WA3.1 Escape procedures

The role of the Escape procedures is to allow adaptation of the Web Applications to different insurance contexts. There are situated in a single class EscapeBL, which makes it easier to access and modify without having to worry about messing with the whole Web Application source code. 

There are 2 escape procedures that can be modified: 

1. isValidInsuranceNumber allows validating the insuree number based on predefined rules. It is used for example when a new family or insuree are enrolled in openIMIS to ensure the valid insuree number and to prevent typing errors.
2. SendSMS allows sending SMS messages through a specific SMS Gateway. 

In this guide, we will localise the isValidInsuranceNumber method. 

This is the generic implementation of the method:

Public Function isValidInsuranceNumber(ByVal InsuranceNumber As String) As Boolean
   Return True
End Function

The generic method is returning always true, meaning any insuree number will be a valid one. 

Let's take for example the following insuree number requirements:

1. The insuree number must follow the modulo 9 rule: the last digit is the modulo 9 of the number without the last digit
2. The insuree number must have 10 digits ('0' at the beginning must be saved)

These requirements are satisfied by the following escape procedure: 

Public Function isValidInsuranceNumber(ByVal InsuranceNumber As String) As Boolean
    If Not InsuranceNumber.ToString.Length = 10 Then Return False
    Dim N As String = Left(InsuranceNumber.ToString, 9)
    Dim Modulo As String = Right(InsuranceNumber.ToString, 1)
    If Modulo = N - (Int(N / 7) * 7) Then Return True
    Return False
End Function

The isValidInsuranceNumber is executing the following steps: 

1. validates the length of the insuree number
2. splits the insuree number into number and modulo parts 
3. validates that the modulo value is equal to the modulo result

Other validations rules can be applied.