I am looking into Migrations in an effort to clean up our deployment processes. The less manual intervention required when pushing a change to production the better.
I have run into 3 major snags with the migrations system. They are show stoppers if I can not figure out a clean way around them.
1. How do I add Seed data per migration:
I execute the command "add-migration" which scaffolds a new migration file with Up and Down functions. Now, I want to automatically make changes to the data with both Up and Down changes. I don't want to add the Seed data to the Configuration.Seed method as this runs for all migrations which ends in all sorts of duplication problems.
2. If the above is not possible, how do I avoid duplications?
I have an enum that I loop through to add the values to the database.
foreach(var enumValue in Enum.GetValues(typeof(Access.Level))) { context.Access.AddOrUpdate( new Access { AccessId = ((int)enumValue), Name = enumValue.ToString() } ); } context.SaveChanges();
Even though I am using AddOrUpdate, I still get duplicates in the database. The above code brings me to my 3rd and final problem:
3. How can I seed Primary Keys?
My enumerable with the above code is:
public class Access { public enum Level { None = 10, Read = 20, ReadWrite = 30 } public int AccessId { get; set; } public string Name { get; set; } }
I am specifying the values that I want as my primary key, but Entity Framework seems to ignore it. They still end up being 1,2,3. How do I get it to be 10,20,30?
Are these limitations of EF at the moment or are they intentional constraints to prevent some other kind of catastrophe I am not seeing?
Seed Data in Entity Framework Core So as soon as we execute our migration files to create and configure the database, we want to populate it with some initial data. This action is called Data Seeding. So, we are using the HasData method to inform EF Core about the data it has to seed.
Sql("Insert ...")
. See the note halfway down this page: how to insert fixed data [DatabaseGenerated(DatabaseGeneratedOption.None)]
attributeI think this is a good explanation of Initializer and Seed methods
Here is an example of how to use the AddOrUpdate method:
foreach(var enumValue in Enum.GetValues(typeof(Access.Level))) { context.Access.AddOrUpdate( x => x.Name, //the natural key is "Name" new Access { AccessId = ((int)enumValue), Name = enumValue.ToString() } ); }
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