How to get parent entity key?

Question

I use EntityFramework and in my edmx file I have two tables mapped:

Customers column: Id PK

and Orders columns: Id PK CustomerId FK

which are associated.

When I take Order object there IS Customer property but I can't see CustomerId property. I used to work with L2SQL and I expected to see CustomerId but EF somehow hides it.

Be aware that relations with and without a foreign key property are handled differently: http://stackoverflow.com/questions/5281974/code-first-independent-associations-vs-foreign-key-associations/5282275#5282275 — Ladislav Mrnka, Apr 13 '11 at 17:41

score 2 · Accepted Answer · answered Apr 13 '11 at 14:41

2

the Add Association dialog in the EF edmx designer allows you to specify (via a checkbox) whether or not you want to have a "Foreign Key" (and/or a Navigation Property) created for the association. did you make sure it's checked?

answered Apr 13 '11 at 14:41

AbdouMoumen

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I was just going to write that too ;) Now I only paste the link I still have in my clipboard in the comment here: http://blogs.msdn.com/b/msdnforum/archive/2010/05/07/foreign-key-association-in-entity-framework-4.aspx There is a screenshot of the wizard in VS2010. It's worth to be noted that this is an EF 4 option which isn't available EF 1 (.NET 3.5SP1). – Slauma Apr 13 '11 at 14:45
I can't check it: This functionality is not available in the target framework ... (3.5) – jlp Apr 13 '11 at 14:48
@jpl: Indeed, it doesn't exist in EF 1 (.NET 3.5). You have to load the customer then to get the foreign key. Or upgrade to .NET 4 if you can. – Slauma Apr 13 '11 at 14:50
yeah, that was added in EF 4 (check @Slauma's link) – AbdouMoumen Apr 13 '11 at 14:52

score 0 · Answer 2 · answered Apr 13 '11 at 14:28

0

Inside the Customer property, there should be a CustomerId property.

So try..

myOrderObject.Customer.CustomerId

answered Apr 13 '11 at 14:28

Travyguy9

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This might force EF to load the customer object (if you have enabled lazy loading). If you want only the ID, this could be a bad idea ... – MartinStettner Apr 13 '11 at 14:31
I can't use myOrderObject.Customer.CustomerId because myOrderObject.Customer can be null (yes!) – jlp Apr 13 '11 at 14:38
Then add a null check. If it isn't null, use the object. – Travyguy9 Apr 13 '11 at 14:39
I wrote '2 tables' for simplicity, actually it's more complicated and I apparently must use couple 'Include' in query. I think I stay with L2SQL then – jlp Apr 13 '11 at 14:55

score 0 · Answer 3 · answered Apr 13 '11 at 14:29

How exactly is the id column in the order table named? Usually the EF-Designer should create a property for each column in the database table. Have a look at the "Mapping details" page (which you can open in the context menu of the EF designer) to see if (and to which property) the column is mapped.

How to get parent entity key?

3 Answers3