EF5 Code First: Detect if it creates a database so I can run ALTER statements

Question

I am new with Entity Framework 5. Our team is using Code First workflow.

Before I'll start with my main question, let me first show you what I have tried ^{( the ultimate comment of all time :D )} .

public class MyDBContext : CDBContext
{
    public MyDBContext() : base(connString) { }

    public MyDBContext(string connStr) : base(connStr) { }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        // removes some conventions
        modelBuilder.Conventions.Remove<ManyToManyCascadeDeleteConvention>();
        // ........

        // model configurations which contains mappings
        modelBuilder.Configurations.Add(new AccountConfiguration());
        // ........

        // calls base OnModelCreating
        base.OnModelCreating(modelBuilder);
    }

    // list of all Entity
    public DbSet<Account> Account { get; set; }
}

MyDBContext is the class I have created that inherits from CBDContext that contains override methods and which also inherits from DBContext . One of the problems I have encountered is that entity framework doesn't handle field uniqueness. I have already read the article on Configuring/Mapping Properties and Types with the Fluent API on their site and I can't find any configuration to set a property into unique.

So what I did in order to set the field unique is to manually run several ALTER sql statements during creation,

using (MyDBContext _context = new MyDBContext(connString))
{
    if (_context.Database.CreateIfNotExists()) 
    {
        _context.Database.ExecuteSqlCommand("ALTER TABLE Account ADD CONSTRAINT UQ_Account_AccountNumber UNIQUE(AccountNumber)");
        _context.Database.ExecuteSqlCommand("ALTER TABLE Account ADD CONSTRAINT UQ_Account_GUID UNIQUE(GUID)");
        // .... more on this in the following lines ...
    }
}

My Questions:

1. Am I right that entity framework don't have any configuration or data annotations to set the field unique ?
2. Is there a way to detect or know during runtime if EF creates a database or not so I can move or hide this statement if (_context.Database.CreateIfNotExists()) somewhere to an available method that can be overriden?

What I really want is to remove if (_context.Database.CreateIfNotExists()) from the using statemnt and put it somewhere else or inside MyDBContext so my code will look like this,

using (MyDBContext _context = new MyDBContext(connString))
{
    Account _acc = new Account()
    // ...Account properties ...

    _context.Account.Add(_acc);
    _context.SaveChanges();
}

Thanks.

Answer 1

You should take a look at Code First Migrations , more specific at the Data Motion / Custom SQL and later sections - this is might the way to achieve your desired result. Your migration class can look like this:

public partial class AddUniqueConstrains : DbMigration
{
    public override void Up()
    {
        Sql("ALTER TABLE Account ADD CONSTRAINT UQ_Account_AccountNumber UNIQUE(AccountNumber)");
        Sql("ALTER TABLE Account ADD CONSTRAINT UQ_Account_GUID UNIQUE(GUID)");
    }

    public override void Down()
    {
        Sql("ALTER TABLE Account DROP CONSTRAINT UQ_Account_AccountNumber UNIQUE");
        Sql("ALTER TABLE Account DROP CONSTRAINT UQ_Account_GUID");
    }
}

You can also explore other options described in answers to this question: Unique Constraint in Entity Framework Code First

Answer 2

If you don't use (or cannot use) EF migrations you can use custom initializer as mentioned in this answer . The custom initializer will execute a Seed method after creating the database = only once when database doesn't exist. If you need to incrementally develop the database initializer itself will not help you (that is what migrations are for).