I have in database table Gifts with records, for example:
Id: 1, Name: A
Id: 2, Name: B
Id: 3, Name: C
In IEnumerable<Gift> gifts
I have elements from user after modification, for example:
Id: 1, Name: A_update
Id: 3, Name: C_update
Id: 0, Name: D_new
Now I would like records that exist in the database that don't exist in the list - so in this example it should be one record:
Id: 2, Name: B
How can I do that because below code doesn't work:
List<Gifts> result = db.Gifts.Where(x => !gifts.Select(y => y.Id).Contains(x.Id)).ToList();
Unable to create a constant value of type 'MyProject.Models.Gift'. Only primitive types or enumeration types are supported in this context.
This is a limitation of Entity Framework. In only supports using some specific data types in the expressions.
If you use Entity Framework 4.0 or later you can use this workaround:
int[] giftIds = gifts.Select(y => y.Id);
List<Gifts> result = db.Gifts.Where(x => !giftIds.Contains(x.Id)).ToList();
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