Basically my existing EF Core database is created via EnsureCreatedAsync() without any migrations, and now I have to create a new single table which is in DbSet<Model> inside the DbContext class. How do I do this? I've tried the following
RelationalDatabaseCreator databaseCreator =
(RelationalDatabaseCreator)_dbContext.Database.GetService<IDatabaseCreator>();
but it only contains methods for creating an entire database. Also my existing database already contains information that I wont be able to just drop.
Related
I'm using an existing database and I have mapped one of the tables as an entity (as i needed to map a foreign key).
So when it comes to initialising this database I would like EF to ignore this entity since it already exists.
How would I go about doing this?
You should create an empty migration as the first migration with the -IgnoreChanges flag to allow Entity Framework to get a snapshot of the existing database.
So out of the gate use:
Add-Migration InitialMigration -IgnoreChanges
and that will create a blank migration but it will update the Entity Framework metadata allowing the existing tables to exist and not be touched by migrations.
Also to be mentioned that the naming conventions that Entity Framework expects and your database schema may differ. You may need to manually setup the foreign keys using the Fluent API.
I didnt check with EF 6 specifically, but I think default EF behavious is that when the database exists, then it presume all model be ready and therefore will create no tables. If you want your initialization code to create tables with code first, use initialization code for prepare data. Look here :
http://www.entityframeworktutorial.net/code-first/seed-database-in-code-first.aspx
I need to add a new column / property to my database and my model without EF Code First dropping my database.
Is there a way to manually map a column to property so EF would not drop my database?
Update:
Got it to work by following this post on SO.
https://stackoverflow.com/questions/6049135/manually-editing-database-in-code-first-entity-framework
Basically you just need to:
Manually add the column to your database
Manually add the property to your model
Disable any database initializer in your DataContext
As long you're using anything beyond EF 4.3, you would use Migrations to do so. You can't do it manually because EF relies on the model that is stored in order to best do the mapping to SQL. When you make a change it refreshes the model. Any attempt to add something without changing the model will result in an exception.
I'm using EF 4 and MVC in C#,
When my application loads, I would like load create some entities to be added to my database, so where is the best place to add thsi functionality using EF? Global.asax on Start application?
What is a reasonable name convention for the class... BootStrap?
Thanks
If you have existing database you should not include the initialization into your application. The only way how to make this work in existing database is to execute some initialization in Application_Start. The initialization must check existence of every entity you want to insert and insert data only if the entity is not present. Because your database already exists, the initialization logic will have to run every time you restart the application. To avoid this you would also need some flag in the database to mark that initialization was already done (one of inserted entity can be considered as a "flag" but only if the application cannot remove this entity).
EF normally seeds data only when creating database or after database migration.
Edit: If you are creating test data on your test database you should be happy with database recreation each time your model changes (or with migrations) and custom database initializer to seed your data.
I need to configure the database created by Entity Framework Code First MigrateDatabaseToLatestVersion class.
Is it possible to influence the database files parameters like size or maxsize? What interests me in particular, is there a way to add database files?
I assume I need to find the moment where the Entity Framework generates the CREATE DATABASE statement and influence it a bit. As far as I understand, the SqlServerMigrationSqlGenerator class is too late because the database already exists at this point.
Edit: According to comment this doesn't work:
You can just add code based migration using Add-Migration command and modify its Up method to execute Sql("ALTER DATABASE ...") and do what ever you want with your database.
Database is created through DbProviderServices - that is a bridging component between EF and specific database server. ObjectContext exposes operations for creating database and generating database creation script. DbMigrator use database creation operation when you execute Update. It checks that if Database exists and if not it uses ObjectContext.CreateDatabase. So if you want to change the process of creating the database you need to implement your own implementation of the migrator to change the way how Update method generates the database (maybe you just need a decorator which will create a database prior to executing DbMigrator.Update operation).
I'm migrating my project from database-first to code-first.
Entity Framework does some nice work creating my new database (that should mimic the old one).
I'm using a combination of data annotations and the fluent API to describe my tables.
My database has a few indexes and I would like Entity Framework to create them as well. It seems the old way to do this is to define your own Initializer and use custom T-SQL.
But now that we have EF Migrations it should be easier to do so.
I can't seem to figure out how to combine CreateDatabaseIfNotExists<> with an automatic migration to create the indexes. I've tried to use the MigrateDatabaseToLatestVersion<,> but it doesn't seem to perform the migration after the Database has been created.
What is the proper way to create indexes and constraints on database creation now that we have Entity Framework 4.3?
Don't use CreateDatabaseIfNotExists if you want to use migrations. Use MigrateDatabaseToLatestVersion from the beginning - it will create your database as well. Put your index creation code (calls to CreateIndex) into Up method of your migration class.
If you already have existing database and you want to use migrations you must first create initial migration.