未调用种子方法，实体框架 6

Question

I have a DatabaseInitializer class

public class DatabaseInitializer : CreateDatabaseIfNotExists<DatabaseContext>
{
    protected override void Seed
        (
        DatabaseContext databaseContext
        )
    {
        // Seed the hash methods.
        var defaultHashMethod = new HashMethod
        {
            Description = "Default",
            CreateDate = DateTime.Now
        };

        databaseContext.HashMethod.Add(defaultHashMethod);

        databaseContext.SaveChanges();
    }
}

In my DatabaseContext class I set the initializer

public DatabaseContext() : base("DatabaseContext")
{
    InitializeDatabase();
}

private void InitializeDatabase()
{
    Database.SetInitializer(new DatabaseInitializer());
    if (!Database.Exists())
    {
        Database.Initialize(true);
    }            
}

As far as I can understand the seed method is only invoked once you perform an operation such as a query. My database is created successfully and I'm querying the table, but the seed method is never called.

Update:

It seems like the problem is caused because of a class that is inheriting from my DatabaseContext class, when using this class to perform database operations, the seed method is not called. When using my DatabaseContext class, everything works as expected

public DbSet<TestEntity> TestEntity { get; set; }

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
}

Answer 1

您需要从Package Manager Console调用Update-Database 。

Answer 2

The only way I could get this to work was to call the seed method myself

Here are the methods for my DatabaseContext class

 public DatabaseContext() : base("DatabaseContext")
 {
    InitializeDatabase();
 }

 public DatabaseContext(string connectionString) : base(connectionString)
 {
     Database.Connection.ConnectionString = connectionString;
     InitializeDatabase();
 }

 protected override void OnModelCreating(DbModelBuilder modelBuilder)
 {
     modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
 }

Here I changed my InitializeDatabase method from

private void InitializeDatabase()
{
    Database.SetInitializer(new DatabaseInitializer());
    if (!Database.Exists())
    {
        Database.Initialize(true);
    }            
}

to

protected virtual void InitializeDatabase()
{
    if (!Database.Exists())
    {
        Database.Initialize(true);
        new DatabaseInitializer().Seed(this);
    }            
}

Answer 3

to get Seed method to be called when you are not using AutomaticMigration , you should use MigrateDatabaseToLatestVersion initializer for your code-first database.
like this:

Database.SetInitializer(new MigrateDatabaseToLatestVersion<YourContext,YourConfiguration>());  

this way, Seed method will be called every time the migration is done successfully.

Answer 4

This can happen if your Update-Database command does not run successfully, and this does not necessarily mean that it errors out. There might be changes that EF recognizes as "outstanding" that need to be added to a migration.

Try calling "Add-Migration {migrationNameHere}" and then try "Update-Database" again.

Answer 5

我遇到了这个问题，问题是我的 Context 构造函数没有使用与 web.config 中相同的名称。

Answer 6

If you are using Code-First then you can populate the data when the application runs for the first time.

• Create a DbInitializer

   public class MyDbInitializer : IDatabaseInitializer<MyDbContext> { public void InitializeDatabase(MyDbContext context) { if (context.Database.Exists()) { if (!context.Database.CompatibleWithModel(true)) { context.Database.Delete(); } } context.Database.Create(); User myUser = new User() { Email = "a@b.com", Password = "secure-password" }; context.Users.AddOrUpdate<User>(p => p.Email, myUser); context.SaveChanges(); } }

• Register this DbInitializer in your Global.asax.cs Application_Start method

   Database.SetInitializer(new My.namespace.MyDbInitializer());

Answer 7

My seed was not being executed either. However, it was because I added a column to a model that I had no intention of using in my actual database and forgot to use the [NotMapped] annotation.

    [NotMapped]
    public string Pair { get; set; }

There was no error message relating to this being the cause at all. Just a null reference to my repository obj when I tried to query data that should have been there.