I have a team developing a web application using EF. They all have local copies of their DB, as well as there being a central DB for a published version of the app. Some of the devs, and the CI server, have built their initial DB from a later version of the model than others, and so when they run Update-Database or the migrate.exe tool, they get errors when running migrations they don't actually need.
Other than blowing away all DBs and starting over, what's the best way to get everyone on the same page migrations-wise? Can migrate or Update-Database be told to mark migrations as being applied even if they fail, and continue?
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I have 2 databases, development and production.
I added a new entity, added a migration then updated the development database.
It worked, development database has the new table.
I switched the database in my configuration to the production database.
I used Update-Database command from Package Manager Console but nothing happened.
My production database still doesn't have the new table.
What now?
What is the valid workflow for such scenario?
BTW, both databases already contain structure and data. The production database contains more recent data, the development database is one migration ahead.
UPDATE: I tried to revert the last migration on development database, it worked. Then I tried to apply it again on production. Didn't work. It seems like it refuses to apply the same migration again.
OK, I figured it out.
I assumed when I change the runtime profile for production the file appsettings.Production.json will be loaded on migration.
It didn't happen. The migration used appsettings.Development.json instead.
I changed the connection string in my appsettings.Development.json file to the production database and it worked.
It's weird, when I debug the web application it respects the settings. It either uses the development or production settings, as selected in Visual Studio. Migrations just use the development file.
If there's a cleaner way (IDK, tell the Update-Database command to use a different appsettings file), please let me know in comment.
So I have an EF Core project. When I need to add/migrations I issue and update command:
dotnet ef database update -v
This all works fine, if I need to update the QA, Staging, Prod database I update the connection string in my appsettings.json file and run the command.
What happens if I don't have access to production from my local machine? How do you go about updating the database to the latest migration?
If I remember working with Entity Framework (not .net core). It would try and update the database automatically when I deploy a new version of the .net application. Does this functionality still exist in .NET core?
Yes you could run
dbContext.Database.Migrate();
On startup but it is generally not a good idea to conflate database migration with your application lifecycle - best practice is to keep your application start up as fast and simple as possible because an application start failure is hard to diagnose remotely, and a migration would introduce a lot of unwelcome complexity.
The alternative is to run a migration operation as part of your deployment. It depends on what method you use to deploy but say for example you use a CI server, you will be able to run
dotnet ef database update
after copying the new code but before starting the application back up.
I'm faced with this scenario: I want to release my software into production on Azure, but there's a code-first database migration that must be applied at the same time to an Azure SQL database. During the time that new software version is pushed without the new database schema (or vice-versa), there will be a period of time that software will throw the exception The model backing the 'BlogContext' context has changed since the database was created..
My software is deployed upon pushing git commits to a branch using continuous integration in Visual Studio Team Services, so I really need a way to run update-database at the same time.
It appears this can be done using a manual publish from Visual Studio by checking the Update Database box (below), but I need this to be automated.
If you do not care about the data just drop the dbo.__MigrationHistory table
Hope this helps.
Can you take direct control over the deployment process (Team Services can help, or Octopus, Jenkins, others)? If so, deploy the database ahead of the code. That's how I would do it if I wasn't using Entity Framework. I would assume the same even with Entity Framework.
An entity framework context is initialised, by default, using CreateDatabaseIfNotExists<TContext>. If the database schema is different than the EF model, then error The model backing the 'BlogContext' context has changed since the database was created. will be triggered.
By adding to your db context contructor Database.SetInitializer<context>(null); the model error will not be triggered. This means you can deploy schema changes to production, without causing model errors, ahead of the new version of the application being deployed that contains the new db context, which equals no down-time.
Make use of an appSetting so that production code will use the null initializer.
I have been following a number of tutorials regarding code-first migrations and am now at the stage where I am ready to deploy to our staging server.
We normally publish web apps to the filesystem and then manually update sites through Remote Desktop (not the greatest I know).
All the tutorials and best practises as far as code first and deployment go seem to be either out of date of specific to Azure deployment.
What is the current best practise for deploying a web app that has been developed with code first migrations (EF6) to a live environment? How then are updates to the live environment handled?
I understand that I can generate scripts using Update-Database but then these do not include any Seed Data. Are scripts the way to go?
Thanks,
You can use DBMigrator update menhod - this will run any pending migrations. The Seed method in your Configuration class will run every time your application starts.
You can also use migrate.exe to run database updates.
I guess I should have thought of this before I started my project but I have successfully built and tested a mini application using the code-first approach and I am ready to deploy it to a production web server.
I have moved the folder to my staging server and everything works well. I am just curious if there is a suggested deployment strategy?
If I make a change to the application I don't want to lose all the data if the application is restarted.
Should I just generate the DB scripts from the code-first project and then move it to my server that way?
Any tips and guide links would be useful.
Thanks.
Actually database initializer is only for development. Deploying such code to production is the best way to get some troubles. Code-first currently doesn't have any approach for database evolution so you must manually build change scripts to your database after new version. The easiest approach is using Database tools in VS Studio 2010 Premium and Ultimate. If you will have a database with the old schema and a database with the new schema and VS will prepare change script for you.
Here are the steps I follow.
Comment out any Initialization strategy I'm using.
Generate the database scripts for schema + data for all the tables EXCEPT the EdmMetadata table and run them on the web server. (Of course, if it's a production server, BE CAREFUL about this step. In my case, during development, the data in production and development are identical.)
Commit my solution to subversion which then triggers TeamCity to build, test, and deploy to the web server (of course, you will have your own method for this step, but somehow deploy the website to the web server).
You're all done!
The Initializer and the EdmMetadata tables are needed for development only.