Right now I’m working on a very big banking solution developed in VB6. The application is massively form-based and lacks a layered architecture (all the code for data access, business logic and form manipulation is in the single form class). My job is now to refactor this code. I'm writing a proper business logic layer and data access layer in C# and the form will remain in VB.
Here are code snippets:
public class DistrictDAO
{
public string Id{get;set;}
public string DistrictName { get; set; }
public string CountryId { get; set; }
public DateTime SetDate { get; set; }
public string UserName { get; set; }
public char StatusFlag { get; set; }
}
District Entity class, why its extension is DAO, Im not clear.
public class DistrictGateway
{
#region private variable
private DatabaseManager _databaseManager;
#endregion
#region Constructor
public DistrictGateway(DatabaseManager databaseManager) {
_databaseManager = databaseManager;
}
#endregion
#region private methods
private void SetDistrictToList(List<DistrictDAO> dataTable, int index, DistrictDAO district){
// here is some code for inserting
}
#endregion
#region public methods
try
{
/*
query and rest of the codes
*/
}
catch (SqlException sqlException)
{
Console.WriteLine(sqlException.Message);
throw;
}
catch (FormatException formateException)
{
Console.WriteLine(formateException.Message);
throw;
}
finally {
_databaseManager.ConnectToDatabase();
}
public void InsertDistrict() {
// all query to insert object
}
public void UpdateDistrict() {
}
#endregion
}
DistrictGateway class responsible for database query handling Now the business layer.
public class District
{
public string Id { get; set; }
public string DistrictName { get; set; }
public string CountryId { get; set; }
}
public class DistrictManager
{
#region private variable
private DatabaseManager _databaseManager;
private DistrictGateway _districtGateway;
#endregion
#region Constructor
public DistrictManager() {
// Instantiate the private variable using utitlity classes
}
#endregion
#region private method
private District TransformDistrictBLLToDL(DistrictDAO districtDAO) {
// return converted district with lots of coding here
}
private DistrictDAO TransformDistrictDLToBLL(District district)
{
// return converted DistrictDAO with lots of coding here
}
private List<District> TransformDistrictBLLToDL(List<DistrictDAO> districtDAOList)
{
// return converted district with lots of coding here
}
private List<DistrictDAO> TransformDistrictDLToBLL(List<District> district)
{
// return converted DistrictDAO with lots of coding here
}
#endregion
#region public methods
public List<District> GetDistrict() {
try
{
_databaseManager.ConnectToDatabase();
return TransformDistrictBLLToDL( _districtGateway.GetDistrict());
}
catch (SqlException sqlException)
{
Console.WriteLine(sqlException.Message);
throw;
}
catch (FormatException formateException)
{
Console.WriteLine(formateException.Message);
throw;
}
finally {
_databaseManager.ConnectToDatabase();
}
}
#endregion
This is the code for the business layer.
My questions are:
- Is it a perfect design?
- If not, what are flaws here?
- I think, this code with duplicated try catch block
- What can be good design for this implementation
