Generating Entity Keys

Question

I have run into my first dissapointment with Entity Framework 4. It turns out that SQL CE, when used with EF4, does not support autogenerated primary keys. I get a System.Data.UpdateException from OnjectContext.SaveChanges() with this message:

Server-generated keys and server-generated values are not supported by SQL Server Compact.

So, now I have to manually generate keys for my entities. Assuming I want to use auto-incremented integer keys, what is the best way to go about generating and keeping track of the keys when using Entity Framework? Thanks for your help.

score 4 · Accepted Answer · answered Mar 19 '10 at 23:07

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At the bottom of the link in your question is a suggested solution. See SQL Compact, Identity Columns and Entity Framework perhaps you might want to implement an extension method like the one outlined.

answered Mar 19 '10 at 23:07

DaveB

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Good answer, but unfortunately, the code on the linked page only works for unfiltered entity sets, since the extension method returns the max id in the entity set. So, I ended up using a GUID as the entity key. I created a partial class for each entity with this constructor code: this.ID = Guid.NewGuid() – David Veeneman Mar 20 '10 at 22:30

score 0 · Answer 2 · edited Dec 23 '11 at 00:36

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I don't think David's idea is a good idea, however, I have no choice. Maybe CE will support autogenerated primary keys in next version.

edited Dec 23 '11 at 00:36

Dan McClain

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answered Jun 09 '10 at 03:13

gary

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Actually, SQL Compact does support autogenerated keys--apparently, it's EF4 that doesn't support autogenerated keys from SQL Compact. The blog post linked in my original question explains the problem. – David Veeneman Jul 23 '10 at 15:05

Generating Entity Keys

2 Answers2

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