CSLA .NET

You certainly can create your own Common Rules module/class.  You can even take CommonRules.StringRequired as a basis for your own rule “LastNameRule”.  I personally think that this is a good idea.  The only thing I would suggest is not to make these rules any BO specific, but create them generically just like Common Rules.  This way you will not couple unrelated objects.

Ex:

Public Function LastNameRule( _

      ByVal target As Object, ByVal e As RuleArgs) As Boolean

      Dim value As String = _

        CStr(CallByName(target, e.PropertyName, CallType.Get))

      If Len(value) = 0 Then

        e.Description = _

          String.Format(My.Resources.StringRequiredRule, RuleArgs.GetPropertyName(e))

        Return False

      Else

                If value.Lenght>20

                                e. Description = My.Resource.LastNameRuleTooLong ‘ or some other message

                                Return False

                Else

                                Return True

                End If

       End If

    End Function

Sergey Barskiy

Senior Consultant

office: 678.405.0687 | mobile: 404.388.1899

Microsoft Worldwide Partner of the Year | Custom Development Solutions, Technical Innovation

Some time ago I thought that someone posted about this topic but I have been unable to find the article I'm thinking about. Basically I would like to know if it is possible and/or advisable to share validation rules across objects.

For example, let's assume that I have several objects that have a 'LastName' property and I would like to make sure that 1) Last name is always required and 2) The length of last name can not exceed say 20 characters.

I can easily do this in one object and also copy and paste to any other objects that use LastName but I would like to create maybe one global place to store these 'common' validations.

Any ideas?

Thanks,

Not really.  I just copied code from CSLA version I am using.  Feel free to replace them with reflection calls.  I think you were thinking of target.GetType.GetProperty(e.PropertyName).GetValue(target, Nothing)…   Sounds good to me.

Sergey Barskiy

Senior Consultant

office: 678.405.0687 | mobile: 404.388.1899

Microsoft Worldwide Partner of the Year | Custom Development Solutions, Technical Innovation

Thanks Sergey. I do have another question though. I am using VB but I am always hesitant to use "old" VB methods like CallByName. Is there any particular reason you chose this method instead of using reflection?

Thanks,
John

You are correct, there is.  If you use binding flags parameter for GetType.GetProperty, one of the binding flags is case-insensitive flag.

Sergey Barskiy

Senior Consultant

office: 678.405.0687 | mobile: 404.388.1899

Microsoft Worldwide Partner of the Year | Custom Development Solutions, Technical Innovation

One nice thing about CallByName is that it is case insensitive so if you make a casing mistake in one of your strings (Lastname vs LastName) then CallByName still works. Reflection is case sensitive. Although there is probably a parameter somewhere that will make it case insentive - I just haven't looked.

Joe