• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 468
  • Last Modified:

Run vb function whose name is stored in a database

I have a data table with Function names.
These functions are defined in my code and work properly.
Most of these functions return a value I require.
I can retrieve the function name from the database but I don't know to invoke the function in vb.net

Should I be retrieving the function name from the database into a string field ?
How would I run/execute the function with parameters
Can you provide a small example
0
swendell
Asked:
swendell
1 Solution
 
Kevin CrossChief Technology OfficerCommented:
If your table contains data like this:

FunctionName, Param1, Param2, Param3

What you could do is retrieve the values from database as strings or if parameters are numbers as integers.  Then use a case logic or if statement to determine which function to call.

If dr("FunctionName") = "MyFunction1" Then
    MyFunction1(dr("Param1"), dr("Param2"), dr("Param3"))
End If

Where dr is your SqlDataReader for example, but however you retrieve data is inconsequential to my point so hopefully it is clear.
0
 
swendellAuthor Commented:
I can retrieve function name into a string but then I want to run that function.
BUT keep in mind I have many functions and I am not hard-coding every possible function name/value as you did in the example above. In concept looking for something more like this:

Dim myFunction = FunctionNameFromDatabase as string
Execute myFunction & "(" & parameter1 & ")"

0
 
madivad2Commented:
You are after the "CallByName" Function... refer these links:

http://msdn.microsoft.com/en-us/library/22x2chfx.aspx    and
http://msdn.microsoft.com/en-us/library/chsc1tx6.aspx
0
Get expert help—faster!

Need expert help—fast? Use the Help Bell for personalized assistance getting answers to your important questions.

 
madivad2Commented:
Note: Your function or sub MUST be public!

Some sample code for good measure:
Private Sub button_click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        CallByName(Me, "MyBeep", CallType.Method)
End Sub
 
Public Sub MyBeep()
    Beep()
End Sub

Open in new window

0
 
Mike TomlinsonMiddle School Assistant TeacherCommented:
CallByName() will work fine...but if you want the ".Net approved" method then you'll want to use Reflection.  The method/function doesn't have to Public with this approach:

Imports System.Reflection
Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim strIn As String = "Idle_Mind"
        Dim retValue As Integer = 0
        Dim functionName As String = "Foo"

        Dim mi As MethodInfo = Me.GetType.GetMethod(functionName, BindingFlags.Instance Or BindingFlags.Public Or BindingFlags.NonPublic)
        retValue = mi.Invoke(Me, New Object() {strIn})
        MessageBox.Show("retValue = " & retValue, "Return value of Foo()", MessageBoxButtons.OK, MessageBoxIcon.Information)
    End Sub

    Private Function Foo(ByVal param As String) As Integer
        MessageBox.Show("param = " & param, "Inside Foo()", MessageBoxButtons.OK, MessageBoxIcon.Information)
        Return IIf(param.ToLower = "idle_mind", 1, 0)
    End Function

End Class


Some more examples:
http://www.experts-exchange.com/Programming/Languages/.NET/Visual_Basic.NET/Q_22055463.html#17911012
0
 
swendellAuthor Commented:
madivad2: That was it. I only needed to add a comma and insert the parameter like this:
CallByName(Me, "MyBeep", CallType.Method, parameter)
I forgot the Me since the function is in the same area
0
 
swendellAuthor Commented:
Thank you
0
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

Featured Post

The 14th Annual Expert Award Winners

The results are in! Meet the top members of our 2017 Expert Awards. Congratulations to all who qualified!

Tackle projects and never again get stuck behind a technical roadblock.
Join Now