Passing nested data from Controller to View in ASP.Net MVC (LINQ)

Question

I'm using LINQ to SQL (SQL Server) within ASP.Net MVC. My page needs to display all Regions and all Offices within each Region (nested). Offices belong to a Suburb, which in turn, belong to a Region. I.e. Within each Region, I need to grab the Offices which exist inside Suburbs which belong to the current Region in the loop.

(Pseudo code)

    foreach(Region currentRegion in Regions)  
    {  
        Display Region's Heading  
        foreach(Office currentOffice in ALL OFFICES WHICH BELONG TO SUBURBS WHICH BELONG TO THIS REGION)  
        {  
             Display Office Name  
        }  
    }  

What is the cleanest, MVC paradigm way to achieve this with LINQ to SQL?
(I'm a massive SQL fan, but I'm using LINQ to SQL for this project).

I don't want to have to write 5 helper classes just to do such a simple thing. I am not looking for a "perfect world OO overkill" solution, clean, minimalist and simple is best.

I'd ideally like to assemble all the data in the Controller so that I don't end up with some chaotic view that overlaps with Controller responsibility etc.

Many thanks..

Answer 1

In your case,

• i would create view model classes RegionModel, SuburbModel, OfficeModel.
• Using AutoMapper, i would map Region to RegionModel and pass it to view

• View would look like this (Spark) =>

  <viewdata model="RegionModel region" />
  <for each="var suburb in region.Suburbs">
      <span each="var office in suburb.Offices">${office.Name}</span>
  </for>        
  

That's an answer to question 'how to pass nested data to view in asp.net-mvc?'. Thing is - your Model does not fit to this yet (Region class is not directly bound with Suburbs, Suburbs with Offices).

So - you need to make sure your Region contains Suburbs and Suburb contains Offices. I'm not sure about L2S but in nhibernate that would be easy - collections would be mapped as is and by default - kept lazy loaded. RegionController would be responsible for using RegionRepository properly and RegionRepository should provide possibility to eager load suburbs & offices on demand.