circular dependency in entity framework

Question

Is it possible to save model which has got circular dependency ?

I denormalized my Database:

User
--------
UserId
UserName
LastOrder   - fk to last order


Order
-------
OrderId
OrderName
UserId
OrderDate

Is it possible to save sth like this using entityFramework?

what should I change to make it work cause now I have got error:

Unable to determine a valid ordering for dependent operations. Dependencies may exist due to foreign key constraints, model requirements, or store-generated values.

Isn't the last order the first order matching the user id sorted by time descending? I think you could do without the FK if you had an index on user id and order date. — tvanfosson
– tvanfosson, Commented Nov 29, 2010 at 13:45
It is simplified, In my real app I want exactly that reference, is it possible to achieve ? — gruber
– gruber, Commented Nov 29, 2010 at 13:46
id have 1 FK reference or the other, I wouldn't have both as it seems counter intuitive — stack72
– stack72, Commented Nov 29, 2010 at 13:47
Order has got FK to user -> natural user has got fk to Order -> not natural but useful in my case. Is it possible to save sth like that ? thanks for help — gruber
– gruber, Commented Nov 29, 2010 at 13:53

Community · Accepted Answer · 2017-05-23 10:32:38Z

49

I had a table that had a relationship to itself and i was getting the same error. Turns out the foreign key has to be nullable. Same table relationship in Entity Framework I hope this saves someone more time than I wasted.

edited May 23, 2017 at 10:32

CommunityBot

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answered Dec 15, 2010 at 2:48

tkerwood

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4 Comments

Adam Oren Over a year ago

Saves me a lot of time also. Thanks! Does anyone knows why this happens? why does the foreign key must be nullable?

tkerwood Over a year ago

@Adam - I am guessing it is to allow you to insert the first row into the table. (there will be no other records to link to)

Nick Sarabyn Over a year ago

Thanks for the answer. I had to change my relationship from 1 to many to 0..1 to many to prevent a "Multiplicity is not valid" error after I set my foreign key to nullable but everything is running smoothly now.

Marc.2377 Over a year ago

Well, this won't work for circular references which is what was asked, but good to know nevertheless.

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