学步园

Imports System.Collections.Generic
Imports System.Data.OleDb
Imports System.Reflection

Public Class ParametersBuilder(Of T)
    Private allNames As String()
    Private setNames As List(Of String)

    Sub New()
        Dim props() As PropertyInfo = GetType(T).GetProperties
        allNames = (From p In props Select p.Name).ToArray
        setNames = allNames.ToList
    End Sub

    Public Sub SetFields(ByVal ParamArray fields() As String)
        Dim list As New List(Of String)
        For Each field In fields
            If allNames.Contains(field) Then
                list.Add(field)
            End If
        Next
        If list.Count > 0 Then
            setNames = list
        End If
    End Sub

    Public Function GetParameters(ByVal obj As T) As OleDbParameter()
        Dim list As New List(Of OleDbParameter)
        For Each name In setNames
            Dim prop As PropertyInfo = GetType(T).GetProperty(name)
            Dim p As New OleDbParameter
            p.ParameterName = name
            p.Value = prop.GetValue(obj, Nothing)
            If p.Value IsNot Nothing Then
                list.Add(p)
            End If
        Next
        Return list.ToArray
    End Function

    Public Function GetFields(ByVal parms As OleDbParameter()) As String
        Dim arr = From p In parms Select p.ParameterName
        Return String.Join(",", arr)
    End Function

    Public Function GetVFields(ByVal parms As OleDbParameter()) As String
        Dim arr = From p In parms Select "@" & p.ParameterName
        Return String.Join(",", arr)
    End Function
End Class