I'm using EF 5.0 (CodeFirst) with VS 2012. I changed my model (entity) and manually changed my database. I try to run the application and the following error appears:
The model backing the 'XXXContext' context has changed since the
database was created. Consider using Code First Migrations to update
the database (http://go.microsoft.com/fwlink/?LinkId=238269).
My only change was the name of the entity property (column in the database).
Its automate or ignore the synchronization? For the same has been done manually, only the application that does not recognize it. Or run something that validates manual synchronization.
Where is the recorded synchronization information for the application to know that there was a change?
Thanks
You have the option of using Database Initializers or Migrations. In your application startup you can enable initializers with the following:
System.Data.Entity.Database.SetInitializer<YourDbContextType>(new DropCreateDatabaseIfModelChanges());
You can also subclass and create your own logic if needed. See http://www.codeguru.com/csharp/article.php/c19999/Understanding-Database-Initializers-in-Entity-Framework-Code-First.htm for more info.
You can also enable migrations and let them automatically update your database. Running Enable-Migrations in the Package Manager Console does this. Look here for more information http://msdn.microsoft.com/en-us/data/jj591621.aspx
Related
I need to set up an automated way to manage table privileges and ownership during migration execution.
Currently, the workflow is that a developer runs database migrations using his personal account during the new version release. The issue here is that he is automatically set as the owner of newly created tables, and the owner and privileges for table access have to be changed manually afterwards. I'm looking for a way to automate this, but could not find a solution. My assumption is that this is not supported by ef core as permission/ownership handling differs on underlying database used, but I don't see a reason for specific ef providers not to have this functionality. I'm probably missing something obvious and any help would be appreciated.
We are using .NET 5 with EF Core 5.0 with Postgresql.
I don't understand the concept of automatic migration.
Having set AutomaticMigrationsEnabled = true; in the Migrations.Configuration class I can't find the place where migration steps are stored.
How will Entity Framework recognize the current state of a production database and update it accordingly when, e.g., my console application is run at the customers' office?
Any information on this is very appreciated.
To answer your first question: They aren't stored anywhere. Automatic migrations only means that the migration will take place without you having to do anything about it. Generating a migration file only occurs when you are doing a manual migration. The only trace that automatic migration leaves is a new record in the _MigrationHistory table of your database--which will only be a serialized version of the new model, and not what your changes were.
To answer your second question: You shouldn't have to. Once you're in production, your client shouldn't be able to adjust the database themselves. That's just a terrible idea.
I use Model-first with EF, and I want to have an automated gap DDL script when I change my model. With "Entity Framework Database Generation Power Pack" We had it in past, but I read that was not supported in VS2012.
Any changes about that?
For Who dont't understand this need, I would like to remmember that in production enviroments, development team dosen't have access to DB. We must create and send to production Support team, DDL deployment scripts that preserve data and all DB without any recreation.
You should have a look at Database.SetInitializer, which mainly determines what happens if there is no database present when the application is started for the first time, and migrations which can be used to update the datebase when a new application version (which requires an updated database) has been deployed. If the built-in support for migrations data aren't enough, you also have the ability to add raw SQL data to handle migrating to a new version.
Working on EF Codefirst 5.0, on deployment we created the empty database in order to create the username and permission level settings, because in the database server this user is specific to only this database.
so we done above steps and tried to run the application, it throws below exception as it was not created by the EF code first, any solutions for handling this scenario?
help on this really appreciated.
Error:
Model compatibility cannot be checked because the database does not contain model metadata. Model compatibility can only be checked for databases created using Code First or Code First Migrations.
How can I do incremental developments with entity framework code first database. Because if I change something i model classes it will regenerate the database which cased to loss my data already in the database. I'm using DropCreateDatabaseIfModelChanges . Is there any thing other than that to execute alter quires rather than recreating.
EF Code First Migrations would help you here, it's in alpha/CTP currently: Entity Framework Code First Migrations: Alpha, also check out the ADO.NET team blog:
The most consistent request we have heard from you since releasing EF
4.1 has been for a migrations solution for Code First that will
incrementally evolve the database schema as you model changes over
time. Today we are announcing the release of our first Community
Technical Preview (CTP) of our Code First Migrations work.
As I recall, the Microsoft docs tell you to be sure not to use DropCreateDatabaseIfModelChanges in production environments. The point of that option is to help you come up with code-based data population for your test runs. I haven't seen any tools to help with incremental changes when using code-first. Where I work, we use a database-first setup, and we create a change script for each new release that includes alter and insert statements.
incremental database development is not currently available in the current version of the codefirst framework however it is included in the roadmap for the next release which will ship with MVC 4
as of right now you would need to remove metadata tracking from the database conventions and update the database manually via scripting or using the sql tooling until this new convention is added to the framework