Where do objects merge/join data in a 3-tier model?
- by BerggreenDK
Its probarbly a simple 3-tier problem. I just want to make sure we use the best practice for this and I am not that familiary with the structures yet.
We have the 3 tiers:
GUI: ASP.NET for Presentation-layer (first platform)
BAL: Business-layer will be handling the logic on a webserver in C#, so we both can use it for webforms/MVC + webservices
DAL: LINQ to SQL in the Data-layer, returning BusinessObjects not LINQ.
DB: The SQL will be Microsoft SQL-server/Express (havent decided yet).
Lets think of setup where we have a database of [Persons]. They can all have multiple [Address]es and we have a complete list of all [PostalCode] and corresponding citynames etc.
The deal is that we have joined a lot of details from other tables.
{Relations}/[tables]
[Person]:1 --- N:{PersonAddress}:M --- 1:[Address]
[Address]:N --- 1:[PostalCode]
Now we want to build the DAL for Person. How should the PersonBO look and when does the joins occure?
Is it a business-layer problem to fetch all citynames and possible addressses pr. Person? or should the DAL complete all this before returning the PersonBO to the BAL ?
Class PersonBO
{
public int ID {get;set;}
public string Name {get;set;}
public List<AddressBO> {get;set;} // Question #1
}
// Q1: do we retrieve the objects before returning the PersonBO and should it be an Array instead? or is this totally wrong for n-tier/3-tier??
Class AddressBO
{
public int ID {get;set;}
public string StreetName {get;set;}
public int PostalCode {get;set;} // Question #2
}
// Q2: do we make the lookup or just leave the PostalCode for later lookup?
Can anyone explain in what order to pull which objects? Constructive criticism is very welcome. :o)
