Entity Framework COde FIrst migration existing table

Question

I have a (strange) situation. I am using Entity Framework Code First but I have to attach to an existing Database.

I do not have to map every single table of the database in my object model. So I would like to migrate single Tables, whenever I need it. I try to explain better. My database have about 100 tables, but I need to map in my model just 3 or 4. I have created my classes in c# and now I would like to map this classes with the tables I need.

Is it possible to do it? Do I have to do a migration?

UPDATE Here my class:

public class PricePlan
{
    public Guid Id { get; set; }
    public String Name { get; set; }
    public Double ActivationPrice { get; set; }
}

Here the context:

public class PublicAreaContext : DbContext 
{
    public DbSet<PricePlan> PricePlans { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<PricePlan>()
            .HasKey(pp => new { pp.Id });

        base.OnModelCreating(modelBuilder);
    }
}

Here the table:

ALTER TABLE [dbo].[PricePlan](
    [Id] [uniqueidentifier] NOT NULL,
    [Name] [varchar](50) NULL,
    [ActivationPrice] [decimal](5, 2) NULL,
    ... //Other columns
 CONSTRAINT [PK_Price_Plans] PRIMARY KEY CLUSTERED 
(
    [Id] 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]

score 2 · Answer 1 · answered Sep 08 '15 at 09:07

2

possible: yes

migration: no. If you need migration you may have problem as in this case you haven't the __migrationHistory table (as the db is "existing" by opposite to "created by EF").

But the answer is definitively yes.

Create your classes, create a DbContext comprising DbSet, "et voilà".

answered Sep 08 '15 at 09:07

tschmit007

7,559
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It's not enough... When I try to do an insert to the table of database, I obtain this message: `The model backing the 'PublicAreaContext' context has changed since the database was created. Consider using Code First Migrations to update the database`.. Give me 2 minutes and I update the question – Simone Sep 08 '15 at 09:35
1

do you have a __migrationHistory table in your database ? – tschmit007 Sep 08 '15 at 09:36
1

that means that the database is not "existing". Don't you have access to the context class corresponding to the Db ? Otherwise you may use `Database.SetInitializer(null);` http://stackoverflow.com/questions/10623260/how-can-i-disable-model-compatibility-checking-in-entity-framework-4-3 – tschmit007 Sep 08 '15 at 09:40
Strange, I have solved deleting the `__migrationHistory` and launching the following command: `Update-Database -verbose -StartUpProjectName MyProject` int the `Package Manager Console` – Simone Sep 08 '15 at 09:47
Not strange: DANGEROUS. There is an historical context accessing the database (the one which created the __migrationHistory table). Now this context, and the app depending on it may become instable. – tschmit007 Sep 08 '15 at 10:01

Entity Framework COde FIrst migration existing table

1 Answers1