实体框架：在模型类中创建没有属性的数据库列

Question

Is it possible to tell Entity Framework via fluent mapping API to add a column to a specific table without a corresponding property in a model class?

Yes, I can achieve that by executing SQL script in a migration, but I would prefer to have this specified in a model configuration rather than in migrations.

Answer 1

I've been looking into this, admittedly to get around the problem of no native value-object(complex properties) handling until after release of EF core.

Shadow properties are a way of specifying that a migration generated from this context should add a column to the database. Specifically see my example:

// In DbContext-inheriting class:
protected override void OnModelCreating(ModelBuilder builder)
{
    // Ignore the model property that holds my valueobject -
    // (a complex type encapsulating geolocation latitude/longitude)
    var entityBuilder = builder.Entity<Item>()
        .Ignore(n => n.Location);

    // Add shadow properties that are appended to the table in the DB
    entityBuilder.Property<string>("Latitude");
    entityBuilder.Property<string>("Longitude");

    base.OnModelCreating(builder);
}

This generates the migration table-creation statement as follows:

migrationBuilder.CreateTable(
    name: "Items",
    columns: table => new
    {
        Key = table.Column<string>(nullable: false),
        Latitude = table.Column<double>(nullable: false),
        Longitude = table.Column<double>(nullable: false)
    },
    constraints: table =>
    {
        table.PrimaryKey("PK_Items", x => x.Key);
    });