Question

Can anyone help?

I have a created a relationship between my Reservation(prim key) and Insurance(for key) tables and imported into linq2sql and checked my automatically created c# files and sure enough i have reservation.MyFieldNames etc etc PLUS reservation.Insurance which is my relationship but reservation.Insurance i can’t see the fieldnames of Insurance – am i missing something?

Do i have to call a GetInsurances or something? I don’t see anything.. In fact Insurance is of type Linq.entityset???

Also i was hoping to create my reservation table (which was nice and easy) and then automatically “INJECT” a Insurance (i.e. 1 to many) from Ilist or something..

Is this not possible,

Any help really appreciated

p.s. I did create my automatically created c# dto files via T4 Toolbox but this shouldn’t make any difference. I just have a separate file for each entity..

Answer 1

Not 100% sure what you mean by “I don’t see anything”.

Assuming you have a Reservations table and an Insurance table which references the “reservations” – what kind of relationship is this? 1:1 ? 1:many ? Which way around?? Can you post a screenshot of your DBML designer surface? (upload it to http://www.tinypic.com and include the link as an image here in your question)?

The “Reservations” class will contain one instance of an “Insurance” (EntityRef<Insurance>) or a list (EntitySet) of “Insurance” objects (EntitySet<Insurance>) – depending on the nature of the relationship – and you should be able to navigate those in code, e.g.

string foo =  myReservation.Insurance.CustomerName; // or whatever 

You won’t see those on the designer surface – that’s just a link to another class somehwere on your design surface, right?

Same goes for the other way around – if the Insurance is associated with exactly one Reservation, you should be able (in code) to do:

 string bar = myInsuranceObject.Reservation.MyFieldName1; // or whatever

So it’s not quite clear to me which case you’re really referring to – can you elaborate on your question a bit more and make it clearer??

Based on the NerdDinner sample, I’ll try to elaborate. Check out the DBML design surface:

Here, you don’t see any of the properties used to move back and forth between the objects. But you do see that the “RSVP” class has a “DinnerID” foreign key which links it to the “Dinner” class. So this is a 1:n relationship: one Dinner has n RSVP’s, and every RSVP is for exactly one Dinner.

In your code, you see these created properties now – check out the RSVP class first:

You can see that the RSVP class has a EntityRef<Dinner> – a reference (link) to exactly one Dinner – that dinner that this RSVP is for.

On the other hand, the Dinner class has a whole list of RSVPs of all the geek planning to attend that dinner!

So in the Dinner class, you have a EntitySet<RSVP> – a whole list of attendees, which you can then navigate when you’re working with your Dinner class.

Does this make things a bit clearer?

Marc