I successfully created an Entity Framework Core migration and updated the database with it.
Then after I added another class, I created a second migration called "update1" which created a class of the same name from the command line tools.
However, when I attempt to update the database, it fails.
Here is the commands I used
dotnet ef migrations add update1 -c MyDbContext
dotnet ef database update update1 -c MyDbContext
and it failed with
There is already an object named MyTable in the database
which is a table which was created in the initial migration.
How can I tell it to either ignore the error, or else to only attempt to run the update1 migration?
Edit: deleting the table that was already there caused this odd behavior to stop happening and now it works as expected.
Thanks
You have to remove the unwanted migration from the __MigrationHistory table.After that you can run your latest migration.This is happened due to you have manually deleted the table.B'cos EF doesn't know anything about your manual operations hence __MigrationHistory table still exist your old migration details (i.e. manually deleted table's record).
In my case I used Ubuntu, EF 6 and the database was in the docker and it's doesn't updated DB.
I added --connection attribute and it's works, an example:
sudo dotnet ef database update --connection
"Server=localhost;Database=temp;User Id=sa;Password=xxxxxxx;"
Related
We wish to get rid of 100s of migration classes as DB schema in production is final.
Here are the steps I followed:
Delete Migrations folder.
Add-Migration -??
What command line switches, could help us?
EDIT:
If all goes well Up() method of migration should be empty right? For
example following is wrong generation on Add-Migration. Because if we
execute the project we will get duplicate table errors.
public partial class Sanity : DbMigration
{
public override void Up()
{
CreateTable(
"dbo.AccountPreferences",
c => new
{
AccountID = c.Guid(nullable: false),
}
.... for 1000s of tables
}
}
A clean migration would be something: when trying Add-Migration on subsequent changes, should not be getting any error.
Unable to generate an explicit migration because the following
explicit migrations are pending: [201712281054591_Sanity]. Apply the
pending explicit migrations before attempting to generate a new
explicit migration.
As you can see if we happen to execute Update-Database will get table already exist error.
Are we forced to always retains all migration copies?
See if this can help:
MVC3 and Code First Migrations - "model backing the 'blah' context has changed since the database was created"
Entity framework code first - how to run Update-Database for production database
How to delete and recreate from scratch an existing EF Code First database
note:
I'm writing this from memory, if you have issues let me know and I'll recheck exactly.
Also, my knowledge on this is from slightly older versions of EF as I haven't done much work there recently, but I doubt much has changed.
From what I can tell, if you want to...
a) keep the db,
b) clean your project migrations,
c) have the 2 'match', be in sync:
do the following:
- Remove the migration folder (your project)
- Run Add-Migration Initial - then should add one migration
- caution: it is safe but do backup, change connection string etc. before the next step
- Run Update-Database -Script - that doesn't update the db but creates the SQL script, including the migration table
- find the INSERT INTO [__MigrationHistory] records, just run those (on your db), insert them into the database
...then test with Add-Migration again, to see if it is going to make anything, should yield no new migrations, empty one.
Please read through the first link above and adjust approach as needed.
I'm sure there might be easier, shorter ways to do this (via PM console) but unaware of it at the moment.
Open your database.
Clear table __MigrationHistory
Remove migrations in the folder
Run Add-Migration MigrationName
Almost the same as accepted one, but no scripting the initial migration.
Drop the __MigrationHistory db table
Remove all the migration files in the Migrations folder
Run Add-migration Initial in Package Manager Console
Comment out the code inside of the Up method in the Initial Migration
Run Update-database in PM Console (just to create a Migration Entry)
Remove comments in the Initial migration
Wonder how long it will be "final" ?
Use:
Add-Migration Initial
After removing the migrations folders
I want to use EF code first migrations to create my models in the database. However, the database I will use already exists and is shared by other applications. My question is:
Do migrations erase the database? That would be a disaster!
Do migrations erase anything at all?
Q : Do migrations erase the database ?
A : No.You can do that without erasing it.
You have to do it as shown below on the Package Manger console.
Step 1 :
PM > Add-Migration InitialCreate –IgnoreChanges
Above command will create an empty migration with the current model as a snapshot.
Step 2 :
PM > Update-Database
Above command will apply the InitialCreate migration to the database. Hence the actual migration doesn’t contain any changes, it will add a row to the __MigrationsHistory table indicating that this migration has already been applied.
You can read more about it here : CF Migrations with an existing database
What I usually do in this situation is create a migration to the existing database and then remove everything out of the Up and Down methods and run the update. This way your code first migrations will be up to date with whats currently in the database so any new schema changes that are made will be the only thing picked up by adding a second migration.
I have enabled migrations. I am not using automatic migrations and I do not want to use them.
I have done 3 migrations.
In my development environment I am updating database via VS using the command
Update-Database -verbose -StartUpProjectName EntityFrameworkContext -TargetMigration <MigrationName>
In my devlopment environment, everything works correctly.
Now, I must update the database in production environment. I am using following command
Update-Database -verbose -StartUpProjectName EntityFrameworkContext -TargetMigration <MigrationName> -script
I run the generated script on production database. No error. The table __MigrationHistory looks to be good (I have just some doubt about the column Model that is different from dev environment). In this tabel I have the correct number of rows and the column MigrationId is correctly filled.
The database is exactly the same of the dev database. I have checked it.
I have updated also the program.
But, I do not understand why I still have always the same error:
The model backing the 'PublicAreaContext' context has changed since the database was created. Consider using Code First Migrations to update the database (http://go.microsoft.com/fwlink/?LinkId=238269).
I am going crazy.
Thank you for your help
I am working on a web project using ASP.Net 5 and EF7.
I have imported all the tables from existing database onto my models in my project. However, I am having problems in regards with migrations.
I have created the initial migration, made some changes on particular entity, create another migration following the changes I have made and now want to apply the changes on the database.
After running this command below:
dnx ef database update [Migration]
the dnx is trying to apply the 'initial' migration with all the entities which are already in database and this causes an error as below:
{ There is already an object named ['EntityName'] in the database. }
Can you please advise on how to do the migration on the existing database?
Thanks
Saeed
In EF6 you would run a migration with the -IgnoreChanges flag and it would take a snapshot of the model without any Up() code. This is missing from EF 7(EF Core) as indicated here.
The workaround for now is delete or comment out the code for existing database objects from the Up() code of the migration and then update-database. Subsequent migrations will then include only the changes.
After 2 days I found a way for EFCore that is not in google and internet!
How My steps works?
When you have a database with 10 table and you have data in tabales that you don't want to clear's data.and after this you will create new models in your code first and runnig to existing database and you will get error "Invalid object name 'tableName'." for query to new tables and you want to create migrations and do update it to existing database but first migration will create all queries for old and new tables if you run update-database you will get "There is already an object named ['EntityName'] in the database." for your initial migration.
How fix it?
Delete all migrations and snapshot in you database project
Delete __EFMigrationsHistory table in your existing database (if exist)
Run in Package manager console:
Note before run: This code will create new context and models of your existing database to Data folder so don't forgot to check you have not Data folder in your project.
Scaffold-DbContext "your connection string"
Microsoft.EntityFrameworkCore.SqlServer -OutputDir Data
Run in Package manager console:
Note before run: Create first migration for initial database with Data folder context (OldDataBaseContext is inside of your Data folder that created by step 2)
Add-Migration initial -Context OldDataBaseContext
Delete all code in Up method inside of created initial migaration in step 3
Run in Package manager console:
Note before run: Update databse with Data folder context (OldDataBaseContext is inside of your Data folder that created by step 2)
Update-Database -Context OldDataBaseContext
Delete data folder that created in Step 2
Go to snapshot and initial migration classes and change the deleted context from Data folder to main context that is exist in your database project (just fix it for build)
Run:
Note before run: Add migration for main context that have new database changes
Add-Migration newUpdate
Run:
Update-Database
I Hope this help someone.
If you are strongly believe, that new (EF7) database schema will match your old database schema (including index and key names) - you may run 'Initial' migration to empty (temporary) database and then copy __EFMigrationHistory table from there to your real database.
Otherwise, I recommend you create empty database using migration and use sql insert into ... select commands to copy data from your old database. Without this, you will receive exceptions when upgrading database later - for example changing index will lead to DropIndex and CreateIndex migration commands, and DropIndex will fail because there is no index with this name (index exist with other, pre-EF7 name).
In my projects - old (from EF6) and new database schemes are different, and I used second option.
Using Entity Framework 6, with a SQL Server database and code first migrations, I have migrations set up and running "happily", however I'm finding that every time I go to add another migration I get the following error first off:
Unable to generate an explicit migration because the following explicit migrations are pending: [201602090629398_Initial, 201602090638322_FixSitePageColumns, 201602110313468_RemoveRequiredTemplateId]. Apply the pending explicit migrations before attempting to generate a new explicit migration."
If I run update-database -force it complains (naturally) that the script fails because of already having been applied. A strange combination of doign this again and then the add-migration works and I can carry on updating to the latest migration.
The list of "pending" migrations also grows with every addded migration over time.
What could cause this "pending" state, when the migration HAS already been applied? I can confirm that the database has already been updated, the migration exists in __MigrationHistory, and the program is running along happily.
EDIT
I've also just run get-migrations and the following is being returned:
PM> get-migrations
Retrieving migrations that have been applied to the target database.
201602110313468_RemoveRequiredTemplateId
201602110311536_RemoveRequiredTemplateId
201602090638322_FixSitePageColumns
201602090629398_Initial
The weird thing here (possibly a red herring) is that 201602110311536_RemoveRequiredTemplateId is not a migration in my project, I think it may have been one that I created and then deleted, I didn't ever implicitly apply it to the database but it's in the __MigrationHistory table.
This happened to me because when running Add-Migration it couldn't connect to the database to see what migrations had been applied. I don't have my password stored in the connection string. The fix was to run Add-Migration specifying a complete -ConnectionString and -SqlProvider
Add-Migration MigrationName -verbose -ConnectionString "data source=foo.database.windows.net;initial catalog=FOO_DB;user id=admin;password=`"REDACTED`";MultipleActiveResultSets=True;App=EntityFramework" -ConnectionProviderName "System.Data.SqlClient"
Remove the entry for removerequiredtemplateid from the migrations database table and rerun your migration procedure.
Optionally, delete the table altogether, delete all of your migrations, rerun enable-migrations, create a new initial migration and run update-database again (basically, create a fresh start).
Remember to make the required backups beforehand.