CODEWITHSUNDEEP
c#entity-framework
Andriy Drozdyuk
Andriy Drozdyuk

Reputation: 61041

Identical entities generating different ids

How can I ensure that EF generates the same Id for the same occurence of an object?

E.g. if I have a class like:

class Foo{
    ICollection<Bar> Bar1;
    ICollection<Bar> Bar2;
}

If I create a new entity Foo and add a single instance of Bar (no id set) to both Bar1 and Bar2 - will it use the same Id for both or create a new one each time? E.g.:

var bar = new Bar();
var foo = new Foo{
   Bar1 = new List<Bar>(){ bar };
   Bar2 = new List<Bar>(){ bar };
}
context.SaveChanges();

Will Bar1 and Bar2 contain the same record bar with the same id?

UPDATE: What if I have two instances that are the same with respect to Equals and hash code?

var first = new Bar();
var second = new Bar();   /// first.equals(second )
var foo = new Foo{
   Bar1 = new List<Bar>(){ first };
   Bar2 = new List<Bar>(){ second };
}

or does EF not check for equals?

Upvotes: 2

Views: 87

Answers (1)

Dennis Traub
Dennis Traub

Reputation: 51634

Yes, Entity Framework will create one record for foo and one record for bar in the database. Since both lists contain the same instance of Bar the respective database entries will point to the same record.

Upvotes: 1

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