Perrier Perrier - 3 months ago 9
C# Question

Change data in migration Up method - Entity Framework

I have added a new property into my existing model. It's a bool property with default value true. There are existing data in this table and I would like to set one specific row's new property to false right after creating the new field, in the Up method.

public override void Up()
{
AddColumn("dbo.RequestValidationErrors", "IsBreaking", c => c.Boolean(nullable: false));
using (Context ctx = new Context())
{
var validation = ctx.RequestValidationErrorSet.FirstOrDefault(x => x.WordCode == "RequestValidationError.MoreThanOneItemFound");
if (validation != null)
{
validation.IsBreaking = false;
ctx.SaveChanges();
}
}
}


This way EF throws an error during saying


System.InvalidOperationException: The model backing the
'Log4ProContext' context has changed since the database was created.
Consider using Code First Migrations to update the database


Is it possible to change the database here or should I do it elsewhere?

Answer

In the middle of a migration, it's better to use Sql() method to update database data.

Sql("UPDATE dbo.RequestValidationErrors SET IsBreaking = 0 WHERE WordCode = 'RequestValidationError.MoreThanOneItemFound'");

Also you should define the default value for the new column. So the solution should be something like this:

public override void Up()
{
    AddColumn("dbo.RequestValidationErrors", "IsBreaking", c => c.Boolean(nullable: false, default: true));
    Sql("UPDATE dbo.RequestValidationErrors SET IsBreaking = 0 WHERE WordCode = \"RequestValidationError.MoreThanOneItemFound\"");
}

Using a DbContext in the middle of it's migration is very ambiguous. What do you expect from the context? It has the after migration state in its models, but the database has the before migration state in the tables. So the model and database are not match. If you still insist on using DbContext in your code, disabling model checking might be the solution. You can disable model checking using:

Database.SetInitializer<Log4ProContext>(null);