Recently I run add-migration command, and I have some mistakes, so I run remove-migration to undo it. But when I run add-migration again, it said: The name 'blablabla' is used by an existing migration. How to fix this. I already double check Migration folder, there is no migration that have that name.
Delete bin and obj folder in the src of your project, rebuild and It should allow you to add migrations with the same name. This works for me.
It seems that they are cached in the bin and obj folder and when you try to add a new migration with the same name it checks those folders and throws you the error message.
Tested on .net core 2.2
Try to build your application after removing migration:
dotnet ef migrations add YourMigration
dotnet ef migrations remove
dotnet build
dotnet ef migrations add YourMigration
If you have access to your database, Go to the Database and Remove that Last Migration you add in the migration table. Then it should work again without any problem.
Check the "Data" folder. There are migrations there also. Delete the folder, re-run the build and should work.
Build -> Clean Solution does the job.
Check the \Migrations folder, delete the 'blala' name, both .cs. and Designer.cs. Run the add-migration again , should work.
maybe its exclude from the project. check TFS or file explorer.
Related
I deleted all migrations in the migrations folder and also deleted the database in SQL Server.
I know - now - these shouldn't be done, but I need to re-create the database structure to keep the application.
I tried 'add-migration initial' but the it simply generates an empty migration file and an snapshot file. If I try the 'remove-migration' then it complains about some missing migration file.
Is there anyway to 'reset' the snapshot like I just had created the DBContext, so it will create all the tables as in the current DbSet definitions?
I think the following solutions can help you:
First of all, make sure that the database is completely deleted because you said that the database was deleted in SQL. (After you create the first migration, a table called __EFMigrationsHistory is created, where the migration records are stored, if the database is not completely deleted, you must delete this table).
Second, delete the Migrations folder completely.
In the third step, run the following command.
Enable-Migrations -EnableAutomaticMigrations -Force
In the last step, run the following command
Add-Migration Initial
Steps :
Delete the state: Delete the migrations folder in your project
Delete the __MigrationHistory table in your database (may be under
system tables)
Run the following command in the Package Manager Console:
Enable-Migrations -EnableAutomaticMigrations -Force
Use with or without -EnableAutomaticMigrations
And finally, you can run:
Add-Migration Initial
Also this two link can help you :
Reset Entity-Framework Migrations
https://weblog.west-wind.com/posts/2016/jan/13/resetting-entity-framework-migrations-to-a-clean-slate
It seems the problem was in my project!
As #CodingMytra pointed in the comments, there were an active reference to the old database in my project. For some reason it was not rebuilding and not updating, thus not reflecting the changes in the models/dbcontext.
I created a new, empty project, imported all source files, generated a 'Initial' migration and updated the dabase successfully.
Thanks for all replys!
I am trying to update my database after a migration but I am getting an error saying
"There is already an object named [TableName] in the database."
below is how my project is structured
AtlasBooking.Client houses the startup.cs file and is contained in a different namespace while AtlasBooking.Storing is where I house pretty much everything else about database interaction
1.AtlasBooking.Client
-View folder
-ViewModels folder
-Controller folder
-Program.cs file
-Startup.cs file
-AtlasBooking.Client.csproj file
2. AtlasBooking.Storing
-DbContext folder
-Repositories folder
-Migrations folder
-AtlasBooking.Storing.csproj file
AtlasBooking.Client.csproj references AtlasBooking.Storing.csproj as shown below
<ItemGroup>
<ProjectReference Include="..\AtlasBooking.Storing\AtlasBooking.Storing.csproj" />
</ItemGroup>
I was successfully added the migration with the following
AtlasBooking.Storing: dotnet ef --startup-project ../AtlasBooking.Client/AtlasBooking.Client.csproj migrations add initialCreate --context AtlasBookingDbContext -o Migrations
to update database I used this
AtlasBooking.Storing: dotnet ef --startup-project ../AtlasBooking.Client/AtlasBooking.Client.csproj database update
I've also tried
AtlasBooking.Storing: dotnet ef --startup-project ../AtlasBooking.Client/AtlasBooking.Client.csproj database update --force
and I get the error Unrecognized option '--force'
how do I fix this?
you should use a double dash --force or -f for short hand.
https://learn.microsoft.com/en-us/ef/core/miscellaneous/cli/dotnet#dotnet-ef-database-update
Update
Nevermind, you can't force a database update. Your database must be out of sync with your migrations. If you don't have production data in the database, the easiest option would be to delete it and reapply your migrations.
I am working on an ASP.NET MVC project with Entity Framework with code first from database. I get the models for each table in the database. I made some changes in the models, enabled migrations and when I initial the migration I get an error:
There is already an object named 'TableName' in the database."
I tried with update-database -force but didn't help. The initial migration creates the tables that already exist!
How to make the initial migration apply the changes on the models and not create the tables from beginning?
And what is the best practice to sync changes between database and models in this case?
try to Run the
Add-Migration InitialCreate –IgnoreChanges
command in Package Manager Console. This creates an empty migration with the current model as a snapshot. and then Run the
Update-Database
command in Package Manager Console. This will apply the InitialCreate migration to the database. Since the actual migration doesn’t contain any changes, it will simply add a row to the __MigrationsHistory table indicating that this migration has already been applied.
see this
then change your models and add migration.
another approach is to simply comment all the code on up and down methods
Best and working For me idea is to comment all the code in UP and Down functions of Initial migration file and then fire
dotnet ef database update this should work fine,make sure you update migration before commenting out initial migration
If none of those answers work for you, you may check if in your code you use the method
context.Database.EnsureCreated()
Be aware that that method doesn't apply any migrations
(source) (you can check this making a sql query to the database and like "select * from __EfMigrationHistory" and be sure that there are no migrations on that database.
EF provide a really good method to help this that is
context.Database.Migrate()
that no only it will ensure that you have a database, but also use migrations and migrate yout db to the last version.
Hope it helps
This error appears when you deleted previous migrations and your new migration try to create new table that already exist. Recover previous migration and everything will be ok.
Amr Alaa solution works, but the database didn't migrate to the latest model.
Here's how it worked (using automatic migration) :
Delete Migrations folder
Execute enable-migrations
Set this two properties to true in the newly created Configuration.cs
public Configuration()
{
AutomaticMigrationsEnabled = true;
AutomaticMigrationDataLossAllowed = true;
}
Execute Update-Database -Force
Your database will be updated to latest scheme and ready.
hope this helps.
So I copy project solution form my friend and all migration where lost so if I change like username length to 129 and say to console Add-Migration it gives me empty migration?
So no UP and DOWN
So how do i need to do , to tell NuGet for past migration do i need to run migration all over or do i need to do something else ? I have (migrations folder )?? all help is welcome*
I did export and import data base in MySql
The following will update the database to the latest migration
Update-Database
If that does not work, you can apply the migrations individually
Update-Database -TargetMigration Initial
You can specify which migration to run like this:
update-database -TargetMigration:201405131513421_Inital
And then you can update to latest version like this:
update-database
In my main project, I have configured a connection string to my database like this:
<add name="DefaultStoreConnection" "provider....">
In my infrastructure project, I have a database context with a default constructor that passes the connection name to the base class:
public DatabaseContext() : base("DefaultStoreConnection") {}
As soon as my application starts, EF generates a 'store.sdf' (SQLCe database) in the application output folder (\bin).
Now, I wanted to reset all migrations and start with a plain database. I deleted the 'store.sdf' in the \bin directory, deleted all migration files and then called in the Package Manager Console:
Enable-Migrations -Force -ProjectName "MyInfrastructureProject" -StartUpProjectName "MyMainProject".
This worked fine, a new migrations configuration class was generated. Then I ran:
Add-Migration Initial -ProjectName....
And then the following line appears:
A previous migration called 'Initial' was already applied to the target database
Where? Where does this migration has been applied to? Where can I reset this 'migration'?
It should be in a folder containing all the migrations, but it's possible that it's deleted after it has been applied to database. You can see list of applied migrations in __MigrationHistory table of your target database. If you wish to rescaffold the database, empty the __MigrationHistory table.
I run to the same problem as you. After a day of google search without a single useful help, i figured it out myself that this is Visual Studio bug where your solution have more than one Mvc projects. The add-migration will check on the older Mvc project to create migration file for your current project (that is why i call it BUG).
To avoid this, you should only use one Mvc project per solution.
Have a look at the app_data folder of your project.