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]

tschmit · Accepted Answer · 2015-09-08 09:07:28Z

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 8, 2015 at 9:07

tschmit

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5 Comments

Simone Over a year ago

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

tschmit Over a year ago

do you have a __migrationHistory table in your database ?

tschmit Over a year ago

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<MyContext>(null); stackoverflow.com/questions/10623260/…

Simone Over a year ago

Strange, I have solved deleting the __migrationHistory and launching the following command: Update-Database -verbose -StartUpProjectName MyProject int the Package Manager Console

tschmit Over a year ago

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.

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