I'm trying to use CF to build a model for an existing database. I have a column in which I forgot to set a sane default value. And rather than compromise the purity of the initial migration by changing it, I just figured I'd create another migration (that's what migrations are for, right? :)
public override void Up()
{
AlterColumn("Config", "DefaultTaxPerDollar", c => c.Decimal(nullable: false, precision: 19, scale: 5, defaultValue: 0.087m));
}
public override void Down()
{
AlterColumn("Config", "DefaultTaxPerDollar", c => c.Decimal(nullable: false, precision: 19, scale: 5, defaultValue: 0.0m));
}
But this produces Column already has a DEFAULT bound to it.
error from the SQL Server.
How does one change a default value using CF migrations? Or, how does one simply remove a default value (and subsequently re-create it with a different value)?
Edit:
Here is the SQL generated:
ALTER TABLE [Config] ADD CONSTRAINT DF_DefaultTaxPerDollar DEFAULT 0.087 FOR [DefaultTaxPerDollar]
ALTER TABLE [Config] ALTER COLUMN [DefaultTaxPerDollar] [decimal](19, 5) NOT NULL
I think I may have found a solution, to use the Sql()
method with some complex SQL inspired by this post. The problem stems from the fact that SQL Server uses constraints to implement defaults (OH! how I miss MySQL!) with a generated name for the constraint. So the Code First team could not simply change or remove/re-create the default value easily.
See Question&Answers more detail:
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