Entity Framework: Generating specific table if doesn't exist?

Question

I have some old tables which I have added them to the project by reverse engineering to use them as code first.

Something like this:

public class User
{
    public string Name { get; set; }
    public int Id { get; set; }
}

public class Profile
{
    [Key, ForeignKey("User")]
    public int  Id { get; set; }
    public string Name { get; set; }

    public virtual User User { get; set; }
}

public class EFDbContext : DbContext
{
    public DbSet<User> Users{ get; set; }
    public DbSet<Profile> Profiles { get; set; }
}

Here if my old table User was exist then Entity Framework doesn't create other tables such as Profile table.

My Question How can I specify which table should be created if doesn't exist?

Are you saying that if the table "User" exists, then EF doesn't create the tables (like "Profile") that you want it to, that don't exist yet? I'm not sure what you mean by "which table shouldn't be manipulated". — Ann L.
– Ann L., Commented Jan 26, 2013 at 17:04
Yes that is what I say or what I see, at least. my last sentence was incorrect, sorry. — Blazi
– Blazi, Commented Jan 26, 2013 at 17:09
@Blazi , Are you mixing DB first with Code first or is your project purely Code-first to DB sync? — Dave Alperovich
– Dave Alperovich, Commented Jan 26, 2013 at 18:45
Here it is code-first ( I created code first classes from existing database by entity framework plugin).. But I have also tried mixing code-first with data base first. didn't success with both of the approaches. — Blazi
– Blazi, Commented Jan 26, 2013 at 18:59

ARs · Accepted Answer · 2013-09-17 18:09:08Z

6

I had the same problem. And I solved it using the Sql method of the DbMigration class. Something like this

 public partial class userToTblUsersMapping : DbMigration
{
    public override void Up()
    {
        this.Sql(@"IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[tblUsers]') AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[tblUsers](
[UserID] [varchar](50) NOT NULL,
[UserIDNo] [int] IDENTITY(1,1) NOT NULL,
CONSTRAINT [PK_tblUsers] PRIMARY KEY CLUSTERED 
([UserID] ASC)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF,            ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
END"
    }
   public override void Down()
   {
      DropTable("dbo.tblUsers");
   }
}

answered Sep 17, 2013 at 18:09

ARs

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1 Comment

IbrarMumtaz Over a year ago

Is this still the only way to do this in 2016? Surely someone has found a nice way of doing a check before creating a new table?

Community · Accepted Answer · 2020-06-20 09:12:55Z

4

Have you checked this answer?

EF4 Code First create new table

Unless you drop and re-created you full database, I don't think it's possible.

Setting an Initialization Strategy

In the next section we are going to start changing our model which in turn means the database schema needs to change as well. Currently there is no ‘out of the box’ solution to evolve your existing schema in place. Database evolution is something we are currently working on and a sample of the direction we are heading is provided in a recent design blog post.

There is however the opportunity to run some custom logic to initialize the database the first time a context is used in an AppDomain. This is handy if you want to insert seed data for test runs but it’s also useful to re-create the database if the model has changed. In CTP5 we include a couple of strategies you can plug in but you can also write custom ones.

Add a using statement for System.Data.Entity.Database at the top of Program.cs

using System.Data.Entity.Database;

For the walkthrough we just want to drop and re-create the database whenever the model has changed, so at the top of the Main method in my Program class I’ve added the following code

DbDatabase.SetInitializer<ProductContext>(
new DropCreateDatabaseIfModelChanges<ProductContext>());

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Jan 26, 2013 at 18:55

Androiderson

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1 Comment

Devesh Khandelwal Over a year ago

Thanks. I was at the starting phase of my application, and I did drop the database and it just worked.

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