Details Share Post
Group: Forum Members Posts: 340, Visits: 1.4K	I tried that Peter. Visual Studio displays a syntax error 'Type loBO.CurrentRow.Item is not defined'
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Ivan George Borges	Ivan George Borges posted 15 Years Ago Post Details Share Post
Group: StrataFrame MVPs Posts: 1.9K, Visits: 21K	Hi Tim! I will throw some ideas of what I have done here to get "types". Maybe it can help you. To get a System.Type of a SqlDBType: ''' <summary> ''' Find out the SqlDbType of a System.Type variable ''' </summary> ''' <param name="theType"></param> ''' <returns></returns> ''' <remarks></remarks> Public Shared Function GetDBType(ByVal theType As System.Type) As SqlDbType Dim p1 As SqlClient.SqlParameter Dim tc As System.ComponentModel.TypeConverter p1 = New SqlClient.SqlParameter() tc = System.ComponentModel.TypeDescriptor.GetConverter(p1.DbType) If tc.CanConvertFrom(theType) Then p1.DbType = CType(tc.ConvertFrom(theType.Name), DbType) Else 'Try brute force Try p1.DbType = CType(tc.ConvertFrom(theType.Name), DbType) Catch ex As Exception 'Do Nothing End Try End If Return p1.SqlDbType End Function To find out a Column type, in order to set defaults: '-- set default value Dim lb As Byte lb = CType(0, Byte) Select Case columnType.ToString Case "System.String" col.DefaultValue = "" Case "System.Int32" col.DefaultValue = CType(0, Integer) Case "System.Boolean" col.DefaultValue = False Case "System.Decimal" col.DefaultValue = CType(0, Decimal) Case "System.Byte" col.DefaultValue = CType(0, Byte) Case "System.DateTime" col.DefaultValue = "1800-01-01 00:00:00.000" End Select To convert a System.Data.DbType into a System.Type: Public Shared Function GetSystemType(ByVal DbType As System.Data.DbType) As System.Type '-- establish locals Dim stType As System.Type = GetType(System.String) '-- test the sent DbType Select Case DbType Case Data.DbType.String, Data.DbType.AnsiString, Data.DbType.AnsiStringFixedLength, _ Data.DbType.StringFixedLength stType = GetType(System.String) Case Data.DbType.Int32 stType = GetType(System.Int32) Case Data.DbType.Boolean stType = GetType(System.Boolean) Case Data.DbType.Decimal, Data.DbType.Currency stType = GetType(System.Decimal) Case Data.DbType.Byte, Data.DbType.SByte stType = GetType(System.Byte) Case Data.DbType.Date, Data.DbType.DateTime, Data.DbType.DateTime2 stType = GetType(System.DateTime) End Select '-- return converted System.Type Return stType End Function
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