Is there some way to add a post migration method to Code First EF migration?
All the stored proc's are in the Visual Studio project. Right now there is an approach to load the stored proc resource from the file and put it into it's own migration:
protected override void Up(MigrationBuilder migrationBuilder)
{
var script = ScriptMgr.LoadStoredProc( "StoredProcThatChanged.sql" );
migrationBuilder.Sql( script );
}
There is a weak link in this process: Each time the script changes (StoredProcThatChanged.sql) a new migration needs to be created to make sure it executes again. The problem is the previous migration is also loading the same file. When generating a new script, the process reads in the one file both times, effectively changing the previous migration. Which is a classic no-no.
This would be resolved if there is a post migration method where ALL stored proc's can be reapplied to the DB. Is such a step possible? If so, now is it done?
I have been digging into the efcore source code and it looks like it is possible, not ideal, but there might be a way...
It looks like efcore has an interface called IMigrator. It contains the method string GenerateScript(...). The implementation of it, class Migrator, has comments all over the place saying that it's implementation of GenerateScript is internal and subject to change. But... It looks to me like I can achieve my end goal:
class MyMigrator : Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator
{
public string GenerateScript(
string? fromMigration = null,
string? toMigration = null,
MigrationsSqlGenerationOptions options = MigrationsSqlGenerationOptions.Default)
{
var result = base.GenerateScript( fromMigration, toMigration, options);
results += MyPostSteps(...);
return results;
}
}
Will this work and does anyone know how I might go about replacing the default Migrator with the MyMigrator?
Related
I have a weird problem with Entity Framework code first migrations. I've been using EF and code first migrations on a project for months now and things are working fine. I recently created a new migration and when running Update-Database a restored backup of my database I get this error:
The model backing the context has changed since the database was
created. Consider using Code First Migrations to update the database
The migration does something like the following:
public override void Up()
{
using (SomeDbContext ctx = new SomeDbContext())
{
//loop through table and update rows
foreach (SomeTable table in ctx.SomeTables)
table.SomeField = DoSomeCalculation(table.SomeField);
ctx.SaveChanges();
}
}
I'm not using the Sql() function because DoSomeCalculation must be done in C# code.
Usually when I get something like this is means that I have updated my model somehow and forgot to create a migration. However that's not the case this time. The weird thing is that the error isn't even occurring on a migration that I created a few days ago and had been working fine.
I looked a quite a few articles about this and they all seems to say call
Database.SetInitializer<MyContext>(null);
Doing that does seem to work, but my understanding (based on this article) is that doing that will remove EF's ability to determine when the database and model are out of sync. I don't want to do that. I just want to know why it thinks they are out of sync all of a sudden.
I also tried running Add-Migration just to see if what it thought changed about the model but it won't let me do that stating that I have pending migrations to run. Nice catch 22, Microsoft.
Any guesses as to what's going on here?
I'm wondering if maybe the fact that migration listed above is using EntityFramework is the problem. Seems like maybe since it's not the latest migration anymore, when EF gets to it tries to create a SomeDbContext object it checks the database (which is not fully up to date yet since we're in the middle of running migrations) against my current code model and then throws the "context has changed" error.
It's possibly related to your using EF within the migration. I'm not sure how you're actually managing this, unless you've set a null database initialiser.
If you need to update data within a migration, use the Sql function, e.g.
Sql("UPDATE SomeTable SET SomeField = 'Blah'");
You should note that the Up() method is not actually running at the time of doing the migration, it's simply used to set up the migration which is then run later. So although you may think you've done something in the migration above the bit where you're using EF, in reality that won't have actually run yet.
If you cannot refactor your calculation code so it can be written in SQL, then you would need to use some mechanism other than migrations to run this change. One possibility would be to use the Seed method in your configuration, but you would need to be aware that this does not keep track of whether the change has been run or not. For example...
internal sealed class Configuration : DbMigrationsConfiguration<MyContext>
{
public Configuration()
{
AutomaticMigrationsEnabled = false;
}
protected override void Seed(MyContext context)
{
// Code here runs any time ANY migration is performed...
}
}
I tried replacing the EntityFramework code with regular ADO.NET code and it seems to work. Here is what it looks like:
public override void Up()
{
Dictionary<long, string> idToNewVal = new Dictionary<long, string>();
using (SqlConnection conn = new SqlConnection("..."))
{
conn.Open();
using (SqlCommand cmd = new SqlCommand("SELECT SomeID, SomeField FROM SomeTable", conn))
{
SqlDataReader reader = cmd.ExecuteReader();
//loop through all fields, calculating the new value and storing it with the row ID
while (reader.Read())
{
long id = Convert.ToInt64(reader["SomeID"]);
string initialValue = Convert.ToString(reader["SomeField"]);
idToNewVal[id] = DoSomeCalculation(initialValue);
}
}
}
//update each row with the new value
foreach (long id in idToNewVal.Keys)
{
string newVal = idToNewVal[id];
Sql(string.Format("UPDATE SomeTable SET SomeField = '{0}' WHERE SomeID = {1}", newVal, id));
}
}
I am trying to use Code First with Migrations. Even though there are no current changes to my model, I'm getting an exception. When I add a migration, the up and down are empty, but I get a runtime error with the message as follows:
An exception of type 'System.InvalidOperationException' occurred in
EntityFramework.dll but was not handled in user code
Additional information: The model backing the 'MyDataContext' context
has changed since the database was created. Consider using Code First
Migrations to update the database (http://go.microsoft.com/fwlink/?
My architecture is as follows:
DataAccess project that includes the context, fluid configurations and migrations code
Model project that contains the poco classes
Web API and MVC projects that each contain the connections string in their respective web.config files.
Additionally I have the following code:
DbInitializer
public static MyDataContext Create()
{
Database.SetInitializer(new MigrateDatabaseToLatestVersion<MyDataAccess.MyDataContext, MyDataAccess.Migrations.Configuration>());
return new MyDataContext(ConfigurationManager.ConnectionStrings["MyDataContext"].ConnectionString, null);
}
I started with AutomaticMigrationsEnabled = false; in the migration Configuration constructor, as it was my understanding that this would allow (and require) me to have more control over when migrations were applied. I have also tried setting this to true but with the same result.
I added a new migration upon receiving this error, and the Up method was empty. I updated the database to this new migration, and a record was created in the _migrationHistory table, but I still receive the error when I attempt to run the application. Also, the seed data was not added to the database.
protected override void Seed(MyDataAccess.MyDataContext context)
{
IdentityResult ir;
var appDbContext = new ApplicationDbContext();
var roleManager = new RoleManager<IdentityRole>(new RoleStore<IdentityRole>(appDbContext));
ir = roleManager.Create(new IdentityRole("Admin"));
ir = roleManager.Create(new IdentityRole("Active"));
ir = roleManager.Create(new IdentityRole("InActive"));
var userNamager = new UserManager<User>(new UserStore<User>(appDbContext));
// assign default admin
var admin = new User { UserName = "administrator", Email = "myAdmin#gmail.com" };
ir = userNamager.Create(admin, "myp#55word");
ir = userNamager.AddToRole(admin.Id, "Admin");
}
where
public class ApplicationDbContext : IdentityDbContext<User>
{
public ApplicationDbContext()
: base("MyDataContext", throwIfV1Schema: false)
{
}
...
The question: If Add-Migration isn't seeing any change in the model, why do I get this error when I run? Why isn't the seed code being hit? How do I fix this, or if that can't be determined, how do I further determine the root cause?
I am not sure if you found the answer to your problem, but this other answer I found here actually did it for me:
Entity Framework model change error
I actually ended up deleting the __MigrationHistory table in SQL Server which I didn't know it was being created automatically.
The article also talks about the option to not generate it I think by using this instruction: Database.SetInitializer<MyDbContext>(null); but I have not used it, so I am not sure if it works like that
This worked for me.
Go to Package Manager Console and Run - Update-Database -force
I bet your data context is not hooking up the connection string.
Check if it's not initialized with a localdb (something like (localdb)\v11.0) and not working with that when you might think it's set to something else.
My issue ended up being a conflict between Automatic Migrations being enabled and the initializer MigrateDatabaseToLatestVersion as described here.
I recently upgraded from EF6 alpha 1-3 to EF6 beta 1. This meant that I had to recreate all the migrations created using the alpha version.
So I tried to roll back to a migration created using EF5. But I hit the error Introducing FOREIGN KEY constraint on table may cause cycles or multiple cascade paths. I figure this is because I had neglected to fix Down migrations when I was fixing Up migrations for exactly the same problem. (Should have read this before)
Anyway, rather than try to fix it all up I am trying to reset all the migrations - as described here. I deleted my migrations table in the database and all migration .cs files, then in package manager Enable-Migrations -EnableAutomaticMigrations -Force and Add-Migration Initial
When I tried to run my application with my existing database initialiser (which has automatic migrations false) it failed because it tried to create tables that were already there. So I changed my initialiser to Database.SetInitializer(new DropCreateDatabaseAlways<MyContext>())
This time I got the Introducing FOREIGN KEY constraint on table may cause cycles or multiple cascade paths problem again during initialisation
So I changed ALL the cascadeDelete: true to cascadeDelete: false in the migration file
But I still get the same error!
Update 1 I removed all but the creation of 1 table in the migration file but I got the same error. There must be some kind of cache somewhere or it's picking up a file I don't know about or it's generating its own migration in the background
Update 2 I figured that when using DropCreateDatabaseAlways that EF must always generate the migrations and also that changing cascadeDelete to false in the migration file is the wrong place to do it. It should be done in the FluentAPI. So I added this line modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>(); to onmodelcreating. And I also deleted the Initial migration file. Then I ran the application and it correctly generated a database. I thought I'd cracked it but....
I changed initialisation to use my original configuration file:
internal sealed class Configuration : DbMigrationsConfiguration<SID2013Context>
{
public Configuration()
{
AutomaticMigrationsEnabled = false;
AutomaticMigrationDataLossAllowed = true;
}
protected override void Seed(etc..
}
Then I ran the application and it reported that the model had changed. So I did Add-Migration Update-Database and a migration file to create the database was created.
The problem now is that when I run the application it tries to run another update (even though AutomaticMigrationsEnabled = false). I get the "There is already an object named 'xxx' in the database" problem again. There is an entry in the migrations table that does not match the name of the configuration file.
If you would like to start work "code first migration" using an existing database, you can do the following:
I run the add-migration "InitialMigrations".
It explores the existing database and make it a migration step.
temporarily delete the contents of the "InitialMigrations" step:
public partial class InitialMigrations : DbMigration {
public override void Up()
{
//...
//...
}
public override void Down()
{
//...
//...
}
}
I run the update-database
This creates the appropriate entries in the table __MigrationHistory.
Restores the contents of the "InitialMigration" Go to work properly on an empty database.
That's it.
update: initializer
As I understand it, the 'DropCreateDatabaseAlways' always delete and create the database. This can only be used for the very first installation. If you have a working installation launchpad, you erase all data. That is why I hazardous.
I based on this article: coding.abel.nu/2012/03/… my own Initializer I'm using. I'll write.
The seed is definitely executed, so this method yields the same result, but it works even if you do not run installation, but run upgrade.
public partial class MyEntities : DbContext
{
static MyEntities()
{
Database.SetInitializer<MyEntities>(new ValidateDatabase<MyEntities>());
}
}
/// <summary>
/// http://coding.abel.nu/2012/03/prevent-ef-migrations-from-creating-or-changing-the-database/
/// </summary>
/// <typeparam name="TContext"></typeparam>
public class ValidateDatabase<TContext> : IDatabaseInitializer<TContext>
where TContext : DbContext
{
public void InitializeDatabase(TContext context)
{
if (!context.Database.Exists())
{
throw new ConfigurationErrorsException(
"Database does not exist");
}
else
{
if (!context.Database.CompatibleWithModel(true))
{
//from:
//http://stackoverflow.com/questions/11611322/ef-4-3-code-first-migrations-seed-per-migration
var cfg = new Migrations.Configuration();
var migrator = new DbMigrator(cfg);
///Last in the db, (first, the reverse order)
var dbLast = migrator.GetDatabaseMigrations().FirstOrDefault();
///last in the app
var appLast = migrator.GetLocalMigrations().LastOrDefault();
///what is missing
var pendings = string.Join(", ", migrator.GetPendingMigrations());
throw new InvalidOperationException(
string.Format("The database ({0}) is not compatible with the entity model ({1}). Pending migrations: {2}",
dbLast, appLast, pendings));
}
}
}
}
update: setup
Installation I'm using something like this:
http://coding.abel.nu/2012/04/update-database-msi-custom-action/
I finally fixed this by dropping the database manually then running the application with the original MigrateDatabaseToLatestVersion initializer. I had not realised that this would create the database if it did not exist and there was no need to use a DropCreateDatabaseAlways initializer then change to MigrateDatabaseToLatestVersion
I'm using Entity Framework code first in my website and I'm just wondering if there is any way to debug the migration codes. You know, like setting breakpoints and stuff like this.
I'm using Package Manager Console to update the database using Update-Database.
Thanks
I know that EF Code First Migrations is relatively new tool but don't forget about you are still in .NET.
So you can use:
if (System.Diagnostics.Debugger.IsAttached == false)
{
System.Diagnostics.Debugger.Launch();
}
After that you can see your InnerException.
Or you can use try...catch statement like this:
Exception handling Entity Framework
To hit a break point in a db migration set the context to MigrateDatabaseToLatestVersion on initialise.
Database.SetInitializer(new MigrateDatabaseToLatestVersion<EnterContextHere, Configuration>());
Then you just debug as normal (run using f5) and the breakpoint will hit the first time you run the project.
The problem now is that if you debug a second time the migration will not run. This is because the __MigrationHistory table has been updated to say you have migrated to the latest version. To re-test the migration open the package manager console and downgrade to the previous migration:
Update-Database –TargetMigration: ThePreviousMigrationName
My answer might be a bit silly but anyway here it goes.
If you, like me, some times have problems in the Seed() method what I usually do is simply create a public method that calls the Protect Seed().
public void SeedDebug(AppDbContext context)
{
Seed(context);
}
then in my HomeController I call this method in Debug mode.
public class HomeController : Controller
{
var appDb = new AppDbContext();
public ActionResult Index()
{
var config = new Configuration();
config.SeedDebug(appDb);
return View();
}
}
I know it's a bit lame solution, but it's simple and quick.
Of course this has to be done after the model been created.
So step by step:
comment the seed method and execute the update-database to create the model
uncomment the method Seed() and plugin the "hack" I mentioned above.
in the configuration disable Auto migrations
AutomaticMigrationsEnabled = false;//if you have this disabled already skip this step
Debug your application, fix the error and remove the "hack"
Here's a more fail-proof method which will do the trick without much fuss:
Step#1: Place this piece of code right above the migration you want to debug:
public partial class ORACLE_Test : DbMigration
{
public override void Up()
{
if (!System.Diagnostics.Debugger.IsAttached)
System.Diagnostics.Debugger.Launch();
AddColumn("TEST", "UR_USER_ID", x => x.Decimal(nullable: false, precision: 11, scale: 0, storeType: "number"));
AddColumn("TEST", "UR_CLIENT_ID", x => x.Decimal(nullable: false, precision: 11, scale: 0, storeType: "number"));
[...]
}
public override void Down()
{
}
}
Step#2: Compile the project containing your migrations
Step#3: Open a console inside the output directory (/bin/Debug, /bin/Release etc) containing the dll of your migrations
Step#4: Invoke migrate.exe with the /scriptFile parameter to launch the debugger and actually debug the desired db-migration
migrate.exe "Your.Migrations.Assembly.dll" /scriptFile="foo.sql" /verbose /startupConfigurationFile="Your.Migrations.Assembly.config"
Once the debugger-selector dialog pops up pick the visual studio instance that you have already opened.
You could add Console.WriteLine statements to the migration code (not a great solution)
Note, the messages are only shown if you run the migration code using the migrate.exe utility (in pacakges\EntityFramework.x.y.z\tools). They will not display if you run the migration through the Package Manager console.
I've had lots of luck using "Debugger.Launch()" (like in m_david's answer above) elsewhere, but inside of CreateDbContext it seems to somehow both attach, and not attach. What I mean is, it attaches and starts trying to step into .asm files and .cpp files (internal code). If I try to set a breakpoint on a Console.Writeline that I KNOW gets executed afterwards (I can see the output from ANY "dotnet ef migrations COMMAND") it both executes it and never hits the breakpoint.
This is what worked for me instead:
while (!System.Diagnostics.Debugger.IsAttached)
System.Threading.Thread.Sleep(10);
// Breakpoint after this...
You can execute the migration and manually attach using Visual Studio and it will actually let you step through the code like you expect, it's just more of a pain. What I should really try is the combination of both methods...
I also found a neat trick here to get the error details...
Basically, the trick is to grab all the information from an exception, put it in a string and throw a new DbEntityValidationException with the generated string and the original exception.
I am working with a database first model in Entity Framework 5 and when I attempt to add a row, I get the following error:
"No views were found in assemblies or could be generated for Table 'ui_renewals'."
The table exists in my EDMX and the template generated a ui_renewals class. I've deleted the table from the EDMX and added it again using the Update Model from Database option and I get the same error. Creating a separate connection for it resolves the issue, but that seems like a less-than-ideal solution (more like a kludge) not to mention it makes it more difficult to maintain in the future.
Any ideas on how to fix this so that I can add or update (I've tried both) a row in ui_renewals?
Here is the code I'm currently using - only difference before was using db as a DBContext instead of ui (yes, receipt is misspelled - gotta love legacy stuff)
[HttpPost]
public bool UpdateTeacher(string login_id, string password, UIRenewal data)
{
if (ModelState.IsValid)
{
// map from UIRenewal VM to ui_renewal
ui_renewals Renewal = Mapper.Map<UIRenewal, ui_renewals>(data);
// check to see if this is a new entry or not
var tmp = ui.ui_renewals.Find(Renewal.reciept);
if (tmp == null)
ui.ui_renewals.Add(Renewal);
else
{
// mark as modified
db.Entry(Renewal).State = EntityState.Modified;
}
// save it
try
{
ui.SaveChanges();
}
catch (DBConcurrencyException)
{
return false;
}
return true;
}
return false;
}
I should mention that I do have a view in the model (v_recent_license).
I know this is a very old question, however as I haven't found any other topics like this, I'll post my answer.
I have had the same Exception thrown. I found that, in a failed attempt to optimize EF performance, following the advices found here, I left behind this piece of code in EF .edmx code-behind:
<EntityContainerMapping StorageEntityContainer="XXXModelStoreContainer" CdmEntityContainer="YYYEntities" GenerateUpdateViews="false">
I removed the GenerateUpdateViews="false" string, and all is working again.
(The Exception message is a little misleading in my opinion).