How to get table record count by passing table name as parameter using LINQ TO SQL - vb.net

Question

I have a method called getTableRecordCount.
Public Function getTableRecordCount(ByVal strTableName As String, ByVal iParam1 As Integer, iParam2 As Integer) As Boolean
Try
Dim detailReturned = (From paramTableName In dc.<need to pass the strTableName here>
Where paramTableName.col1 = iParam1 And paramTableName.col2 = iParam2
Select paramTableName).Count
If (detailReturned > 0) Then
Return True
Else
Return False
End If
Catch ex As Exception
.....
End Try
End Function
If I can pass the table name and have the DataContext I can use the same method for getting other tables
record count. Any input on how to achieve this?

Answer 1

You could create a method where you pass a data context and expression.
Then from data context (based on Linq2Sql as you did not specify framework) you can get table by using
GetTable<T>()
method on your data context.
Expression would be your parameters.
Hope it helps.

Answer 2

Hopefully my VB is okay; I'm more comfortable in C#. I'm not sure if this would work with LINQ to SQL, but the GetTableRecordCount test near the bottom does pass. I'm assuming you're working with different data types in your tables, hence the generic method.
Imports System.Text
Imports System.Linq.Expressions
Class Product
Public Id As Integer
Public Name As String
Sub New(id As Integer, name As String)
Me.Id = id
Me.Name = name
End Sub
End Class
Class Order
Public Id As Integer
Public NumberOfItems As Integer
Sub New(id As Integer, numItems As String)
Me.Id = id
Me.NumberOfItems = numItems
End Sub
End Class
Class DataContext
Public Property Products As IEnumerable(Of Product)
Public Property Orders As IEnumerable(Of Order)
Sub New()
Me.Products = New Product() {New Product(1, "Apple"), New Product(2, "Banana")}
Me.Orders = New Order() {New Order(1, 20), New Order(2, 50)}
End Sub
End Class
<TestClass()>
Public Class Main
Dim MyDataContext As DataContext
<TestMethod()>
Public Sub GetTableRecordCount()
Me.MyDataContext = New DataContext()
Assert.IsTrue(Me.GetTableRecordCount(Of Product)("Products", Function(p) p.Id, 1, Function(p) p.Name.Length, 5))
Assert.IsTrue(Me.GetTableRecordCount(Of Order)("Orders", Function(o) o.Id, 2, Function(o) o.NumberOfItems, 50))
End Sub
Private Function GetTableRecordCount(Of TRow)(tableName As String, getParam1 As Func(Of TRow, Integer), iParam1 As Integer, getParam2 As Func(Of TRow, Integer), iParam2 As Integer) As Boolean
Try
Dim propertyExpr = Expression.Property(Expression.Constant(Me.MyDataContext), tableName)
Dim getTableData = Expression.Lambda(Of Func(Of IEnumerable(Of TRow)))(propertyExpr).Compile()
Dim detailReturned =
From row In getTableData()
Where getParam1(row) = iParam1 And getParam2(row) = iParam2
Select row
Return detailReturned.Count() > 0
Catch ex As Exception
Return False
End Try
End Function
End Class