Clash Royale CLAN TAG

How can I keep custom data annotations/fluent api when I scaffold -force in ef core 2.0?

I'm using EF core 2 with existing database.
Used Scaffold-DbContext command to reverse engineer classes. This worked fine.
Even Fluent API has pulled through correct database field constraints etc. e.g.

. . . .
modelBuilder.Entity<FsReport>(entity =>
{
entity.Property(e => e.Bcclist)
.IsUnicode(false)
.HasDefaultValueSql("('')");

entity.Property(e => e.Cclist)
.IsUnicode(false)
.HasDefaultValueSql("('')");
. . . .


Problem is for 1 field I need to add a custom data annotation. If I add this, then as soon as I rerun Scaffold-DbContext -force command (e.g. if database schema change) then the annotation will be overwritten and removed.

Is there anything I can do to avoid this? I tried putting it in a different partial class of the same name but got a 'The type already contains a definition for.... error'

Many thanks for any help.

2 Answers
2

No. If you insist on sticking with running Scaffold-DbContext (Database first) you will need to add your change back in afterwards. The best way to go forward is to read up on and implement Entity Framework Core Migrations (Code first).

Scaffold-DbContext

I have a similiar situation where I wanted to re-generate the scaffold based on "outside-my-control" DB changes and maintain my custom DbContext edits. I solved this by sub-classing the generated DbContext (referring to it here as ScaffoldDbContext). In the subclass (called ScaffoldNavigationDbContext) I call the base.OnModelCreating before making my custom edits on the modelBuilder.

DbContext

DbContext

ScaffoldDbContext

ScaffoldNavigationDbContext

base.OnModelCreating

modelBuilder

The scaffolding code generates the entity classes as partial so I take advantage and introduce those navigation properties in my classes....separate from the scaffold generated classes. For example, below is my code that will 'survive' a new scaffold generation. There may be caveat's to this but I'm unaware of them and for my simple use-case, it works.

public partial class ScaffoldNavigationDbContext : ScaffoldDbContext {

public ScaffoldNavigationDbContext (DbContextOptions options) : base(options) { }

protected override void OnModelCreating(ModelBuilder modelBuilder) {
base.OnModelCreating(modelBuilder);

modelBuilder.Entity<CertMaster>(entity => {
entity.HasMany(x => x.CertTrans).WithOne(x => x.CertMaster).HasPrincipalKey(x => x.CertId);
});
}
}

public partial class CertMaster {
public List<CertTrans> CertTrans{ get; set; }
}

public partial class CertTrans {
public CertMaster CertMaster { get; set; }
}


By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.