In my application I enable Code First Migrations with some migrations, Also I use SQL Server Compact for integration test.
When I run my tests, Entity Framework create an empty database and tries to run migration on that empty database and thrown The specified table does not exist.
Based on this report I think usage of Migration in Entity Framework 6 has changed.
I test all Database Initializer with Context.Database.Create(); but in all case tabale's never created.
I don't know that this is EntityFramework's bug or not, but when I made rename the namespace of Migration Configuration class from default (Projectname/Migrations) to any none default name, migration works well.
Context.Database.Create() will not execute migrations! It only creates empty db. To Update database from code to latest version you need to use DbMigrator.Update method:
var migrator = new DbMigrator(new MyMigrationsConfiguration());
migrator.Update();
Alternatively you might use MigrateDatabaseToLatestVersion
Database.SetInitializer(new MigrateDatabaseToLatestVersion<BlogContext, Configuration>());
It is described in details here: http://msdn.microsoft.com/en-us/data/jj591621.aspx#initializer
In case someone still struggles to fix the issue.
The code that follows works for me: add-migration MyFirstMigration
Meanwhile add-migration "MyFirstMigration" with the migration name ramped in quote doesn't work.
There may be previous migration files which the ide may be referring to mostly likely due to caching.
Drop backup and drop target database if it exists, and drop the migration folder.
Now add the migration and you will be good to go.
It does happens when adding model and running add-migration command.
Here is the simplest cause of this issue:
Add a newly added model property into IdentityDbContex class.
Here are the steps:
create model
add property into IdentityDbContex class
run add-migration
update-database
Related
I'm using ASP.NET Core v3.1. I have a migration folder as shown below. Now I've lost my database.
How can I apply all migrations to new database?
Running the command update-database doesn't work.
please make sure your database engine is available.
and next step make sure your context and your startup class and program class configured.
I am trying to add and update second migration in asp.net core with a different name from Initial Migration, but during update-database the error says There is already an object named 'Values' in the database. How can I can I update the new Entity and not update the Values object.
it seems there is a problem in migration process,
run add-migration command in "Package Manager Console"
Add-Migration Initial -IgnoreChanges
do some changes, and then update database from "Initial" file:
Update-Database -verbose
For more details refer this link
https://stackoverflow.com/a/43687656/495455
Thanks for help, I finally find a solution. I had to remove all migrations and it worked perfectly with different name for the second migration
So, I'm trying out EF Code First, so that I can have the code drive updates to the database. I'm working on a ClickOnce app using LocalDB, so figured this may be the best solution for me, since otherwise changes to the MDF file will cause it to be overwritten on the client when deployed, thus losing everything entered before.
However, I'm now having my fair share of all new problems around Code First Migrations. I've followed through a Code First Migrations on MSDN, and I've managed to get the initial Configuration created, as well as the initial database creation.
The problems begin when I try to make my first actual migration. I added one single field to one of my models, and tried to make an explicit migration to handle that schema change for the next time I publish. Well...
PM> Add-Migration AddIsPercentField
Unable to generate an explicit migration because the following explicit migrations are pending: [201601052011180_InitialCreate]. Apply the pending explicit migrations before attempting to generate a new explicit migration.
Ok... I'll run update and try again:
PM> Update-Database
Specify the '-Verbose' flag to view the SQL statements being applied to the target database.
Applying explicit migrations: [201601052011180_InitialCreate].
Applying explicit migration: 201601052011180_InitialCreate.
Unable to update database to match the current model because there are pending changes and automatic migration is disabled. Either write the pending model changes to a code-based migration or enable automatic migration. Set DbMigrationsConfiguration.AutomaticMigrationsEnabled to true to enable automatic migration.
You can use the Add-Migration command to write the pending model changes to a code-based migration.
PM> Add-Migration AddIsPercentField
Unable to generate an explicit migration because the following explicit migrations are pending: [201601052011180_InitialCreate]. Apply the pending explicit migrations before attempting to generate a new explicit migration.
That's familiar, as that's the error (blatant lie?) it just told me earlier. Well, maybe if I undo my changes and update again, it will move to a valid state:
PM> Update-Database
Specify the '-Verbose' flag to view the SQL statements being applied to the target database.
Applying explicit migrations: [201601052011180_InitialCreate].
Applying explicit migration: 201601052011180_InitialCreate.
Running Seed method.
Ok, no warning this time. Should be golden. Field added back, project rebuilt. Here we go:
PM> Add-Migration AddIsPercentField
Unable to generate an explicit migration because the following explicit migrations are pending: [201601052011180_InitialCreate]. Apply the pending explicit migrations before attempting to generate a new explicit migration.
So... is there actually a working way to generate explicit migrations for any changes beyond the first?
EDIT: I made some forward progress on this, I believe. I did notice that the __MigrationHistory table was not generated in my .mdf after running Update-Database, even though it said everything completed just fine. I believe the issue is actually around how the local database works within the application. The connection string references AttachDbFilename=|DataDirectory|. What I think is going on is that it is deploying the .mdf temporarily, updating that temporary deployment, thus ultimately not committing the changes.
I'm working on a solution I have in mind, which is to have migrations work against a copy of the blank .mdf put in a static location, so that the static .mdf will be used to track and determine changes, while the blank .mdf will be what goes out to clients with the deployment.
I found that the root of my problem was that the console commands were not actually able to make changes, thus track migrations, to my data file. This was due to the connection string to the data file referencing a deployed location, so the file being updated was merely temporary.
This was in part a good thing, because the whole point of using Code First Migrations in my project was to avoid a hash signature change to my .mdf (which should have simply remained blank, as a placeholder) when publishing, so that the data from previous versions would never be overridden and discarded. However, that also introduced the obvious (in retrospect) problem that EF could not track changes due to there never being a __MigrationHistory table.
The solution upon which I arrived was to have two .mdf files. The blank one, for deployments, and a second one, to which I would interact with Code First Migrations. So, I have the initial MyData.mdf of Build Action Content, and a second MyDataDesignTime.mdf of Build Action None. (The "Design Time" migration database shouldn't be deployed.)
Using this approach, I found that I could now work successfully with migrations, calling Update-Database and Add-Migration, making sure to pass the -ConnectionString parameter with AttachDbFilename pointed to the full path to my design time database.
Later, getting lazy to supply a long -ConnectionString parameter on every migration command, I added the design time path to my config connection strings, and updated my DbContext so that it uses the design time path initially, but which I would change at the beginning of run-time to use my actual target data file:
public partial class MyData : DbContext
{
public const string DesignTimeConnection = "MyDataConnectionStringDesignTime";
public static string ConnectionName { get; set; } = DesignTimeConnection;
public MyData()
: base("name=" + ConnectionName)
{
}
...
}
And at application initialization:
MyData.ConnectionName = "MyDataConnectionString";
This works, and it makes things simpler on me. However, the one minor issue I'm left with is that I have a full static path which applies only to my environment left in the app.config file. Not currently an issue, as I'm the only dev on this project, but it's a code smell that I'm not happy with. Is there some path variable that I can use, such that it still points to the actual design time data (not any temporary, deployed file), but does so relative to the active, open project?
I am following the offical asp.net "Getting started with EF 5 using MVC 4". In that tutorial, the database is created when the migrations are performed(in my understanding). When I was looking at the EF 5 with Mvc 5 tutorial they didn't use migrations to create a database. They use database initializer. So, I was wondering could create a database for your project without using migrations in EF 5? Also, what would the difference be with both these approaches?
Code first Migrations and using Package Manager Console Commands to do upgrades can get a bit confusing at first.
You can use the initializer to CreateDatabaseIfNotExists , DropCreateIfModelChanges, DropCreateDatabaseAlways and to MigrateDatabaseToLatestVersion
See the interface IDatabaseInitializer<TContext>.
CreateDatabaseIfNotExists // is the Default initializer.
So this is why it appears EF just does things for you sometimes.
So the answer is "YES you can "Create a Database without Migrations"
But the difference is not obvious and if you would do that long term is another question.
If you are using migrations. It would Update the Db to match the code first model.
If there is NO database, then that means creating the database.
So Thats why Automated migrations and CreateDB look confusing since they can result in same outcome sometimes. But technically they are different.
So generally it is sufficient to use code first automatic "migrations" only.
Migrations can be either Automatic or "managed".
The managed migrations approach invovles generating code , tweaking the code and running PM commandlet or POwershell command to actually perform the migration.
With Automated migrations you just need set the intitializer and Access the DBContext.
There are 2 parts to the process.
a) The DB Initializer step.
do this immediately before instantiating YourDBContext.
//eg
// DONT TOUCH MY DB or i break your back!
Database.SetInitializer(new ContextInitializerNone<YourDbContext>()); // Do Nothing,
// OR
// yes migrate my db to match my code please.
Database.SetInitializer(new MigrateDatabaseToLatestVersion<YourDbContext, YourMigrationConfiguration>()); // Set to migration is requested, see config class below
The Confirguration class specified when using Migration initializer looks like this
public class YourMigrationConfiguration<TContext> : DbMigrationsConfiguration<TContext>
where TContext : DbContext{
protected YourMigrationConfiguration() {
AutomaticMigrationsEnabled = true; // run it when needed. Do not wait for my PM Command
AutomaticMigrationDataLossAllowed = true; // if the new db look means dropping tables or columns go ahead and kill my data. So use this option with caution.
}
then just trigger the migration in code when required.
Context.Database.Initialize(true); // i place this inside a method on my UoW class
Code first Db initialization strategies.
Code first migrations recommended reading
Managed Migrations
There are many articles on the web on this topic.
I am using EF Code First with EF 5 in VS 2012. I use PM update-database command and I have a simple seed method to fill some tables with sample data.
I would like to delete and recreate my x.mdb. The update history seems to be out of sync. If I comment out all my DBSets in my context, update-database runs with no error but leaves some tables in the DB. As I have no valuable data in the DB it seems to the simplest to reset the all thing.
How can I accomplish this?
If I'm understanding it right...
If you want to start clean:
1) Manually delete your DB - wherever it is (I'm assuming you have your connection sorted), or empty it, but easier/safer is to delete it all together - as there is system __MigrationHistory table - you need that removed too.
2) Remove all migration files - which are under Migrations - and named like numbers etc. - remove them all,
3) Rebuild your project containing migrations (and the rest) - and make sure your project is set up (configuration) to build automatically (that sometimes may cause problems - but not likely for you),
4) Run Add-Migration Initial again - then Update-Database
If you worked the correct way to create your migrations by using the command Add-Migration "Name_Of_Migration" then you can do the following to get a clean start (reset, with loss of data, of course):
Update-database -TargetMigration:0
Normally your DB is empty now since the down methods were executed.
Update-database
This will recreate your DB to your current migration
For EntityFrameworkCore you can use the following:
Update-Database -Migration 0
This will remove all migrations from the database.
Then you can use:
Remove-Migration
To remove your migration.
Finally you can recreate your migration and apply it to the database.
Add-Migration Initialize
Update-Database
Tested on EFCore v2.1.0
Similarly for the dotnet ef CLI tool:
dotnet ef database update 0 [ --context dbcontextname ]
dotnet ef migrations add Initialize
dotnet ef database update
Single Liner to Drop, Create and Seed from Package Manager Console:
update-database -TargetMigration:0 | update-database -force
Kaboom.
How about ..
static void Main(string[] args)
{
Database.SetInitializer(new DropCreateDatabaseIfModelChanges<ExampleContext>());
// C
// o
// d
// i
// n
// g
}
I picked this up from Programming Entity Framework: Code First, Pg 28 First Edition.
dbctx.Database.EnsureDeleted();
dbctx.Database.EnsureCreated();
I am using .net Core 6 and this code is directly stripped out of the Program.cs
using Microsoft.EntityFrameworkCore;
namespace RandomProjectName
{
public class Program
{
public static async Task<int> Main(string[] args)
{
var connectionString = "Server=YourServerName;Database=YourDatabaseName;Integrated Security=True;";
var optionsBuilder = new DbContextOptionsBuilder<YourDataContext>();
optionsBuilder.UseSqlServer(connectionString);
var db = new YourDataContext(optionsBuilder.Options);
db.Database.EnsureDeleted();
db.Database.Migrate();
}
}
}
You should have at minimum initial migration for this to work.
There re many ways to drop a database or update existing database, simply you can switched to previous migrations.
dotnet ef database update previousMigraionName
But some databases have limitations like not allow to modify after create relationships, means you have not allow privileges to drop columns from ef core database providers but most of time in ef core drop database is allowed.so you can drop DB using drop command
and then you use previous migration again.
dotnet ef database drop
PMC command
PM> drop-database
OR you can do manually deleting database and do a migration.
If you created your database following this tutorial: https://msdn.microsoft.com/en-au/data/jj193542.aspx
... then this might work:
Delete all .mdf and .ldf files in your project directory
Go to View / SQL Server Object Explorer and delete the database from the (localdb)\v11.0 subnode. See also https://stackoverflow.com/a/15832184/2279059
Using EF6 with ASP.Net Core 5 I found these commands handy during first initialization of the database:
Remove-Migration -force; Add-Migration InitialMigration; Update-Database;
It removes the last migration (should be the only one), creates it again, then refreshes the database. You can thus type these three commands in one line into the Package Management Console after editing your DbContext and it'll update InitialMigration and database.
A little annoying is that it'll compile your project three times in a row but a least no further manual steps (like deleting the migration files) are necessary.
When you remove an entity you'll need to issue Remove-Database before updating. So the line becomes:
Remove-Migration -force; Add-Migration InitialMigration; Remove-Database; Update-Database;
Problematic here: You need to confirm removing the database + 4 rebuilds.
Take these steps:
Delete those object which should be deleted from the context // Dbset<Item> Items{get;set;}
and in Nuget Console run these commands
add-migration [contextName]
update-database -verbose
It will drop table(s) that not exist in Context, but already created in database
Let me help in updating the answers here since new users will find it useful.
I believe the aim is to delete the database itself and recreate it using EF Code First approach.
1.Open your project in Visual Studio using the ".sln" extention.
2.Select Server Explorer( it is oftentimes on the left)
3.Select SQL Server Object Explorer.
4.The database you want to delete would be listed under any of the localDB. Right-Click it and select delete.
Since this question is gonna be clicked some day by new EF Core users and I find the top answers somewhat unnecessarily destructive, I will show you a way to start "fresh". Beware, this deletes all of your data.
Delete all tables on your MS SQL server. Also delete the __EFMigrations table.
Type dotnet ef database update
EF Core will now recreate the database from zero up until your latest migration.