efcore: AddColumn migrations created with bad default

Hope I’m not reporting a dup here.

Testing with SqlServer, I’ve added this property to my model:

builder.Entity<Blog>().Property(b => b.SomeProp).ValueGeneratedOnAdd();

Generating a migration creates the following code:

migrationBuilder.AddColumn<int>(
    name: "SomeProp",
    table: "Blogs",
    nullable: false,
    defaultValue: 0)
    .Annotation("SqlServer:ValueGenerationStrategy", SqlServerValueGenerationStrategy.IdentityColumn);

Note the defaultValue: 0, which I didn’t specify in the model in any way. Note also that if the column is defined when creating the table, the correct CreateTable migration is generated:

SomeProp = table.Column<int>(nullable: false)
    .Annotation("SqlServer:ValueGenerationStrategy", SqlServerValueGenerationStrategy.IdentityColumn),

This causes an issue with Npgsql (https://github.com/npgsql/Npgsql.EntityFrameworkCore.PostgreSQL/issues/68) since the default value is examined in the migration decision process.

About this issue

Original URL
State: closed
Created 8 years ago
Comments: 28 (21 by maintainers)

Most upvoted comments

@rowanmiller, note the discrepancy between what happens if the non-nullable column is present when the table is created, and when it’s added later (i.e. between the CreateTable migration and the AddColumn migration) - in the first case there’s no default, in the second there is. This is the part that bothers me most; if you always set the CLR default as the column default it would at least be consistent (although still wrong IMHO).

Again, I get the reasoning behind the default - when adding a column to an existing table there’s the issue of existing rows, which doesn’t exist when creating a new table. But that seems to be a detail; it seems that the database schema for a given model should be the same regardless of the history/migration path taken to reach it.

roji on Jul 15, 2016