Our team works on a website with ASP MVC5 & EF5. there are 3 machines involved in my question:
Developer's machine
Test server
Production server
So a regular work cycle is: the developer adding features & puts them on the test server when there are some approved tested features they goes to the Production server.
When there are no model changes - everything works great.
But, when there are model changes - sometimes the migration gets wrong.
and the DB get so messed up so we need to backit up, clear everything & copy the data from the backup.
what we do is:
Add migration on dev-env.
Copy all the source to the test/production (Model & Migration folders).
Update database.
when doing this basic cycle some times the migration failes to update because of table already exists; I guess im doing something wrong in the process.
Another bad thing:
we have copy of the development environment on the Test & Production servers - my guess is that we dont need VS on the server in order to update version (we use the VS to run the EF commands from the package manager.
My question is
Is there any best practice/manual regarding dev->test->production process & how to do it right with code first & no visual studio on the servers?
How to re-create the database using EF6?
I have tried both of following post but, i don't know why its not working and getting same error.
How do I generate an EF6 database with migrations enabled, without using update-database?
Migrations is enabled for context ''but the database does not exist or contains no mapped tables
I have already published my sample on the web server. I am using Sql Server 2012 Express DBMS.
When i have created my application and published it on web server it was working fine. It has created database automatically. After that i have made some changes in ApplicationDBContext and added some properties in IdentityModes(ApplicationUser). Then I have migrated database on my Local IIS Express and it was working fine. Then I have tried to publish my sample again on web server but, this time it shows an error.
Migrations is enabled for context 'ApplicationDbContext' but the database does
not exist or contains no mapped tables. Use Migrations to create the database
and its tables, for example by running the 'Update-Database' command from the
Package Manager Console.
I have deleted the database on web server and tried again. but, still i am facing same error. Now, there is an empty database without table.
Application is creating database on User Registration.
I have also read this post and tried to call dbContext.Database.Initialize(true); and ((IObjectContextAdapter)myContext).ObjectContext.CreateDatabase() method but, still its not working.
First, automatic migrations are nice for development but it's a hugely bad idea to rely on them in production. Second, at some point you turned off automatic migrations, which is why your production database is no longer having tables created in it.
Go ahead and leave automatic migrations off; even in development it's better to know exactly what changes you're making to your database by generating a migration, seeing the code that will be executed, and only then running Update-Database to apply those changes.
You have a number of choices in terms of getting schema updates into production, but they all boil down to roughly the same procedure.
Generate a new migration against your local database.
If you want to update your production database via SQL, run Update-Database -Script. This will generate a SQL file with the code to run on the database to migrate the schema. Hand this off to your DBA if you have one or review the SQL code yourself and then apply it manually to your database via Management Studio.
Run Update-Database. This time without -Script to make the changes to your local database schema.
If you didn't generate the SQL file in step 2, view your local database in SQL Server Object Explorer in Visual Studio. Right-click on the local database there and choose, "Schema Compare...". Follow the wizard to compare with your production database. In the end, you can either generate a SQL file with the necessary changes that need to be made (which again, you'd hand off to your DBA if you have one), or you can migrate to production directly from Visual Studio. However, this is not really recommended. It's always best to generate the SQL, which you or your DBA can then inspect before applying the changes live.
Chris Pratt is correct BTW.
I had downloaded a project in which I needed to just run "Update-Database
Here are the quick screenshots
Then at the bottom of Visual Studio
PM> Update-Database
DONE
I have got into a bad state with my ASP.Net MVC 5 project, using Code-First Entity Framework. I don't care about losing data, I just want to be able to start fresh, recreate the database and start using Code-First migrations.
Currently I am in a state where every attempt to Update-Database results in an exception being thrown or getting an error message. Also the website can't access the database correctly. How can I wipe all migrations, re-create the database and start from scratch without having to create a new project? In other words, I want to keep my code but drop the database.
Later I will also want to get the deployment database (SQL Server on Azure) in sync. Again, I don't mind dropping all the data - I just want to get it working.
Please provide any how-to steps to get back to a clean state. Much appreciated.
Follow below steps:
1) First go to Server Explorer in Visual Studio, check if the ".mdf" Data Connections for this project are connected, if so, right click and delete.
2 )Go to Solution Explorer, click show All Files icon.
3) Go to App_Data, right click and delete all ".mdf" files for this project.
4) Delete Migrations folder by right click and delete.
5) Go to SQL Server Management Studio, make sure the DB for this project is not there, otherwise delete it.
6) Go to Package Manager Console in Visual Studio and type:
Enable-Migrations -Force
Add-Migration init
Update-Database
7) Run your application
Note: In step 6 part 3, if you get an error "Cannot attach the file...", it is possibly because you didn't delete the database files completely in SQL Server.
I would like to add that Lin's answer is correct.
If you improperly delete the MDF you will have to fix it. To fix the screwed up connections in the project to the MDF. Short answer; recreate and delete it properly.
Create a new MDF and name it the same as the old MDF, put it in the same folder location. You can create a new project and create a new mdf. The mdf does not have to match your old tables, because were going to delete it. So create or copy an old one to the correct folder.
Open it in server explorer [double click the mdf from solution explorer]
Delete it in server explorer
Delete it from solution explorer
run update-database -force [Use force if necessary]
Done, enjoy your new db
UPDATE 11/12/14 - I use this all the time when I make a breaking db change.
I found this is a great way to roll back your migrations to the original db:
Puts the db back to original
Run the normal migration to put it back to current
Update-Database -TargetMigration:0 -force [This will destroy all tables and all data.]
Update-Database -force [use force if necessary]
This worked for me:
Delete database from SQL Server Object Explorer in Visual Studio.
Right-click and select delete.
Delete mdf and ldf files from file system - if they are still there.
Rebuild Solution.
Start Application - database will be re-created.
While this question is premised by not caring about the data, sometimes maintenance of the data is essential.
If so, I wrote a list of steps on how to recover from Entity Framework nightmare when the database already has tables with the same name here: How to recover from Entity Framework nightmare - database already has tables with the same name
Apparently... a moderator saw fit to delete my post so I'll paste it here:
How to recover from Entity Framework nightmare - database already has tables with the same name
Description: If you're like us when your team is new to EF, you'll end up in a state where you either can't create a new local database or you can't apply updates to your production database. You want to get back to a clean EF environment and then stick to basics, but you can't. If you get it working for production, you can't create a local db, and if you get it working for local, your production server gets out of sync. And finally, you don't want to delete any production server data.
Symptom: Can't run Update-Database because it's trying to run the creation script and the database already has tables with the same name.
Error Message: System.Data.SqlClient.SqlException (0x80131904): There
is already an object named '' in the database.
Problem Background: EF understands where the current database is at compared to where the code is at based on a table in the database called dbo.__MigrationHistory. When it looks at the Migration Scripts, it tries to reconsile where it was last at with the scripts. If it can't, it just tries to apply them in order. This means, it goes back to the initial creation script and if you look at the very first part in the UP command, it'll be the CreeateTable for the table that the error was occurring on.
To understand this in more detail, I'd recommend watching both videos referenced here:
https://msdn.microsoft.com/en-us/library/dn481501(v=vs.113).aspx
Solution: What we need to do is to trick EF into thinking that the current database is up to date while not applying these CreateTable commands. At the same time, we still want those commands to exist so we can create new local databases.
Step 1: Production DB clean
First, make a backup of your production db. In SSMS, Right-Click on the database, Select "Tasks > Export Data-tier application..." and follow the prompts.
Open your production database and delete/drop the dbo.__MigrationHistory table.
Step 2: Local environment clean
Open your migrations folder and delete it. I'm assuming you can get this all back from git if necessary.
Step 3: Recreate Initial
In the Package Manager, run "Enable-Migrations" (EF will prompt you to use -ContextTypeName if you have multiple contexts).
Run "Add-Migration Initial -verbose". This will Create the initial script to create the database from scratch based on the current code.
If you had any seed operations in the previous Configuration.cs, then copy that across.
Step 4: Trick EF
At this point, if we ran Update-Database, we'd be getting the original error. So, we need to trick EF into thinking that it's up to date, without running these commands. So, go into the Up method in the Initial migration you just created and comment it all out.
Step 5: Update-Database
With no code to execute on the Up process, EF will create the dbo.__MigrationHistory table with the correct entry to say that it ran this script correctly. Go and check it out if you like.
Now, uncomment that code and save.
You can run Update-Database again if you want to check that EF thinks its up to date. It won't run the Up step with all of the CreateTable commands because it thinks it's already done this.
Step 6: Confirm EF is ACTUALLY up to date
If you had code that hadn't yet had migrations applied to it, this is what I did...
Run "Add-Migration MissingMigrations"
This will create practically an empty script. Because the code was there already, there was actually the correct commands to create these tables in the initial migration script, so I just cut the CreateTable and equivalent drop commands into the Up and Down methods.
Now, run Update-Database again and watch it execute your new migration script, creating the appropriate tables in the database.
Step 7: Re-confirm and commit.
Build, test, run. Ensure that everything is running then commit the changes.
Step 8: Let the rest of your team know how to proceed.
When the next person updates, EF won't know what hit it given that the scripts it had run before don't exist. But, assuming that local databases can be blown away and re-created, this is all good. They will need to drop their local database and add create it from EF again. If they had local changes and pending migrations, I'd recommend they create their DB again on master, switch to their feature branch and re-create those migration scripts from scratch.
Just want to add to the excellent answer of #Lin:
5) B.
If you don't have SQL Management Studio, go to "SQL Server Object Explorer".
If you cannot see your project db in the localdb "SQL Server Object Explorer", then click on "Add SQL server" button to add it to the list manually. Then you can delete the db from the list.
A possible very simple fix that worked for me. After deleting any database references and connections you find in server/serverobject explorer, right click the App_Data folder (didn't show any objects within the application for me) and select open. Once open put all the database/etc. files in a backup folder or if you have the guts just delete them. Run your application and it should recreate everything from scratch.
My solution is best suited for :
- deleted your mdf file
- want to re-create your db.
In order to recreate your database you need add the connection using Visual Studio.
Step 1 : Go to Server Explorer add new connection( or look for a add db icon).
Step 2 : Change Datasource to Microsoft SQL Server Database File.
Step 3 : add any database name you desire in the Database file name field.(preferably the same name you have in the web.config AttachDbFilename attribute)
Step 4 : click browse and navigate to where you will like it to be located.
Step 5 : in the package manager console run command update-database
I wrote a small WPF app using EF without enabling migrations a while ago and deployed. I have continued to work on my application and have realised that my current version is going to fail when I redeploy because I have not got upgrade scripts.
Does my idea below sound like it could work?
Create a new project and use EF, enabling migrations. Create new model project and DAL. Create model by pointing to existing deployed DB and set as initial migration. Enable migrations on my existing project and paste my migrations folder into existing project then add migration.
My thinking is that I will get initial DB matching existing deployed schema then when I add migration it will check against initial and create me the up/down for when I next deploy.
Any advice appreciated.
My deployment had had migrations enabled (I found out after taking backup, don't remember running that but must've because I have a _migrationHistory table!!!!), unfortunately, and amateurishly, I had deleted the migrations folder from my dev code and not checked into source control prior to doing so.... So I:
Backed up client database
Restored the backup from step 1 on my local SQLExpress
Pointed my application connection string at newly restored DB
Opened package manager console
Selected my DAL project as default project
Ran "enable-migrations"
This straight away picked up my previous, initial creation from database. This takes me back to before I messed around and deleted migrations folder from project!!!
Thank you MS boys & girls.
We're considering using EF 4.3.1 code-based migrations, but aren't clear about how to integrate Migrations with our present dev/deployment methodology...
The app in-question is a desktop WPF app, with each desktop having its own SQL Server instance (each with 4 separate databases). It is deployed into a "field" environment with zero local IT support. Any database migration must be done using SQL scripts executed by the installer (probably InstallShield). There will not be anyone available who can run a command at a PMC prompt to upgrade the db when it is deployed/upgraded at a field location. Thus the ultimate "output" from EF Migrations must be a set of SQL scripts, which the installer will selectively apply.
Also, we have multiple developers making concurrent database changes.. there is NO DBA. Each developer simply checks-in their code (model) changes to TFS, and the next time they do get-latest, the changes to the model automatically cause a new database to be created on their dev system. So how can we now have each developer perform their own local migrations (rather than deleting/recreating their local databases), and then manage/consolidate/combine those migrations? And what about collisions?
During dev and unit-testing, each developer may delete their (entire) local database multiple times during a single checkout/checkin iteration. This works great with Code First, since the database gets automatically rebuilt when the app is restarted. But this means that the _MigrationHistory table in the database also gets deleted. How do we handle this? Don't we need the migration history of each dev system? If not, then where/how do we detect the aggregate changes which need to be applied to the delivered system?
I can see the value of using Migrations to deal with the mechanics of migrating a database, but what's not clear is how to take advantage of it without introducing a centralized database "change-control" bottleneck into the dev cycle, and thus losing one of the key benefits of Code First.
Any insight/advice would be greatly appreciated!
DadCat
I know this is an old question but I thought I'd post some of my experiences with EF Migrations (v6.1).
Each dev will be fine. Migrations are put into classes with a timestamp in the name, so no collisions will happen. The DB on the dev's machine will be updated after doing a get latest and running the app (or the update-database command).
Deleting the local db and recreating is fine. Just make sure the dev runs update-database before adding additional migrations or things will get out of sync. I'm a bit confused as to why they'd need to delete the local DB, but that's out of scope. You may find that your process needs to change to accommodate EF Migrations.
I can't help you with the installer question, as a similar question brought me here. The update-database command does have a -script option that will generate the proper change script, but I'm unclear how to automate that on a build server.