![]() ![]() This command will cause Entity Framework Core to create the Items table in the database. The final step after creating one (or more) migrations is to actually apply them to the database: dotnet ef database update If you use a full-fledged SQL database, like SQL Server or MySQL, this won't be an issue and you won't need to do this (admittedly hackish) workaround. Comment out or remove any migrationBuilder.DropForeignKey lines in the Down method.Comment out or remove the migrationBuilder.AddForeignKey lines in the Up method.Until this problem is fixed, use this workaround: There are some limitations of SQLite that get in the way if you try to run the migration as-is. The Down method does the opposite: if you need to undo (roll back) the migration, the Items table will be dropped. ![]() ![]() Since you added a DbSet to the database context, Entity Framework Core will create an Items table (with columns that match a TodoItem) when you apply the migration. The Up method runs when you apply the migration to the database. Protected override void Down( MigrationBuilder migrationBuilder) Table.PrimaryKey( "PK_Items", x => x.Id) If you open your migration file, you'll see two methods called Up and Down:ĭata/Migrations/ _AddItems.cs protected override void Up( MigrationBuilder migrationBuilder) You can see a list of migrations with dotnet ef migrations list. Your new AddItem migration is prefixed with a timestamp when you create it. The first migration file (with a name like 00_CreateIdentitySchema.cs) was created and applied for you way back when you ran dotnet new. If you open up the Data/Migrations directory, you'll see a few files: These commands must be run from the project root directory (where the Program.cs file is). If you get an error like No executable found matching command "dotnet-ef", make sure you're in the right directory. This creates a new migration called AddItems by examining any changes you've made to the context. Since the context now includes a set (or table) that doesn't exist in the database, you need to create a migration to update the database: dotnet ef migrations add AddItems In the previous chapter, you added an Items set to the context. With migrations, you have a full history of modifications like adding or removing columns (and entire tables). They make it possible to undo (roll back) a set of changes, or create a second database with the same structure as the first. Migrations keep track of changes to the database structure over time. ![]()
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