Home/ Questions/Q 9269899
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-06-18T15:14:15+00:00

I am building two C# three-tier applications that get their data a very old

  • 0

I am building two C# three-tier applications that get their data a very old database Customer table that has about 100 columns. They perform some logic in the business layer and a presentation layer displays the data.

The layout of the customer table is – 

CustomerID
Firstname
Lastname
DateOfBirth
Othervalue1
Othervalue2
Othervalue3
.
.
Othervalue95
Creationdate
Updatedate

For these two applications I only need the customer table, but I am building the a new data access layer with Entity Framework. Future projects will need access to other tables and will add to this access layer.

I will use the Unit of work and repository patters.

My problem is the following –

Application A needs one subset of the customer table columns

and

Application B needs a different subset of the customer table columns (there is some overlap with Application A’s needs)

How do I perform mapping from the data layer to these two independent business layers? I know I can use automapper to perform mapping from an data entity class to a business layer class, but I will have two different business layer Customer classes.

I have been reading a bit about DTO’s but I don’t see where there should go in this n-tiered application.

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    You can use any of these based on your application design
    1 – Map customer table to two or more Entities
    2 – Have a base entity like CustomerBase and 2 or more sub entities.
    3 – DTOs are Data Transfer Objects and they are (normally) mutable. Changing them wont result a CRUD operation on the DB.
    DTOs are used in scenarios like: Customer entity is a heavyweight object(say 100 columns) and you just need a subset of that data (say 20 columns).
    Conversion between the DTO object and the actual Entity could be implemented in many ways like auto-mapper, manually operator oveloading and more …

    Hope this helps

    • 0