![]() ![]() ![]() Back up your database, in case something goes wrong.This is sometimes called "squashing", and involves some manual work: It's also possible to reset all migrations and create a single one without losing your data. This can be easily done by deleting your Migrations folder and dropping your database at that point you can create a new initial migration, which will contain your entire current schema. In some extreme cases, it may be necessary to remove all migrations and start over. To do this, add a migration without making any model change an empty migration will be generated, which you can then populate with raw SQL operations.įor example, the following migration creates a SQL Server stored procedure: ('CREATE PROCEDURE nvarchar(50) Raw SQL can also be used to manage database objects that EF Core isn't aware of. SET FullName = FirstName + ' ' + LastName To transfer the data from the old columns, we rearrange the migrations and introduce a raw SQL operation as follows: migrationBuilder.AddColumn( The migration generated by EF Core will be the following: migrationBuilder.DropColumn(Īs before, this would cause unwanted data loss. For example, we may want to replace existing FirstName and LastName properties with a single, new FullName property. ![]() While renaming a column can be achieved via a built-in API, in many cases that is not possible. If you see that warning, be especially sure to review the migrations code for accuracy. The migration scaffolding process warns when an operation might result in data loss (like dropping a column). To rename a column, replace the above generated migration with the following: migrationBuilder.RenameColumn( If the above migration is applied as-is, all your customer names will be lost. For example, if you rename a property from Name to FullName, EF Core will generate the following migration: migrationBuilder.DropColumn(ĮF Core is generally unable to know when the intention is to drop a column and create a new one (two separate changes), and when a column should be renamed. One notable example where customizing migrations is required is when renaming a property. ![]() While EF Core generally creates accurate migrations, you should always review the code and make sure it corresponds to the desired change in some cases, it is even necessary to do so. You can also change the namespace independently of the directory using -Namespace. Alternatively, you can specify the directory at generation time as follows: New migrations are created as siblings of the last migration. You are free to move Migrations files and change their namespace manually. The timestamp in the filename helps keep them ordered chronologically so you can see the progression of changes. Used to determine what changed when adding the next migration. M圜ontextModelSnapshot.cs-A snapshot of your current model.XXXXXXXXXXXXXX_-The migrations metadata file.Contains the operations necessary to apply the migration (in Up) and to revert it (in Down). XXXXXXXXXXXXXX_AddCreatedTimestamp.cs-The main migrations file.Three files are added to your project under the Migrations directory: For example, you might choose a name like AddBlogCreatedTimestamp if the change is a new CreatedTimestamp property on your Blog entity. The migration name can be used like a commit message in a version control system. I've tried these two things and they both result in now() being executed at the time of the statement.Dotnet ef migrations add AddBlogCreatedTimestamp The first event always happens when the row is created, so I want the array to be instantiated with an initial default value. I want to have a timestamp array which tracks a series of events. ![]()
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