Creating Entity Framework Table That Does Not Have Auto Increment Id

Question

Using Entity Framework SQL-Server-CE I have created a table like this:

class Era {
    public long Id { get; set; }
    [Index(IsUnique=true), Required]
    public long Code { get; set; }
    public string Name { get; set; }
    public long StartDate { get; set; }
    public long EndDate { get; set; }
}

Whenever I try to insert into it using Entity Framework, the Id field of the Era object is ignored and an auto incremented Id is inserted.

How can I make the Id field not to use the auto incremented value, and use the given value instead, using annotations preferably.

score 6 · Answer 1 · answered Jun 08 '15 at 09:38

6

[DatabaseGenerated(DatabaseGeneratedOption.None)]

This ensures that EF will not try and change the values and will simply insert them with the rest of the data.

here is detail description about it link

answered Jun 08 '15 at 09:38

sm.abdullah

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The link is about switching identity insert on. You don't need to do that if you create a primary key that is not database generated. – Colin Jun 08 '15 at 13:16

score 2 · Answer 2 · answered Jun 08 '15 at 09:33

2

I think you need:

[DatabaseGenerated(DatabaseGeneratedOption.None)]

The default is that the database generates a value, so you need to explicitly turn that off.

answered Jun 08 '15 at 09:33

Dennis_E

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adding that annotation and trying to insert results in this exception: System.Data.SqlServerCe.SqlCeException: The column cannot be modified. [ Column name = Id ] – raven Jun 08 '15 at 09:41
@raven as I mention see this link http://blog.robertobonini.com/2014/10/09/entity-framework-with-identity-insert/ – sm.abdullah Jun 08 '15 at 09:59
1

@raven After adding that annotation you must recreate the database – ErikEJ Jun 08 '15 at 10:15
@sm.abdullah i'm trying that out right now, but in that example an sql connection string is required, but i'm using sql compact and i have no idea what to use there. – raven Jun 08 '15 at 10:20
@ErikEJ yes i have updated the database using package manager console – raven Jun 08 '15 at 10:21
@raven updating the database does not necessarily drop and re-create the table or the database http://stackoverflow.com/a/18917348 – Colin Jun 08 '15 at 13:19
@Colin i did not know that. are you saying that if you recreate the table you wont need to do the stuff i've done in my answer? – raven Jun 09 '15 at 13:52
Yes, and that is why @ErikEJ said you should recreate the database. If the table is empty that's not a problem. If you need to fix up data you could use a custom migration: http://romiller.com/2013/04/30/ef6-switching-identity-onoff-with-a-custom-migration-operation/ – Colin Jun 09 '15 at 16:14

raven · Accepted Answer · 2015-06-21T11:02:09.467

0

so this is the answer that i was looking for:

if you want to have a table with non-auto increment id in entity framework; you need to first backup the data, drop the table(this can be done by commenting the relevant DbSet in your DbContext class), adding the annotation [DatabaseGenerated(DatabaseGeneratedOption.None)] then migrating and updating database.

edited Jun 21 '15 at 11:02

answered Jun 08 '15 at 10:54

raven

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Your root problem is that the column is IDENTITY when it should be `DatabaseGeneratedOption.None`. You have found an interesting workaround, but really you should change the column. You are correct about needing to do more than add a data annotation if you have already created the table....http://stackoverflow.com/a/18917348 – Colin Jun 08 '15 at 13:13

Creating Entity Framework Table That Does Not Have Auto Increment Id

3 Answers3