Question

I was wondering if this is possible in Linq:
I have three tables:

Request
--id
--Adress
--Description
Nav.Properties:
-- RequestStatus

RequestStatus
--RequestId
--PubDate
--StatusTypeId
Nav.Properties:
-- Request
-- StatusType

StatusType
--Id
--StatusTypeDescription
Nav.Properties
-- RequestStatus

In Linq, I can manage to get the first two table joined together with this:

var RequestWithStatus = dbContext.Requests.Include("RequestStatus").ToList<fullRequest>();

But…what I would like to have is the StatusTypeDescription column also included in this query (so use a join on a third table).

Answer 1

if a Request instance can have one RequestStatus, and a RequestStatus instance can have one StatusType, then you could simply do

var requestList = dbContext.Requests.Include("RequestStatus.StatusType").ToList();

there’s also a “lambda” (Expression>) overload for Include (in System.Data.Entity) (not sure it will work with mysql)

var requestList = dbContext.Requests.Include(m => m.RequestStatus.StatusType).ToList();

all your data will be present in the list (eager loading).

Then you can access Description

var firstRequest = requestList.First();
var requestDescription = firstRequest.Description;
var statusTypeDescription = firstRequest.RequestStatus.StatusType.Description;

or safer

var statusTypeDescription = firstRequest.RequestStatus != null && firstRequest.RequestStatus.StatusType != null 
          ? firstRequest.RequestStatus.StatusType.Description
          : string.Empty;